Title: Effect of surround WP on behavior and mortality of the apple maggot (Diptera: Tephritidae) Authors
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 21, 2009
Publication Date: April 1, 2010
Citation: Leskey, T.C., Wright, S.E., Glenn, D.M., Puterka, G.J. 2010. Effect of surround WP on behavior and mortality of the apple maggot (Diptera: Tephritidae). Journal of Economic Entomology. 103(2):394-401. Interpretive Summary: The apple maggot fly is a serious pest of apple in eastern North America. The development of Surround WP, a processed kaolin clay material, offers an alternative to conventional insecticides for managing apple maggot fly in apple orchards. We conducted studies aimed at understanding why this inert material was effective against foraging apple maggot flies. We found that the white coating of Surround WP reduced or greatly eliminated the well-defined visual cues which flies rely upon to locate these host apples within trees canopies, i.e. the color and shape silhouette of the ripening fruit. Flies also were deterred by the presence of Surround WP; flies spent more time grooming and less time foraging when they were introduced to Surround WP-treated surfaces. Exposure to Surround WP particles also resulted in increased mortality of apple maggot fly and to the closely related walnut husk fly, likely because particles adhered to mouthparts or other body parts, reducing the abilities of flies to perform necessary activities or functions such as feeding. These results are valuable for apple growers to control apple maggot fly.
Technical Abstract: The apple maggot fly, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae), is a key pest in apple production areas located in the northeastern and midwestern United States and the eastern provinces of Canada. The development of Surround WP has offered a new approach for controlling apple maggot fly and other tephritid species, as this material is considered to be compatible with advanced IPM and organic production systems. We conducted studies aimed at identifying the behavioral and biological effects of this material on apple maggot flies. Specifically, we examined the effect of Surround WP on the visual ecology of adult flies under field conditions, on tactile responses of flies in semi-field trials, and on fly mortality in laboratory-based bioassays. Using fruit-mimicking spheres, we demonstrated that an even coating of white particles over the sphere surface reduced visual attractiveness of the fruit mimic. We also found that spotty-coated fruit-mimicking spheres (meant to mimic ripe fruit bearing an uneven coating of Surround WP), were perceived by flies as not having the ideal round silhouette shape stimulus due presumably to the uneven coloration and reflective light intensity of the sphere surface. Surround WP served as a strong tactile deterrent; females spent less time foraging and resting on treated fruit and a greater proportion of time engaged in grooming activity compared with untreated fruit. Surround WP also had a toxic effect on both apple maggot and walnut husk flies, R. suavis (Loew); flies exposed to and forced to stand on Surround-treated surfaces died in less than two days in all trials. The combined effectiveness of Surround WP is based on a reduction in the attractiveness of fruit-based visual cues, an increase in the likelihood of flies leaving Surround-treated surfaces due to tactile deterrence, and a potential for increased mortality due to exposure to Surround WP particles.