Reaction of chickpea (Cicer arietinum) varieties to pulse beetle, (Callosobruchus maculates) (Fab.) THESIS Submitted to the Rajmata Vijayaraje Scindia Krishi Vishwa Vidyalaya, Gwalior in partial fulfilment of the requirements for the Degree of MASTER OF SCIENCE In AGRICULTURE (ENTOMOLOGY) By DESHRAJ PRAJAPATI Department of Entomology, Rajmata Vijayaraje Scindia Krishi Vishwa Vidyalaya College of Agriculture Gwalior (M.P.) 2015-16
CERTIFICATE I This is to certify that the thesis entitled Reaction of chickpea (Cicer arietinum) varieties to pulse beetle (Callosobruchus maculates) (Fab.) submitted in partial fulfilment of the requirement for the degree of MASTER OF SCIENCE in AGRICULTURE (Entomology) of Rajmata Vijayaraje Scindia Krishi Vishwa Vidyalaya, Gwalior is a record of the bona-fied research work carried out by Mr. Deshraj Prajapati under my guidance and supervision. The subject of the thesis has been approved by the Student s Advisory Committee and Director of Instruction. No part of the thesis has been submitted for any other degree or diploma or has been published. All the assistance and help received during the course of this investigations has been acknowledged by the scholar. Place : Gwalior Date : Committee (Dr. U.C. Singh) Chairman of the Advisory MEMBER OF STUDENT S ADVISORY COMMITTEE Chairman (Dr. U.C. Singh). Member (Dr. V.K. Shrivastava) Member (Dr. R. Lekhi) Member (Dr. V.B. Singh)
CERTIFICATE II This is to certify that thesis the entitled Reaction of chickpea (Cicer arietinum) varieties to pulse beetle (Callosobruchus maculates) (Fab.) submitted by Mr. Deshraj Prajapati to the Rajmata Vijayaraje Scindia Krishi Vishwa Vidyalaya, Gwalior in partial fulfilment of the requirements for the degree of MASTER OF SCIENCE in AGRICULTURE in the department of Entomology, College of Agriculture, Gwalior has been accepted after evaluation by the External Examiner and approved by the Student s Advisory Committee after an oral examination of the same. Place : Gwalior Date : (Dr. U.C. Singh) Chairman of the Advisory Committee MEMBERS OF THE ADVISORY COMMITTEE Chairman (Dr. U.C. Singh). Member (Dr. V.K. Shrivastava). Member (Dr. R. Lekhi). Member (Dr. V.B. Singh). Head of the Department (Signature) Dean of the collage (Signature) Director Instruction (Signature)..............
ACKNOWLEDGEMENT Words can never express indebtedness but I take this opportunity to express my deepest and heartfelt gratitude to reverend chairman of my Advisory Committee Dr. U.C. Singh, Professor, Department of Entomology, College of Agriculture, Gwalior for suggesting the problem and for his valuable guidance and scholarly advice during the course of investigation and for his healthy criticism in preparing the present manuscript of this thesis to make this task a success. I sincerely owe my deep gratitude to the members of my Advisory Committee Dr. V.K. Shrivastava, Professor & Head, Depratment of Entomology, Dr. R. Lekhi, Professor & Head, Department of Horticulture, and Dr. V.B. Singh, Professor & Head, Department of Mathematics and Statistics, College of Agriculture, Gwalior for their meticulous guidance and valuable suggestions during the course of study. I feel great pleasure to express my heartfelt thanks to Prof. A.K. Singh, Hon ble V.C., RVSKVV, Gwalior, Dr. B.S. Baghel, Director Instruction & SW, RVSKVV, Dr. (Smt.) Asha Arora, Dean, College of Agriculture, Gwalior, providing necessary facilities for conductive research ficilities. I am also greatful to Dr. N.S. Bhadauria, Professor and Deputy Registrar (Academic), RVSKVV, Gwalior and Dr. N.K.S. Bhadauria, Technical Assistant, Department of Entomology, College of Agriculture, Gwalior for their help during the course of this study. I am thankful to Sh. Rajendra Dhamdhere, Sh. Sunil Sisodia and Sh. Avanish Bhadauria, for their cooperation during the research work. I pay a lot of thanks to my friends Mr. Om Prakash Prajapati, Munesh Jatav, D. Chaurasia, Pawan, S. Nayak, Pradeep, Golu Uikey, Ms. Shainkey Jain, Pooja Prajapati, Vandana and Ms. Kavita Verma, who helped me whenever needed during my research work. At last, I don t have words to express my heartful gratitude towards my respected father Sh. Har Prasad Prajapati, mother Smt. Dhanmanti Devi, elder sister Smt. Phoola Prajapati and my Jiju Sh. Ratiram Prajapati, my brother Sh. Gulab Prajapati, Kamlesh Prajapati and Halkeram Prajapati, whose love, devotion and blessing have made my thesis possible. me. Finally, I express my sincere indebtedness to God who did all this through Date : Place : Gwalior (Deshraj Prajapati)
List of Contents Number Title Page 1 Introduction 1-4 2 Review of Literature 5-11 3 Material and Methods 12-14 4 Results 15-22 5 Discussion 23-25 6 Summary, Conclusion and Suggetions for Further Work 26-29 References 30-35 Vita
List of Tables Number Title Between Pages 3.1 The chickpea genotypes, their seed size and seed coat colour 4.1 Number of adults oriented on different genotypes of chickpea 4.2 Number of eggs laid on different genotypes under free choice condition 4.3 Number of eggs laid on different genotypes under forced condition 4.4 Number of adults emerged from different genotypes under forced condition 4.5 Total development period (in days) on different genotypes under forced condition 4.6 Survival percentage of pulse beetle on different genotypes of chickpea 4.7 Orientational and ovipositional preference, developmental period and survival percentage of pulse beetle, Callosobruchus maculatus (Fab.) on different categories of seed coat colour of chickpea genotypes 4.8 Orientational and ovipositional preference, developmental period and survival percentage of pulse beetle, Callosobruchus maculatus (Fab.) on different categories of seed size of chickpea genotypes 4.9 Per cent seed infestation and per cent loss in seed weight due to pulse beetle on different genotypes of chickpea 13 15 16 17 18 18 19 20-21 20-21 22
List of Figures Number Title Pages 1 Number of adults oriented on different genotypes of chickpea 2 Number of eggs laid on different genotypes under free choice condition 3 Number of eggs laid on different genotypes under forced condition 4 Number of adults emerged on different genotypes under forced condition 5 Survival percentage of pulse beetle on different genotypes of chickpea 6 Per cent seed infestation and per cent loss in seed weight due to pulse beetle in different genotypes of chickpea 15-16 16-17 17-18 18-19 19-20 22-21
