Spotted Wing Drosophila in the Western United States David Haviland- UC Cooperative Extension, Kern Co.
Spotted Wing Drosophila A vinegar fly Drosophila (like on a ripe banana) Not a true fruit fly like medfly Name derived from two spots on the wing of the male 3,000 sp. drosophilans in the world 175 sp. in N.A., 2 sp. harmful to crops SWD is one of them female male Photos: Martin Houser, CDFA
Martin Hauser, CDFA Drosophila suzukii Drosophila simulans
Spotted Wing Drosophila Origin Native to SE Asia/Japan In Hawaii since 1986 Do not know how it got to California California First found in coastal berries in 2008 Identification announced by CDFA in mid-2009 Spread throughout coastal areas Moved into the Sacramento Delta (cherries) Recovered in 23 counties by end of 2009 Other 2009 Movement Oregon- 13 Counties Washington- multiple counties British Colombia- Fraser Valley Florida- Multiple Counties
Primary host range in California raspberries blackberries cherries blueberries strawberries stone fruit (esp u-pick) Misc.
male female egg 350/female pupa 3-15 days Ø time for 1 generation 12 days 12-72h Laura Nilson 3-13 days 3rd instar larva Martin Hauser, CDFA 2nd instar larva 1 st instar larva
Females lay eggs under the pierced grape/cherry skin Egg Respiratory filaments Larvae hatch and develop inside
Maggots in fruit!! Damage
Economic damage Rotten, moldy fruit Lost yield Eggs cannot be sorted Maggot-infested berries sent to consumers Potential quarantines of fruit in export markets Hand-sorting in field Slow-down of harvest operations Culls left in the field for reinfestation Mechanical harvest could be problematic Infestation levels potentially at their highest Soft berries can be culled, maggot-infested berries could become a slimy mess Berries may not be good for anything
Components of an IPM Program Identification Monitoring Biology/Phenology Cultural controls Biological controls Chemical Controls Integration and Implementation
Components of an IPM Program Identification Monitoring Biology/Phenology Cultural controls Biological controls Chemical Controls Integration and Implementation - done by CDFA - not likely to help
Monitoring for larvae Sugar Flotation Method
Monitoring- develop a trap Principles Easy to use Easy to make Supplies readily available Stackable Durable Large opening to maximize volatilization of bait and captures Bait Apple cider vinegar Cheap, clear, effective
SWD trap design and bait studies Clear Commercial Haviland Evaluations of baits ACV, yeast, other attractants Modified Haviland Van Steenwyk Red Evaluations of trap size, shape, color, orientation of openings, etc.
Picture-wing flies (Otitidae) SWD and look-alikes in Kern Co. traps Vinegar flies (Drosophilidae)
Trap type Monitoring keypoints Mean (±SE) SWD per trap per week 120 100 80 60 40 20 0 Bait type Week 1 Week 2 Lure TRE0886 + Antifreeze TRE0890 + Antifreeze TRE0891 + Antifreeze TRE0919 + Antifreeze Lure + ACV ACV ACV TRE0890 + ACV TRE0891 + ACV TRE0919 + ACV Lots of traps are effective large openings traps can match environment Multiple baits work ACV or yeast effectiveness increased with soap lures being developed Pick a trap/lure and stick with it
Lures for SWD Capture rate Specificity
Phenology Studies Weekly monitoring of adult SWD 20+ traps monitored weekly since 2010 Monitoring in cherries, citrus and blueberries Apple cider vinegar in Haviland trap Count males and females Correlate catches to crop phenology and weather
Phenology in Kern County Cherries 80 70 D. suzukii per trap per week 60 50 40 30 20 10 0 1 Jan 31 Feb 61 Mar 91 Apr 121 May 151 Jun 181 Jul 211 Aug 241 Sep 271 Oct 301 Nov 331 Dec 361
Washington SWD in Cherries (http://www.tfrec.wsu.edu/p ages/swd)
Central Coast, Ventura Co.
