INTRODUCTION OF ALLORHOGAS PYRALOPHAGUS MARSH (BRACONIDAE) IN LAMPUNG (INDONESIA) WITH PRELIMINARY NOTES Oh, ITS BIOLOGY

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1 Entomology I INTRODUCTION OF ALLORHOGAS PYRALOPHAGUS MARSH (BRACONIDAE) IN LAMPUNG (INDONESIA) WITH PRELIMINARY NOTES Oh, ITS BIOLOGY Ubandi Harsanto and Sunaryo Research Division, P.T. Gunung Madu Plantations, Lampung, Indonesia ABSTRACT Allorhogas pyralophagus Marsh (Braconidae), a larval ectoparasite of Eoreuma loftini (Dyar) (origin Mexico), was introduced from the PARC-CIBC Station, Commonwealth Institute of Biological Control, Rawalpindi, Pakistan through the Indonesian Sugar Research Institute, Pasuruan to Gunung Madu Plantations, La'mpung in 1982 for trial against Tryporyza nivella (F). In the laboratory the life cycle is completed in 17.4 days. Females live 9.3 days laying 48.6 eggs and parasitising 6.6 host larvae. More than adults have been released so far and have been recovered repeatedly. However, its parasitism is low. INTRODUCTION This gregarious larval ectoparasite was recorded parasitising Eoreuma (Acigona) loftini (Dyar) in Johnson grass (Sorghum halapense) (Bennett et al.]), and has been described as Allorhogas pyralophagus by Marsh4. It was introduced to Indonesia from the PARC-CIBC Station, Commonwealth Institute of Biological control, Rawalpindi, Pakistan, through the Indonesian Sugar Research Institute (ISRI), Pasuruan, East Java, and it was brought to Gunung Madu Plantations (GMP), Lampung in June 1982 for trials against sugar cane top borer Tryporyza nivella (F.). It has been mass reared and released since August, Observations on its biology and releases are reported here. MATERIALS AND METHODS A culture of Allorhogaspyralophagus was established on field collected larvae of the top borer Tryporyza nivella. Fifteen stems with full-grown larvae, after removing leaf sheaths, were exposed to 15 females of the parasite in glass tubes measuring 10 cm x 24 cm. Fresh stems with larvae were replaced every second day. Keywords: Sugar cane borer, Allorhogaspyralophagus Marsh, Introduction and biology, Lampung (Indonesia).

2 The stems with parasitised larvae were kept in trays. They were dissected after seven days and cocoons were collected and put in plastic tubes measuring 6 cm x 8 cm for emergence of adults. The adults were kept in muslin cloth cages for one or two days before they were released in the field. RESULTS Biology Biology of Allorhogas pyralophagus has been studied by Bennett et al.1 and by Pramono and Wirioatmodjos. Observations1 made at GMP are given below: Soon after mating the females try to oviposit by drilling into the stem and may continue trying for a long time. If they fail to drill successfully, they become exhausted and give up oviposition. When successful, they oviposite with the ovipositor directed forward. Even when the cocoons are exposed if the larva is beyond the reach of the ovipositor, the females cannot parasitise it. The females start laying eggs one day after emergence and live for 4-18 (mean 9.3) days and lay (48.6) eggs during this period. They parasitise 3-13 (6.6) host larvae and lay 1-23 (7.4) eggs on one larva. Most of the eggs are laid in the first three days. At 27.5 "C and 79.5% r.h. incubation is 1-2 days, larvae complete development in 6-8 days and the pupal stage lasts 7-12 days. Development from egg to adult is completed in (17.4) days. The adults emerge by cutting holes in the sugar cane stems and leaf sheaths. Up to seven holes were found in the stem and three in the leaf sheaths surrounding it. The circular holes measured (0.81 j mm. Up to 20 females and 12 males emerge in this way from one stem. Effect of host position on parasitism To determine the effect of the position of the host larva in the sugar cane stem on degree of parasitism, field collected fifth-instar larvae of the top borer were offered to parasite females in (a) natural condition, (b) half of the leaf sheaths were removed to expose the moth exit-hole, and (c) leaf sheaths completely removed to expose both the moth exit-hole and the cocoon. Twenty larvae in each condition were exposed to 15 females and 10 males in a screen cage (60 cm x 30 cm x 60 em) for 12 days. It was replicated five times. The result showed that parasitism by A. pyralophagus was significantly increased when the exit hole or cocoon were exposed. (Table I). l d Host suitability In the laboratory, A. pyralophagus has been reared successfully on Chilo spp. in Pakistan (Mohyuddin, A.I Pers. comm., PARC-CIBC Station, Commonwealth Institute of Biological Control, Rawalpindi, Pakistans) and on Diatraea spp. in Trinidad (des Vignes2).