Chapter I INTRODUCTION Pulses play an important role in human diet as they are considered to be main source of protein. The protein content of pulses range from 17 to 24 per cent. Protein being one of the most important constituent, supplying the building material for the body, thus the importance of pulses in our diet can be easily appreciated. Gram (Cicer arietinum Lin.) is the most important pulse accounting for more than one 3 rd of the area and about 40 per cent of the production of pulses in the country. Gram like other pulses is exclusively used for human and cattle feed, serving as a main source of protein in the diet cum nutrition. In human diet it is mostly used as dal (split pulse), besan (flour), crushed of whole grain, boiled pached, or cooked, salted or unsalted or sweet roasted preparations and green foliage and grain as vegetable are important forms in which it is consumed by people. It is also used for cattle feed as concentrate and roughage. Thus the value of gram to our agriculture is immense. Agricultural scientists are now paying much attention to this crop and improved insect and disease resistant varieties of excellent yield potential have been evolved and are available for sowing. Pulse beetle popularly known as Dhora is an important storage pest of chickpea in India. This includes three bruchid species, Callosobruchus maculatus (Fab.) (Salunkhe and Jadhav, 1982), C. chinensis Lin. (Reddy and Singh, 1972) and C. analis (Raina, 1971). Insect pests inflict their damage on stored products mainly by direct feeding. Some species feed on the endosperm causing loss of weight and quality, while other species feed on the germ, resulting in poor seed germination and less viability (Malek and Parveen, 1989; Santos et al., 1990). The seed-beetles in the genus Callosobruchus (Coleoptera: Bruchidae) are economically important pests of stored pulse crops (Weigand, 1990; Clement et al., 2004; Demanyk et al., 2007 and Sharma et al., 2007). The genus Callosobruchus includes approximately 20 species, about three quarters of which are from Asia (Borowiec 1987). These species are cosmopolitan pests of stored legumes (Fabaceae), including the genera Vigna, Phaseolus, Glycine, Lablab, Vicia, Pisum, Cicer, Lens, Cajanus and Arachis (Credland, 1987; Desroches et al. 1995; Yadav 1997; Ajayi and Laie 2000; Somta et al. 2006).
The pulse beetle, Callosobruchus maculatus F. (Coleoptera: Bruchidae), is an economically important pest of stored chickpeas, which produces losses up to 30% in a short period of two months (Yadav 1997). Its oviposition and growth are continuous. Females cement eggs to the surface of the host seeds. When eggs hatch, larvae burrow into the seeds where their entire development (four instars plus the pupal stage) is completed. Larvae cannot move among seeds and are thus restricted to the seed on which the female oviposited. Beetles emerge from seeds reproductively mature. Emerging adults are well adapted to storage conditions, requiring neither food nor water to reproduce (Messina 1991). Infestation with the seed beetle was reported to be up to 100% in many stored chickpea (Weigand and Pimpert 1993). When an infestation of 40 60% in chickpea occurs, the seeds are no longer edible (Van der Maesen, 1972). Because infestation by beetles most commonly occurs in stored seed, laboratory conditions do not significantly differ from their natural conditions (Southgate, 1979). The general biology of the insect indicates that, on an average each female lays 50 to 70 eggs during her life span. Eggs are generally laid singly on the grain and more than one egg is also laid on each grain. Eggs are small and oval in shape and are white in colour. The eggs hatch in about a week s time and new young larva laid on the grains or crevices. Larval and pupal stages are completed inside the grain and start adults emerging out of the grains after a fortnight. The adult emerges out through a fairly large emergence hole. The results of Shafique and Ahmad (2005) revealed that preference of the bruchid for host selection/ oviposition appeared to be sensory to a larger extent as low number of eggs were laid on wrinkled and black grains genotypes. Grains of chickpea genotypes with wrinkled seed coat and black colour affected the beetle development and seemed to be less preferred than the smooth, plumpy and white colour seeds of chickpea cultivars. A prominent white ring as a demarcation of emergence hole can be seen on the grain before the adult emergence. The adult emergence continues up to 28 days. Usually females live longer than males. Total life cycle is completed in about 4 to 5 weeks (Radha and Susheela, 2014). Most of the pulse beetle infests the pods and grains from the field and hidden infestation is not detected before storing of the pulses. So, the heavy amount of stored produce is lost by the beetles. Therefore, it is essential to know the factors
responsible for causing this damage (Arora and Singh 1970 and Shehnaz and Theophillus 1975). Mukherjee et al. (1970) reported that leguminous seeds were more damaged by this pulse beetle (32.64 %) as compared with those of vegetable and oil seeds (3 %). The losses in seed by insect infestation due to improper storage in India has been reported to be lower in chickpea (4.8%) in comparison to pigeonpea (32.68%), cowpea (18.5%), urd (14.9%). Pulse beetle C. chinensis is one of the serious storage pests of Chickpea. C. chinensis has been reported to cause serious damage to pulses in India and many countries of the globe. It is cosmopolitan in distribution found in the countries where tropical and subtropical conditions prevail. It has a capability to infest not only cultivated host plants in the field but also in storage (Fahad, 2011). It is recorded that 55-60% loss in seed weight and 45.50 to 66.30% loss in protein content of pulses is due to infestation caused by this beetle (Faruk et al., 2011). In case of heavy infestation of grains by pulse beetle the grains lose their germination capacity and become unfit for human consumption. To reduce storage losses in pulses, usually some chemicals or fumigants are applied. The use of these chemicals not only increase input cost but also is health hazardous. Therefore, there is a need to search for some non-chemical methods. Investigating resistance source in the cultivable varieties is the best option in this regard. The present study is therefore planned to chickpea varieties having variation in seed size and seed colour was screened. Keeping these points in view, the present study was conducted to screen chickpea varieties against pulse beetle with the following objectives:- 1. To screen out less preferred variety of chickpea against pulse beetle on the basis of orientation and oviposition. 2. To study the reaction of chickpea varieties on development and survival of pulse beetle. 3. To study the relation of seed size and seed coat colour on orientational and ovipositional preference, development and survival of pulse beetle. 4. To work out the losses caused by pulse beetle in different varieties of chickpea.
