Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2002
Publication Date: July 30, 2002
Citation: Yee, W.L. 2002. Daily and seasonal activity patterns of Rhagoletis indifferens (Diptera:Tephritidae) in Washington state. Annals of the Entomological Society of America. 95:701-710. Interpretive Summary: Western cherry fruit fly is the major pest of cherries in Washington State and the Pacific Northwest. Before newer approaches to fly control can be adopted, a more thorough understanding of fly ecology and behavior is needed. USDA-ARS personnel at the Yakima Agricultural Research Laboratory in Wapato, Washington, conducted a detailed study of fly activity patterns in Yakima County, WA from June through July 2001. Male and female flies showed distinct behavior characteristics. Males spent most of their time on fruit, apparently waiting for females with which to mate. Females spent an equal amount of time on leaves and fruit, probably because they need to feed on the leaves more than do males. In general, no time of day or seasonal changes in these patterns were seen. Flies were most active when in was 80-95°F, usually during the afternoon. Flies of both sexes moved among tree quadrants during the day, their movement dictated by temperature and the sun's rays. Information from this work can be used to develop better ways to use cover sprays and to use safer products than are currently employed to control the fly. The fact that female flies spent a good deal of time of leaves, apparently feeding, suggests that control can be targeted there, perhaps by use of products that adhere to leaves and not to fruit, or by products that can be taken up by leaves and exuded from their surfaces. In addition, short-lived insecticides can be used when flies are most active, during noon hours. Since flies are most actively foraging during these times, they are more likely to contact the insecticides. The movement of flies within trees indicates that trapping and spray efficacy can be improved when flies are concentrated in one area within a tree.
Technical Abstract: The diurnal and seasonal activity patterns of the western cherry fruit fly, Rhagoletis indifferens Curran, were determined on three sweet cherry trees, Prunus avium (L.), from 0700-1900 hours during June through July 2001 in Yakima County, Washington. There were significant effects of time of day and season on numbers of flies seen on fruit relative to leaves. When temperatures were 15-16°C at 0700 hours in early June, flies of both sexes were seen mostly on leaves, but when the temperature reached 20°C, more flies of both sexes moved onto fruit. Peak fly sightings occurred at 25-35°C, usually after 1000 hours. At >35°C, most flies vanished from view and those seen were less active. Over the entire season, males were seen four times more often than females and spent more time on fruit than on leaves. Females were seen equally on and spent equal time on fruit and leaves when temperatures were 20 to 35°C. Mating was initiated on fruit, but was completed on both fruit and leaves. The correlation between overall fly sightings and daily temperatures depended on temperatures and season. Early in the season, when it was cooler, it was positive; in the middle of the season, there was no correlation; and in late season, when it was warmest, it was a negative. The results show that R. indifferens presence and times spent on fruit and leaves were greatly altered by daily and seasonal changes in temperature but they also suggest that at 20 to 35°C substrate-seeking behaviors of each sex do not change with time of day or season.