600 D. suzukii per trap per week D. suzukii per trap per week D. suzukii per trap per week 2010 Citrus 2010 Cherry 2010 Blueberry 500 2011 Citrus 2011 Cherry 2011 Blueberry 2012 Citrus 2012 Cherry 2012 Blueberry 400 300 200 100 0 80 1 31 61 91 121 151 181 211 241 271 301 331 361 70 60 50 40 30 20 10 0 10 1 8 31 61 91 121 151 181 211 241 271 301 331 361 6 4 2 0 1 31 61 91 121 151 181 211 241 271 301 331 361 Julian date Kern County trapping Overwinters in citrus Moves to cherries in the spring Catches approach zero in early July Flies return around October 1 Flies reduced in Dec/Jan
Central Valley/ Southern SJV Avg. D.,suzukii per trap per week 250 200 150 100 50 Citrus Cherry Blueberry 0 1 6 11 16 21 26 31 36 41 46 51 Week of the year
Field Validation- transect study 2011 3-spray program Normal harvest 2012 2-spray program 10% of normal harvest
a Adult movement Initially in only citrus b Movement initiated about 1-2 weeks before color change starts Flies move very quickly Edge effect to about 600 ft c d Insecticides reduced flies during pink color (3x insecticides) No fly activity during cherry harvest in either crop Fig. 2. Captures of SWD in a transect of bucket traps placed perpendicular to the interface between citrus and citrus orchards during four time periods prior to cherry harvest. Data show a) that SWD is primarily in citrus while cherry fruit are green from 20 Feb to 21 Mar, b) that SWD moves to cherries during the period of early color development in late March to early April, c) SWD populations once insecticide treatments begin in cherries, and d) SWD populations when insecticide treatments when bo cherries and citrus have been treated with insecticides.
a. Citrus 100% 336 :338 Male Female 107 :134 57 :97 71 :94 Sex ratios Percenage SWD by gender Percentage SWD by gender 80% 60% 40% 20% 0% b. Cherries 100% 2 :9 0 :16 4 :14 63 :173 80% 60% 40% 20% 0% 6 Mar 14 Mar 21 Mar 27 Mar 1 2 3 4 Weeks after initiation of color change in cherries Overwintering population almost exactly 50:50 male to female First flies to migrate to cherries on 6 Mar, 14 Mar and 21 Mar were 82, 100 and 78% female Evaluations of bucket traps based on male captures can result in false negatives Corrections involve counting females or placing traps outside of the cherry orchard
Seasonal movement of SWD Mean (±SE) SWD per trap per week 60 50 40 30 20 10 Cherry (n=10) Stone Fruit (n=8) Citrus (n=3) Shaded Lawn (n=3) Riparian (n=2) 0 Summer Fall Winter Janet Caprile, Delta Region, CA
Lee, Bruck, Curry, Edwards, Haviland, Van Steenwyk, and Yorgey, 2011 Ripeness and Susceptibility Brooks Tulare No- Choice Choice
Monitoring and Phenology take-home messages Traps are effective, use them Several options for trap type and bait Pick one and be consistent Trapping in cherries Mostly used for presence/absence sampling Determine if insecticides are wearing down Trapping in alternate hosts Determine what might be coming How to count traps Counting males is usually okay Count females 2 weeks before straw through pink SWD attracted to cherries starting just before straw stage Cherries susceptible straw stage through harvest No need to manage SWD while fruit are green No need to manage SWD after harvest
Control Programs Cultural controls Humidity (irrigation type, floor cover) Sanitation (crops with long harvest) Early harvest (not usually possible) Varieties (similar susceptibilities) Biological controls Pupal parasitoid prevalent Valuable in alternate hosts To reduce population, not to protect crop Susceptible to insecticides Exploration continues Chemical controls Insecticides effective Issues related to insecticide use close to harvest
Chemical Control of SWD
Chemical control Efficacy OPs, pyrethroids, spinosyns Neonics not effective Primarily work as adulticides Some kill eggs on fruit surface Assume 7 days of effectiveness Regulatory constraints Preharvest and reentry intervals MRLs Other caveats Insecticides never needed in the past MRLs in the past a mute point Packers often dictate what growers do Packers 250 miles away EILs don t exist ($40,000 crop, $120 = 3 sprays) Initial extension publications equaled laundry lists Efficacy ratings and PHIs
Premises of a chemical program OPs, Pyrethoids and Spinosyns are effective Control for 7+ days achievable with an application Cherries susceptible from straw through harvest Flies move to cherries at straw Cherries susceptible for 3 weeks, then during harvest Keep targeting adults as the immigrate Drosophilans known for resistance Rotate insecticides Maintain exportability of fruit MRLs must be compatible Use low Malathion rates to avoid phytotoxicity Must adhere to PHIs Warrior II (14d), Delegate (7d), Malathion (3d), etc.
Current Recommendations for a Chemical Control Program 3-spray program (high pressure) 21 days before harvest- Warrior II or Danitol 10-14 days before harvest- Success 3-7 days before harvest- Malathion (1.5pt) 2-spray program (low pressure) 21 days before harvest- Warrior II or Danitol 7 days before harvest- Success or Malathion Determine the need of a 3- or 2-spray program based on neighboring crops and monitoring
Thank you