Chapter II REVIEW OF LITERATURE The literature according to the objectives of present study is reviewed and presented in the chapter. Wadnerkar et al. (1978) investigated susceptibility of three gram cv. (N-59, Chaffa and White gram) and four Arhar cv. (PT-307, Prabhat, No. 148 and T-21) to infestation by Callosobruchus maculates by allowing adult insects into plastics containers with the grains for five days to lay eggs. For oviposition, arhar was preferred. Insects showed very rapid development on White gram. The percent loss in weight ranged from 25.07 to 44.73 in arhar and from 9.67 to 13.59 in gram. Akhtari et al. (1993) observed that the Callosobruchus chinensis had less preference for oviposition on seeds of small sized bean (Lablab purpureus) genotypes with increased egg deposition on medium to large seeded beans. The damage caused by this insect to small seeded genotypes was below 10%, and to medium and large seeded beans was 23-31%. Infested bean seeds without holes but with eggs germinated almost as well as those of healthy seeds and produced normal seedlings. Of three insecticides applied to seeds with freshly laid eggs, diazinon reduced adult emergence substantially at all doses. Malathion and Sevin [carbaryl] were ineffective as ovicidal agents. Khattak et al. (1991) carried out laboratory experiments with six chickpea varieties, at 28±2 0 C and 60.5% relative humidity and reported cv. CM-72 was the most resistant to infestation by C. chinensis. Wijenayake and Karunaratne (1999) made a comparative study of the ovipositional preference and developmental response of the cowpea beetle, C. chinensis in the laboratory using six, commonly available pulses. The beetle preferred smooth coated seeds for oviposition and rejected seeds with a rough coat. The most preferred seeds for oviposition were moong and soybean whereas chickpea was least preferred. The study revealed that the ovipositional preference was not an indication of suitability for the larval development. Development was comparatively faster in mung and the black and white varieties of cowpea followed by chickpea. A hundred percent larval mortality was found in soybean. On the basis
of ovipositional preference, growth index and fecundity, mung bean and the white and the black varieties of cowpea proved to be most suitable for the development of the cowpea beetle. Based on the performance of the beetles, green pea was found to be most resistant to attack by the cowpea beetle. Khattak et al. (2001) screened 10 chickpea cultivars (CMN-122, CMN-7, CMN-729-2, CMN-730-2, NIFA-95, CMNK-220-4, CMNK-287-3, CMNK-421-9, CMNK-425-10 and Noor-91) for resistance against pulse beetle C. maculatus under controlled laboratory conditions. Ten pairs of one-day-old adults were released in 10 x 5 cm glass jars containing 75 g samples of test cultivars. The experiment was continued until the first generation completed. Evaluation based on the oviposition preference, development, longevity of the beetle and weight loss of grains revealed that CMN-122 was comparatively resistant, while NIFA-95 was highly susceptible. The proximate analysis of the cultivars did not show a consistent effect on resistance to the pest. Shafique and Ahmad (2002) screened grains of pulse cultivars/elite lines (9 of lentil, 15 of mungbean, 7 of chickpea, 2 of black gram and one of cowpea) for resistance to pulse beetle (Callosobruchus analis) under laboratory conditions (28±2 0 C and 65±5% RH). The results revealed that oviposition, adult progeny development and grain weight loss varied significantly among cultivars/promising lines of various pulses. Lentil cultivars 791-1 and Precoz, mungbean genotypes ML 613, NMB 101, KPS 1, CO3 and 6153B-20G, and chickpea cultivars CM 72 and Paidar 91 harboured significantly lower number of eggs, inhibited adult progeny development and decreased grain weight loss, indicating resistance to C. analis. No adult progeny developed in black gram cultivars (M 88 and M 97) despite egg deposition by the female beetles. Shafique and Ahmad (2005) screened grains of 22 chickpea genotypes for resistance to pulse beetle (Callosobruchus analis) under laboratory conditions (28±2 0 C and 60±5% RH). The results revealed that free choice oviposition by the beetle, adult progeny development, grain damage and weight loss varied significantly (P<=0.05) among chickpea cultivars. The genotypes CM 3142-2/92, CM 88, CM 3142-3/92, CM 72, and Pb 91 harboured significantly lower number of eggs, adult progeny development, damage and grain weight loss indicating resistance to C. analis. The preference of the bruchid for host selection/oviposition seemed to be
sensory to a larger extent, as low number of eggs were laid on wrinkled and black grains genotypes. Shaheen et al. (2006) conducted a study to evaluate the resistance of 15 chickpea cultivars viz., Paidar-91, C-44, Noor-91, Bittle-98, Parbat, Punjab-91, NCS- 2003, CM-2000, CH-41/91, Flip 97-192C, Dasht, C-44 E-100YM, NUYT-90395, BH- 73111 and CM-72 against pulse beetle. The cultivars with rough, wrinkled, hard and thick seed coat were more resistant compared to those having smooth, soft and thin seed coat. The minimum number of holes (0.80 per grain) made by pulse beetle was recorded in grains of Punjab-91 compared to the maximum of 1.77 holes per grain in Paidar-91. The maximum number of eggs (3.12 per grain) of pulse beetle was observed in Paidar- 91 and the minimum eggs (0.48 per grain) were recorded in Dasht. The adults of pulse beetle fed on Paidar-91 gained the maximum weight (10.27 mg) while the minimum weight of 7.02 mg was recorded for adults fed on grains of Bittle-98. The minimum grain damage (24.35%) was recorded in Bittle-98 while the maximum of 54.46% damage was seen in Flip 97-192C. The minimum grain weight loss of 25.66% was recorded for Dasht compared to the maximum weight loss (39.48%) in CM-2000. The minimum adults (2.96) of pulse beetle were attracted towards Parbat grains and the maximum of 5.07 adults were recorded in grains of Flip 97-192C. Chickpea cultivars of Punjab-91, Dasht, Bittle-98 and Parbat were resistant against pulse beetle while Paidar-91 and Flip 97-192C were found susceptible. Parameshwarappa et al. (2007) studied 12 varieties of Chickpea viz., A-1, ICCV-2, ICCV-10, ICCV-0311, ICCV-03308, ICCV-03311, ICCV-03307, ICCV- 03303, ICCV-10303, ICCV-03109, ICCV-03203 and ICCV-103205 for extent of damage, seed quality, varietal resistance and susceptibility to pulse beetle (Callasobruchus chinensis L.). None of the twelve varieties of chickpea was found immune to the infestation by Callasobruchus chinensis L. However, there was significant difference in relative susceptibility of different varieties to bruchid attack. It was found that ICCV-10 was the most susceptible whereas ICCV-03311 was the least susceptible variety as compared to other varieties. The variety ICCV-03311 was also least in loss of germination per cent and seedling vigour index at 60 days after release of bruchids in storage as compared to other varieties.
