Can Sprays of Fatty Acids Repel 

 Plum Curculios? 



Tracy Leskey', Catherine Bramlage^ Larry Phelan^, 



and Ronald Prokopy^ 



^Department of Entomology^ University of Massachusetts at Amherst 



^Ohio Agricultural Research and Development Center 



Some insects seem to be able to recognize same- 

 species death, possibly because of the presence of 

 unsaturated fatty acids in the remains. This recog- 

 nition has been shown by research with cockroaches, 

 ants, and earwigs. Conceivably, unsaturated fatty 

 acids may be useful as a pest-control agent. Here, 

 we applied different concentrations of unsaturated 

 fatty acids (oleic, linoleic and linolenic) dissolved in 

 methanol to freshly picked wild plums to determine 

 if these substances would repel feeding or oviposi- 

 tion by adult female plum curculios. 



Wild plums were picked from trees located on 

 the campus of the University of Massachusetts and 

 brought directly to the laboratory. Fatty-acid solu- 

 tions were made from oleic, linoleic and linolenic 

 acid dissolved in methanol at four concentrations: 

 10.0 mg/ml, 1.0 mg/ml, 0.1 mg/ml, 0.01 mg/ml. 

 Twelve replications at each concentration were pre- 

 pared. For each replicate, the treated plum was 

 coated with a fatty-acid solution. The control plum 

 was left uncoated. A treated and an untreated plum 

 were placed under a small plastic cup together with 

 one adult female plum curculio. Each adult was 

 able to forage freely on either the treated or un- 

 treated plum. Plums were checked 24 hours later 



for evidence of feeding or oviposition. Numbers of 

 plums with feeding and oviposition scars were 

 counted for each replicate. 



Contrary to our proposed hypothesis, it appears 

 from our results that applications of fatty acids on 

 the surface of wild plums did not reduce feeding or 

 oviposition by adult female plum curculios (Table 

 1). Although other insect species may recognize fatty 

 acids present in dead individuals and be repelled 

 by such compounds, plum curculio adults in our 

 laboratory have been observed to crawl over and 

 feed in close proximity to such individuals. The fatty 

 acids tested here do not appear to elicit a repellent 

 response in plum curculio and have little or no prom- 

 ise as control agents for this important pest. 



Acknowledgments 



This work was supported by grants from the 

 USDA Sustainable Agriculture Research and Edu- 

 cation Program (SAKE), the USDA Northeast Re- 

 gional IPM Competitive grants program, and the 

 New England Tree Fruit Growers Research Com- 

 mittee. 



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10 



Fruit Notes, Winter, 1996 