3 UBANDI HARSANTO AND SUNARYO 565 TABLE I. Parasitism of Allorhogaspyralophagus on Tryporyza nivella larvae when offered in three different conditions in the host plant Host condition Number of Parasitism larva parasitised 1 Natural condition a Moth exit-hole exposed b Moth exit-hole and cocoon exposed b Numbers followed by the same letter are not significantly different LSD 0.05 = a stem borer Chilo auricilius ~ udg. were used. Field collected larvae of the top borer in cane tops after removing leaf sheaths, and the stem borer in tunnels made in half split canes covered with fine perforated plastic sheets, were exposed to 10 females, one day after emergence, in glass tubes measuring 10 cm x 24 cm for 48 hours. Number of larvae parasitised, cocoons produced and adults emerged was higher on the top borer than on the stem borer. The size of females on top borer was also significantly larger than on stem borer. (Table 11). TABLE II. Number of larvae parasitised, cocoons produced and adult size of Allorhogas pyralophagus on Tryporyza nivella and Chilo auricilius, based on 40 larvae of each species No. of larvae No..of cocoons Adults Mean adult Host species parasitised size (mm) Range Mean emerged (%) (%) Male Female T. nivella a 80.5 a 3.2 a 4.2 a C. auricilius b 42.1 b 3.0 a 3.4 b -- Numbers followed by the same letter are not significantly different at 5% level Competition between A. pyralohagus and Elasrnus zehqtneri Ferr. To study competition between A. pyralophagus and the local larval ectoparasite E. zehntneri, 30, fifth-instar field collected larvae of the top borer, after removing leaf sheaths, were offered to 15 females of each of the two species together in a glass tube measuring 10 cm by 36 cm, until the females died. It seems that both of them can coexist without interfering with each other because the same number of larvae were parasitised by each of these species. Only one larva was parasitised by both species and both completed development on it. However, the number of pupae produced by A. pyralophagus was lower than E. zehntneri (Table 111). Release and recovery Release of A. pyralophagus was started in August 1982 and females and males have been released so far. In December 1982 it was recovered

4 566 ENTOMOLOGY in small numbers. In 1983 it was recovered from 0.24% to 0.63% of larvae of the top borer in different months. In 1984 monthly releases were made at the rate of 100, 200 and 300 females per hectare from August to November. Surveys for the recovery were made at the release sites and surroundings. Full-grown larvae of the top borer were collected and reared in the laboratory. It was not recovered where release was made at the rate of 100 females. Where releases were made at the rate of 200 females, it was recovered from 5.9% larvae in September and where 300 females were released it parasitised 2.5% larvae in October, 5.9% in November, 4.3% in December 1984 and 6.2% in January After this the cane was harvested. The parasite was recovered up to 1.5 km away from the release site and was recovered from Chilo sacchariphagus as well (Boj.) as T. nivella. TABLE Ill. Number of larvae parasitised and pupae produced by Allorhogas pyralophagus and Elasmus zehntneri on 30 larvae of Tryporyza nivella exposed to both species together No. of larvae No, of pupae producedl Parasite species parasitised host larva A. pyralophagus E. zehntneri A. pyralophagus and E. zehntneri t 9 " * Three cocoons of A. pyralophagus and 9 pupae of E. zehntneri were produced. CONCLUSION All the three sugar cane borers found at GMP Tryporyza nivella, Chilo auricilius and C. sacchariphagus are suitable hosts for Allorhogas pyralophagus. Although C. sacchariphagus was not tested in the laboratory, the parasite was recovered from it in the field. However, T. nivella seems better for its development, most probably, because of its bigger size and sluggish habits. The females developed on it were also bigger in size and \hey may have higher fecundity. Prelimi'nary studies indicate that it can coexist with the local larval ectoparasite Elasmus zehntneri. Their combined effect may be additive and higher parasitism of the borers may be achieved. The life cycle of A. pyralophagus is shorter than that of the top borer which is about days (Kalshovens). The parasite can complete about three generations during one generation of the host and thus has the potential to build up higher populations. However, accessibility of the host for oviposition seems to limit its population build up (Mohyuddins). ~ollowin'~ its introduction, A. pyralophagus was recovered a number of times. It gradually built up its level of parasitism which was highest three months after releases were stopped. It is too early to say whether or not it is established, therefore, further releases are warranted.

5 UBANDI HARSANTO AND SUNARYO 567 ACKNOWLEDGEMENT The authors are much indebted to Dr Soeprapto Mangoendihardjo, Department of Plant Protection, Faculty of Agriculture, Gadjah Mada University, Yogyakarta, Indonesia and to Dr A.I. Monyuddin, PARC-CIBC Station, Commonwealth Institute of Biological Control, Rawalpindi, Pakistan for their invaluable guidance on conducting the study and going through the manuscript. REFERENCES 1. Bennett, F.D., Cock, M.J.W. and Diaz, C.F.A. (1983). Allorhogas sp. n. (Braconidae) a potential biological control agent for graminaceous stem borer from Mexico. ISSCT Entomology Newsletter, 14: , des Vignes, w.g. (1983). Rearing, release and recovery of Allorhogas sp. n. (Hymenoptera; Braconidae) - a potential biological control agent of Diatraea spp, in Trinidad. ISSCT Entomology Newsletter, 14: Kalshoven, L.G.E. (1981). Pests of Crops in Indonesia. Revised and translated by P.A. van der Laan, P.T. Ichtiar Baru-Van Hoeve, Jakarta, 701 pp. 4. Marsh, P.M. (1984). A new species of Braconidae (Hymenoptera) from Mexico introduced in Texas to control a sugar cane borer, Eoreuma loftini (Lepidoptera: Pyralidae). Proc. Entomol. Soc. Washington, 86: Mohyuddin, A.E. (1985). Report on visit to Indonesia to advise on management of sugar cane pests. PARC-CIBC Station, Commonwealth Institute of Biological Control, Rawalpindi, Pakistan, 11 pp (mimeographed). 6. Pramono, D. and Wirioatmodjo, B. (1983). Biologi Allorhogas sp. parasit untuk penggerek tebu. Pertemuan Tehnis BP3G Pasuruan, 11 pp.