C. chinensis adults were maintained in glass tubes containing malathion 50 EC (1.0 ml/litre), or water, ethanol, methanol and acetone leaf extracts of ipomoea (Ipomoea carnea), marigold (Tagetes sp.), nisinda (Vitex negundo), neem (Azadirachta indica) or pudina (Mentha sp.) for 1, 3 or 6 h. Insect mortality was evaluated after 6, 12, 24 and 48 h, and until the death of the beetles following their transfer into another container. Malathion 50 EC resulted in the highest mortality percentage (100%). Among the various extracts, the ipomoea extracts resulted in the highest mortality levels after 1, 3 and 6 h of exposure. However, the efficacy of ipomoea significantly varies with the solvent used. The highest mortality level was obtained with the methanol extract of ipomoea, followed by the acetone, ethanol and water extracts. Nisinda was effective only when mixed with water for exposure periods of 1, 3 and 6 h. Pudina was effective only after 6 h of exposure to all extracts except the water extract. The results suggested that instead of malathion, ipomoea or neem with methanol or acetone can be used as chickpea grain protectants against pulse beetle (Manual et al., 2008). Navreet and Gill (2008) studied growth and development of pulse beetle, C. chinensis on 10 kabuli and 13 desi chickpea genotypes during July-August 2005. They reported that larval penetration, development of larvae up to the last larval instar/pupal stage, adult emergence and growth index did not vary significantly among the different chickpea genotypes. Genotypes GLK 21159, GL 21107, GL 22038, PBG 1 and GLK 23023 recorded significantly longer development period (27.00, 26.67, 26.67, 26.67, 26.33 days, respectively) and less seed damage (49.99, 52.22, 54.44, 52.22, 55.55%, respectively), whereas PBG 204 recorded shorter development period (25.67 days) and higher grain damage (71.11%). Differences in the adult longevity among different chickpea genotypes were significant only in females. The correlations of hardness of seeds with adult emergence (r=-0.310), grain damage (r=-0.183) and weight loss (r=-0.015) and of seed coat thickness with larval penetration (r=-0.273) and adult emergence (r=-0.004) were non-significant. Erler et al. (2009) reported chickpea (Cicer arietinum L.), seeds were vulnerable, both in the field and in storage, to attack by seed-beetles. Beetles of the genus Callosobruchus were major storage pests of chickpea crops and caused considerable economic losses. A total of 11 chickpea genotypes including five 'kabuli' (Mexican white, Diyar, CA 2969, ILC 8617 and ACC 245) and six 'desi'
chickpeas (ICC 1069, ICC 12422, ICC 14336, ICC 4957, ICC 4969 and ICC 7509) were evaluated for resistance to the pulse beetle Callosobruchus maculatus F. (Coleoptera: Bruchidae). Resistance was evaluated by measuring per cent damage to seeds. Damage to seeds by C. maculatus was manifested by the round exit holes with the 'flap' of seed coat made by emerging adults. Of the 11 genotypes tested, only one (ICC 4969) exhibited a complete resistance to C. maculatus in both freechoice and no-choice tests; no seed damage was found over the test period. In general, the 'desi' chickpeas were more resistant to C. maculatus than the 'kabuli' chickpeas. Among the tested chickpea genotypes, only ICC 4969 can be used as a source of C. maculatus resistance in breeding programmes. Pokharkar and Chauhan (2010) screened 11 chickpea (Cicer arietinum) genotypes against pulse beetle, C. chinensis (L.). Differences in their susceptibility were recorded on the basis of percentage grain damage, per cent weight loss and per cent germination. Maximum chickpea seed damage (81.60%) and weight loss (75.67%) were found in variety Kabuli and germination (33.83%) was found in variety Vishal, while minimum seed damage (62.79%) and weight loss (35.63%) were found in variety Vishal and less germination (11.83%) was found in variety Kabuli. Muhammad (2012) noted chickpea (Cicer arietinum L.), commodity severely attacked by bean beetle Callosobruchus maculatus (Fabricius), resulting losses in quantity and nutritional quality. Further he studied relative resistance of 12 chickpea genotypes to the attack of C. maculatus during storage. The genotypes most tolerant to bruchids comprised CH-52/02 and B-8/03, whereas, the most susceptible were CH-86/02 and CC-117/00. The moderate pest incidence was observed in CH-28/02, CH-4/02, CH-32/02, CH-31/02, CH-9/02, CM-772/03, B-8/02 and CM-628/03 genotypes. The tolerant genotypes exhibited hard and wrinkled seed coat, dark brown colour and small size grain. These characteristics demonstrated a significant harmful effect to pest appearance and grain damage. The vulnerable genotypes had soft and smooth seed coat, white seed colour and bigger grain size that caused vulnerability to C. maculatus. Based on the investigation, chickpea genotypes CH- 52/02 and B-8/03 deserve special consideration and may be recommended for relatively longer storage to achieve the goal of long term and sustainable pest management strategies.
