Effect of combined insecticide sprays and sanitation techniques on population dynamics of Ceratitis capitata (Diptera: Tephritidae) in the central mountains of Israel

We conducted an environmental manipulation study over a 7-km² area to examine the effect of different control levels on the population dynamics of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) in the central mountains of Israel. Adult male monitoring was carried out from spring to fall during 1988-1991 and year-round from 1994 to 2001. From 1995 to 1997, we manipulated the study area, imposing different levels of control by using a combination of insecticide sprays, tree pruning and removal, and fruit stripping. In the years preceding the manipulation, population dynamics was characterized by a peak summer population size in June-July, followed by a population decrease in August, leading to an early fall peak in September-October. If flies overwinter locally, we expected the intensive control to decrease the early summer population after the control. If flies do not overwinter locally, the control and sanitation activities should not decrease the population level in the following summer. During the entire period discussed, no flies were captured between January and May. The first appearance was recorded in late May or early June, reaching a peak in July. Regardless of control level and extent, the early summer peak remained unchanged during the entire study period, whereas the later fall peak decreased as host density decreased. We suggest that the first peak is the result of a seasonal reinvading population, whereas the later peak is governed by host availability and multiplication of the invading flies. The meaning and possible practical implications of our findings are discussed.