Tripathi et al. (2012) evaluated fifty two cowpea genotypes including two checks Pusa Komal and Local variety for their differential reaction to pulse beetle, Callosobruchus maculatusunder no-choice artificial infestation conditions. Significant differences were observed among the genotypes in terms of number of eggs laid, development period, adult emergence, number of emergence holes, weight loss and growth index of C. maculatus on cowpea. Based on growth indices of C. maculatus on cowpea, three genotypes (IC107466, IC106815 and Pusa Komal) were found resistant, nine as moderately resistant, 18 as moderately susceptible, 18 as susceptible and 4 were highly susceptible. Correlation between growth index and growth parameters of beetle on cowpea genotypes indicated that growth index had significant negative relationship with mean development period (r = -0.90) and significantly positive relation with adult emergence (r = 0.83). Adult emergence had a positive relationship with weight loss (r = 0.43) and number of eggs laid by C. maculatus had a significant negative relationship with adult emergence (r = -0.36). Siddiqa et al. (2013) conducted experiments on the response of pulse beetle, Callosobruchus chinensis on five chickpea, (Cicer arietinum L.) varieties KK-1, KK-2, KC-98, Lawaghar and Sheenghar under laboratory condition. Two sets of experiment; no-choice test and free choice test were carried out in the Complete Randomized Design (CRD) with four replications. The results were evaluated on the basis of eggs laid/female, developmental period, total number of adults emerged, adult longevity of male and female, adult weight (mg), per cent adult emergence, per cent grain damage and weight loss. Results of no-choice test revealed that none of the cultivar was completely resistant to C. chinensis, however, their response varied significantly. Taking weight loss as a standard parameter, cultivar Lawaghar (4% weight loss) was significantly least susceptible, KK-2 (28%) and Sheenghar (31%) moderately susceptible while KC-98 (60%) and KK-1 (70%) were highly susceptible. The results of free choice test also revealed that none of the cultivars was completely immune to the attack of C. chinensis. In free-choice test, variety Lawaghar also received significantly less number of eggs by C. Chinensis. Siddiqa et al. (2015) recorded morphological data 1 st before starting laboratory work. In free choice test, the response of both species of Callosobruchus on candidate variety for oviposition was different. The adult emergence of both species of Callosobruchus on candidate varieties showed no significant difference. Both species of Callosobruchus in free choice test have no significant difference for
percent adult s emergence on candidate varieties. Percent damage of both species of Callosobruchus on candidate varieties was different. A total of 52 accessions of cowpea including two checks (Pusa Komal and Local variety) were screened for resistance to pulse beetle, Callosobruchus chinensis under no-choice artificial infestation conditions. There were significant differences among the accessions in terms of number of eggs laid, development period, adult emergence, number of emergence holes, weight loss and growth index of C. chinensis on cowpea. Based on growth indices, Pusa Komal (0.04081) and IC328859 (0.04112) were resistant while IC106033 (0.06819) and Local variety (0.06816) were most susceptible to C. chinensis of the 52 accessions screened, 11 accessions were resistant, 15 moderately resistant, 13 moderately susceptible, eight susceptible and five were highly susceptible to C. chinensis. Correlation between growth index and growth parameters of pulse beetle on different cowpea accessions indicated that growth index had significant negative relationship with mean development period (r = -0.68) and significant positive relationship with adult emergence(r = +0.80). Adult emergence had a positive relationship with weight loss (r = +0.22) (Tripathi et al., 2015).
Chapter III MATERIAL AND METHODS A research experiment entitled, Reaction of chickpea (Cicer arietinum) varieties to pulse beetle (Callosobruchus maculatus) (Fab.) was carried out in the Laboratory of Department of Entomology, College of Agriculture, Gwalior. The material used and methods followed in this investigation are as given below: Pulse beetle (Callosobruchus maculatus) (Fab.) was reared in the laboratory to raise experimental culture of the insect. For rearing the insect in large numbers, about 500 g seed of local variety of chickpea was taken in glass jar and 100 pair of newly emerged adults were released in Jar. Jar was covered with muslin cloth and kept in incubators at 29 0 ±1 0 C temperature. After egg laying dead adults were removed by skiving. Fresh adults started emerging after 22 to 28 days. The newly emerged adults were used for experiment. Studies were conducted with 12 varieties of chickpea having variation in seed size and seed coat colour. The genotypes were categorized as under (Table 3.1): 1. Seed size (on the basis of weight of 100 seeds) (i) (ii) Small (less than 18 g / 100 seeds) Medium (18 to 22 g / 100 seeds) (iii) Bold (more than 22 g / 100 seeds) 2. Seed coat colour (on the basis of visual observations) (i) (ii) (iii) Light yellow Brown Dark brown
Table 3.1: The chickpea varieties, their seed size and seed coat colour S.No. Genotypes Weight of 100 seeds (g) Seed size category Seed coat colour category 1. RVS-201 24.20 Bold Light yellow 2. RVS-202 23.04 Bold Light yellow 3. RVS-203 17.95 Small Brown 4. JG-6 20.22 Medium Light yellow 5. JG-11 22.02 Medium Brown 6. JG-16 14.33 Small Brown 7. JG-130 13.61 Small Brown 8. JG-322 14.07 Small Brown 9. JGK-1 16.01 Small Brown 10. JKG-3 16.47 Small Dark brown 11. JGK-43 26.02 Bold Dark Brown 12. JGG-1 17.81 Small Brown Details of the experiment : (A) Design : CRD (B) Replication : 3 (C) Number of varieties : 12 1. RVS-201 2. RVS-202 3. RVS-203 4. JG-6 5. JG-11 6. JG-16 7. JG-130 8. JG-322 9. JGK-1 10. JKG-3 11. JGK-43 12. JGG-1 Two experiments were conducted during the present investigations. The details of which are as under:
Experiment 1: Orientation and ovipositional preference were assessed under free choice conditions. Fifty seeds of each variety were kept in open Petridishes and arranged randomly in glass trough. Fifty pairs of freshly emerged beetles were released in the centre of the trough and the glass trough was then covered with muslin cloth. The adults oriented in every variety were counted at 72 hours after their release and then were removed. The experiment was replicated three times. Seven days after removing the adult, the eggs laid in each genotype were counted to note the ovipositional preference. Experiment No. 2 : Fifty seeds of each variety were kept in Petridishes replicated three times. Five pairs of pulse beetle were released in each Petridish for 72 hours and then removed. Number of eggs laid on the grains of every variety were counted at seven days after the release. Petridishes were observed daily to record the beetle emerged. The developmental period, survival and extent of grain damage were worked out. Weight of healthy and damaged seed was also recorded to work out the per cent loss in grain weight. The effect of seed size and seed coat colour was also studied. The data were subjected to n or angular (arc sin) transformation as the case may be for statistical analysis. The data obtained were statistically analysed by using the analysis of variance as described by Fisher (1958).
Chapter- IV RESULTS During the present investigation, the response of chickpea varieties on orientation, ovipositional preference, development and survival of pulse beetle, Callosobruchus maculatus (Fab.) were studied, under laboratory conditions in the Department of Entomology, College of Agriculture, Gwalior during 2013-14. Twelve varieties of chickpea having variation in seed size and seed coat colour were included in the study. The obtained results are presented here with: A. RESPONSE UNDER FREE CHOICE CONDITION Orientational preference Data recorded on number of adults oriented on different varieties showed significant differences among different varieties (Table 4.1 and Fig 1). Minimum number of adults (6.0) was oriented on JG-16 which was found significantly less than the adults oriented on varieties JGK-43, JG-11, RVS-201, JKG-3, JG-130 and JG- 322, but was at par with rest of the varieties. Table 4.1: Number of adults oriented on different varieties of chickpea S. No. Varieties Number of adults oriented 1 RVS-201 7.0 (2.64) 2 RVS-202 9.0 (3.00) 3 RVS-203 10.0 (3.16) 4 JG-6 10.3 (3.21) 5 JG-11 6.7 (2.57) 6 JG-16 6.0 (2.43) 7 JG-130 8.0 (2.83) 8 JG-322 8.3 (2.87) 9 JGK-1 9.3 (3.05) 10 JKG-3 7.0 (2.64) 11 JGK-43 6.3 (2.51) 12 JGG-1 9.3 (3.05) SE(m)± (0.15) CD at 5% (0.45) * Figures in parentheses are n transformed values
Number of adults oriented 10 9 8 7 6 7.0 9.0 Fig 1: Number of adults oriented on different varieties of chickpea 10.0 10.0 9.3 8.3 8.0 7.0 6.3 6.0 6.0 9.3 5 4 3 2 1 0 RVS-201 RVS-202 RVS-203 JG-6 JG-11 JG-16 JG-130 JG-322 JGK-1 JKG-3 JGK-43 JGG-1 Varieties
The maximum adult orientation (10.3) was observed in varieties JG-6, which was found significantly higher than the adults oriented on varieties RVS-203, JGK1, JGG- 1, RVS-202, JG-322 and JG-130, but was at par with rest of the varieties. Ovipositional preference There existed significant differences in the egg deposition on different varieties (Table 4.2 and Fig 2). Significantly lower number of eggs (13.0) was laid on genotypes JG-11 and JG-16 than rest of the varieties, except JGK-43, RVS-201, JKG-3, JG-130 and JG-322. Whereas, maximum number of eggs (21.0) were laid in varieties RVS-203 and JG-6, which was found significantly higher than the number of eggs laid on varieties JGG-1, JGK-1, RVS-202, JG-322 and JG-130, but was at par with rest of the varieties. Table 4.2: Number of eggs laid on different varieties under free choice condition S. No. Varieties Number of eggs laid 1 RVS-201 15.0 (3.87) 2 RVS-202 18.3 (4.28) 3 RVS-203 21.0 (4.57) 4 JG-6 21.0 (4.57) 5 JG-11 13.0 (3.60) 6 JG-16 13.0 (3.60) 7 JG-130 16.7 (4.08) 8 JG-322 17.0 (4.11) 9 JGK-1 20.0 (4.45) 10 JKG-3 15.0 (3.87) 11 JGK-43 13.7 (3.68) 12 JGG-1 20.0 (4.47) SE(m)± (0.19) CD at 5% (0.56) * Figures in parentheses are n transformed values B. RESPONSE UNDER FORCED CONDITION Ovipositional preference Data recorded on number of eggs laid on different genotypes showed significant differences among different varieties (Table 4.3 and Fig 3). Minimum
Number of eggs laid Fig 2: Number of eggs laid on different varieties under free choice condition 25 20 15 15.0 18.3 21.0 21.0 13.0 13.0 16.7 17.0 20.0 15.0 13.7 20.0 10 5 0 RVS- 201 RVS- 202 RVS- 203 JG-6 JG-11 JG-16 JG-130 JG-322 JGK-1 JKG-3 JGK-43 JGG-1 Varieties
number of eggs (45.0) was laid on varieties RVS-201, which was found significantly less than the eggs laid on varieties JGK-43, JKG-3, RVS-203 and JG-322. On the other hand, maximum number of eggs (115.3) was laid on varieties JG-16, which was found significantly higher than the eggs laid on rest of the varieties, except JGK- 1 and JGG-1. Table 4.3: Number of eggs laid on different varieties under forced condition S. No. Varieties Number of eggs laid 1 RVS-201 45.0 (6.68) 2 RVS-202 84.0 (9.12) 3 RVS-203 77.3 (8.79) 4 JG-6 91.7 (9.57) 5 JG-11 82.7 (9.05) 6 JG-16 115.3 (10.72) 7 JG-130 83.0 (9.11) 8 JG-322 77.3 (8.79) 9 JGK-1 103.0 (10.15) 10 JKG-3 76.7 (8.75) 11 JGK-43 64.7 (8.03) 12 JGG-1 98.0 (9.90) SE(m)± (0.36) CD at 5% (1.05) * Figures in parentheses are n transformed values Number of adults emerged under forced condition Significant difference was observed among different varieties with regards to number of adult emerged from different varieties of chickpea under forced condition (Table 4.4 and Fig 4). Minimum number of adults (22.0) was emerged from RVS- 201, which was found significantly less than the adult emerged from varieties JG-6, but was at par with rest of the varieties. Whereas, maximum number of adult (43.7) was emerged in varieties RVS-202, which was found significantly higher than the number of adult emerged from rest of the varieties, except JGG-1, JG-16, JGK-1, JG-11, RVS-203 and JG-130.
Number of eggs laid 120 100 80 84.0 Fig 3: Number of eggs laid on different varieties under forced condition 77.3 91.7 82.7 115.3 83.0 77.3 103.0 76.7 64.7 98.0 60 45.0 40 20 0 RVS- 201 RVS- 202 RVS- 203 JG-6 JG-11 JG-16 JG-130 JG-322 JGK-1 JKG-3 JGK-43 JGG-1 Varieties
Table 4.4: Number of adults emerged on different varieties under forced condition S. No. Varieties Number of adult emerged 1 RVS-201 22.0 (4.67) 2 RVS-202 43.7 (6.60) 3 RVS-203 36.3 (6.01) 4 JG-6 23.7 (4.85) 5 JG-11 37.3 (6.07) 6 JG-16 41.3 (6.40) 7 JG-130 34.7 (5.88) 8 JG-322 32.3 (5.68) 9 JGK-1 40.0 (6.32) 10 JKG-3 30.7 (5.53) 11 JGK-43 30.7 (5.53) 12 JGG-1 43.3 (6.58) SE(m)± (0.28) CD at 5% (0.82) * Figures in parentheses are n transformed values Development period of pulse beetle Table 4.5: Total development period (in days) on different varieties under forced condition S.No. Varieties Total developmental period (in days) 1 RVS-201 30.0 2 RVS-202 31.1 3 RVS-203 29.0 4 JG-6 28.2 5 JG-11 32.0 6 JG-16 30.3 7 JG-130 29.4 8 JG-322 30.3 9 JGK-1 31.6 10 JKG-3 29.5 11 JGK-43 28.0 12 JGG-1 30.9 SE(m)± 2.07 CD at 5% NS
Number of adult emerged 45 40 35 30 25 22.0 Fig 4: Number of adult emerged on different varieties under forced condition 43.7 43.3 41.3 40.0 36.3 37.3 34.7 32.3 30.7 30.7 23.7 20 15 10 5 0 RVS- 201 RVS- 202 RVS- 203 JG-6 JG-11 JG-16 JG-130 JG-322 JGK-1 JKG-3 JGK-43 JGG-1 Varieties
Data recorded on developmental period (egg to adult) of pulse beetle on different varieties of chickpea showed that there was no significant differences among different varieties. However, the total developmental period ranged from 28.0 days in JGK-43 to 32.0 days in JG-11. Survival percentage Significant differences was observed among different varieties with regards to survival percentage of pulse beetle (Table 4.6 and Fig 5). The survival percentage in variety JG-6 was significantly low (26.33%) than rest of the varieties, except JGK- 43. Whereas, significantly high survival percentage (44.64%) was recorded in varieties JGG-1 than rest of the varieties, except RVS-203, JG-130, JG-322, JKG-3 and JGK-1. Table 4.6: Survival percentage of pulse beetle on different varieties of chickpea S. No. Varieties Survival percentage 1 RVS-201 34.08 (35.73) 2 RVS-202 35.31 (36.12) 3 RVS-203 44.29 (41.71) 4 JG-6 26.33 (30.75) 5 JG-11 37.05 (37.50) 6 JG-16 35.98 (36.85) 7 JG-130 41.99 (40.39) 8 JG-322 41.95 (40.38) 9 JGK-1 39.20 (38.76) 10 JKG-3 40.14 (39.31) 11 JGK-43 29.15 (32.68) 12 JGG-1 44.64 (41.92) SE(m)± (1.21) CD at 5% (3.55) * Figures in parentheses are angular transformed values
Survival percentage of pulse beetle Fig 5: Survival percentage of pulse beetle on different varieties of chickpea 45 40 35 34.1 35.3 44.3 37.0 36.0 42.0 42.0 39.2 40.1 44.6 30 26.3 29.2 25 20 15 10 5 0 RVS- 201 RVS- 202 RVS- 203 JG-6 JG-11 JG-16 JG-130 JG-322 JGK-1 JKG-3 JGK-43 JGG-1 Varieties
RELATIONSHIP OF SEED COAT COLOUR WITH ORIENTATION OF BEETLES Data recorded on orientation of beetle revealed that seed coat colour influenced the orientation of pulse beetle significantly (Table 4.7). The orientation of beetle on the varieties of different seed coated colour ranged from 6. 7 (dark brown) to 8.7 (light yellow). The orientation of adults on dark brown seeded varieties was significantly less than light yellow and brown seeded varieties. There were no significant difference in orientation of pulse beetle on light yellow seeded and brown seeded varieties of chickpea. RELATIONSHIP OF SEED COAT COLOUR WITH OVIPOSITION Data recorded on number of eggs laid by pulse beetle on chickpea varieties of different seed coat colour showed significant difference among them. Minimum number of eggs was laid on the varieties of dark brown in colour (14.3), which was found significantly less than the eggs laid on the seeds of rest of the colours. The egg deposition on brown seeded varieties was at par with egg deposition on light yellow seeded varieties. RELATIONSHIP OF SEED COAT COLOUR WITH TOTAL DEVELOPMENTAL PERIOD Data recorded on total developmental period on different varieties of different seed coat colour showed that seed coat colour did not influence the developmental period of pulse beetle. However, the developmental period on different seed coat colour was ranged from 28.7 to 30.5 in the dark brown and brown seed coat colour varieties, respectively. RELATIONSHIP OF SEED COAT COLOUR WITH SURVIVAL PERCENTAGE Observations recorded on survival percentage of pulse beetle on the varieties of different seed coat colour indicated that, there were no significant relationship of seed coat colour and survival of the beetle. However, the survival percentage was ranged from 31.9 (light yellow seed coat) to 40.7 (brown seed coat).
Table 4.7: Orientational and ovipositional preference, developmental period and survival percentage of pulse beetle, Callosobruchus maculatus (Fab.) on different categories of seed coat colour of chickpea genotypes. S. No. Seed coat colour category and genotypes Number of adults oriented* Number of eggs laid * Total developmental period (in days) Survival ** percentage A. Mean Light Yellow 8.67 (2.93) 18.11 (4.24) 29.74 31.91 (34.20) B. Mean Brown 8.14 (2.83) 17.24 (4.13) 30.50 40.73 (39.64) C. Mean Dark Brown 6.67 (2.57) 14.33 (3.77) 28.73 34.65 (36.00) SE(m)± and CD at 5% for between the SE(m)± CD SE(m)± CD SE(m)± CD SE(m)± CD seed coat colour A - B (0.10) (NS) (0.13) (NS) 1.42 NS (0.83) (NS) A - C (0.13) (0.27) (0.18) (0.36) 1.88 NS (1.10) (NS) B - C (0.12) (0.24) (0.16) (0.32) 1.65 NS (0.97) (NS) SE(m)± and CD at 5% for within the seed coat colour of the genotypes (0.20) (0.42) (0.27) (0.56) 2.92 6.02 (1.71) (3.53) * Figures in parentheses are n * and angular** transformed values Table 4.8: Orientational and ovipositional preference, developmental period and survival percentage of pulse beetle, Callosobruchus maculatus (Fab.) on different categories of seed size of chickpea genotypes. S.No. Seed size category and genotypes Number of adults oriented* Number of eggs laid * Total developmental period (in days) Survival ** percentage A. Mean Small 7.44 (2.71) 15.67 (3.94) 29.68 32.85 (34.84) B. Mean Medium 8.29 (2.86) 17.52 (4.16) 30.14 41.17 (39.90) C. Mean Bold 8.00 (2.80) 17.00 (4.08) 30.09 31.69 (34.12) SE(m)± and CD at 5% for between the SE(m)± CD SE(m)± CD SE(m)± CD SE(m)± CD seed size A - B (0.10) (NS) (0.13) (NS) 1.42 NS (0.83) (NS) A - C (0.13) (NS) (0.18) (NS) 1.88 NS (1.10) (NS) B - C (0.12) (NS) (0.16) (NS) 1.65 NS (0.97) (NS) SE(m)± and CD at 5% for within the seed size of the genotypes * Figures in parentheses are n * and angular** transformed values (0.20) (0.42) (0.27) (0.56) 2.92 6.02 (1.71) (3.53)
RELATIONSHIP OF SEED SIZE WITH ORIENTATION OF BEETLES Data recorded on number of adults oriented on different varieties of different seed size showed that seed size did not influence the orientation of pulse beetle. However, the number of adults oriented on different seed size was ranged from 7.4 to 8.3 in the small and medium seeded varieties, respectively. RELATIONSHIP OF SEED SIZE WITH OVIPOSITION Observations recorded on eggs deposited on chickpea varieties of different seed size indicated no significant relationship of seed size with egg deposition. However, it ranged from 15.7 to 17.5 small and medium seeded varieties, respectively. RELATIONSHIP OF SEED SIZE WITH TOTAL DEVELOPMENT PERIOD Data recorded on total developmental period on different varieties of different seed size showed that seed size did not influence the developmental period of pulse beetle. However, the developmental period on different seed size was ranged from 29.7 to 30.4 in the small and medium seed size varieties, respectively. RELATIONSHIP OF SEED SIZE WITH SURVIVAL PERCENTAGE Observations recorded on survival percentage of pulse beetle on the varieties of different seed size indicated that, there were no significant relationship of seed size and survival of the beetle. However, the survival percentage was ranged from 31.7 to 41.2 in the bold and medium size varieties, respectively. Percentage of seed infestation (Table 4.9) Significant difference was observed among different varieties of chickpea with regards to per cent seed infestation (Fig 6). Variety JG-16 had minimum percentage of seed infestation (36.9%), which was significantly less than rest of the varieties, except JG-130, JG-322 and JG-6. On the other hand variety RVS-201 recorded maximum per cent of seed infestation (60.3%, which was found significantly higher than the seed infestation in rest of the varieties, except JGK-43, RVS-202 and JG- 11.
Per cent loss in seed weight (Table 4.9) Per cent loss in weight was in the range of 25.41 to 33.30 in different varieties with significant difference among varieties (Fig 6). Significantly less per cent loss in seed weight was observed in variety JG-16 than rest of the varieties, except JG-130 and JG-322. On the other hand variety RVS-201 recorded maximum per cent loss in seed weight, but at par to JGK-43, RVS-202 and JG-11. Table 4.9: Per cent seed infestation and per cent loss in seed weight due to S. No. pulse beetle in different varieties of chickpea Varieties Percentage of seed infestation Per cent loss in weight 1 RVS-201 60.3 (50.94) 30.1 (33.30) 2 RVS-202 58.1 (49.70) 29.1 (32.62) 3 RVS-203 52.3 (46.30) 26.1 (30.73) 4 JG-6 41.3 (39.63) 20.7 (27.00) 5 JG-11 57.7 (49.45) 28.9 (32.50) 6 JG-16 36.9 (37.40) 18.4 (25.41) 7 JG-130 38.5 (38.33) 19.2 (25.98) 8 JG-322 39.9 (39.15) 19.9 (26.54) 9 JGK-1 43.4 (41.21) 21.7 (27.76) 10 JKG-3 45.4 (42.38) 22.7 (28.45) 11 JGK-43 59.5 (50.46) 29.7 (33.04) 12 JGG-1 52.2 (46.30) 26.1 (30.75) SE(m)± (0.95) (0.53) CD at 5% (2.80) (1.55) * Figures in parentheses are angular transformed values
Per cent seed infestation and per cent loss in seed weight 18.4 20.7 19.2 19.9 21.7 22.7 26.1 26.1 30.1 29.1 28.9 29.7 36.9 38.5 41.3 39.9 43.4 45.4 52.3 52.2 58.1 57.7 60.3 59.5 70 Fig 6: Per cent seed infestation and per cent loss in seed weight due to pulse beetle on different varieties of chickpea 60 50 40 30 20 10 0 RVS-201 RVS-202 RVS-203 JG-6 JG-11 JG-16 JG-130 JG-322 JGK-1 JKG-3 JGK-43 JGG-1 Varieties
Chapter- V DISCUSSION During the course of present investigations, influence of 12 varieties of chickpea having variation in seed size and seed coat colour was studied for their response to orientation, ovipositional preference, development and survival of pulse beetle, Callosobruchus maculatus. The seed infestation and loss in seed weight due to pulse beetle infestation were also recorded. The obtained data during present investigation are discussed herewith. The adult orientation on different varieties ranged from 6.0 to 10.3 with significant differences among them. Minimum adult orientation recorded on varieties JG-16 showed their less susceptibility for orientation of the pulse beetle except JGK- 43, JG-11, RVS-201, JKG-3, JG-130 and JG-322. On the other hand variety JG-6 were found most preferred for orientation of the beetle except RVS-203, JGK1, JGG- 1, RVS-202, JG-322 and JG-130. The egg deposition on different varieties under free choice condition ranged from 13.0 to 21.0 with significant differences among different varieties. Minimum and similar egg deposition on varieties JG-11 and JG-16 indicate that these varieties were less preferred by the beetle for egg deposition, except JGK-43, RVS-201, JKG- 3, JG-130 and JG-322. Whereas, maximum egg deposition on varieties except JGK- 43, RVS-201, JKG-3, JG-130 and JG-322 indicate their higher preferency for egg deposition by the beetle, except JGG-1, JGK-1, RVS-202, JG-322 and JG-130. The egg deposition on all the varieties under free choice condition was observed in correspondence to the orientation of the beetle on different varieties. The number of eggs deposited on different varieties under forced condition ranged from 45.0 to 115.3 with significant differences among them. Minimum egg deposition on variety RVS-201 indicated their less suitability for oviposition by the beetle. The egg deposition on varieties JGK-43, JKG-3, RVS-203 and JG-322 under free choice condition was less, whereas deposition of eggs in these varieties under forced conditions were comparatively higher. The less deposition in these varieties under free choice condition may be due to their less preferency for orientation by the beetle.