Dispersal and Orientation of Sterile Ceratitis capitata and Anastrepha ludens (Tephritidae) in Chiapas, Mexico

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Abstract
(1) Six releases of sterile Meditterranean fruit-fly (Ceratitis capitata (Wiedemann)) and one of Mexican fruit-fly (Anastrepha ludens (Loew)) were made in coffee and mango plantations in Chiapas, Mexico. Traps were arranged in a regular array around the release point; data were treated to produce standard and 95% confidence ellipses of daily fly positions. (2) In all cases mean fly position moved significantly from the release point indicating drift of the released population; most movements were towards the north and east, the direction of prevalent daily winds. (3) The pattern of trapped flies was significantly different from a circular distribution on 23 out of 37 experiment days and orientation sometimes changed markedly from day to day. These translational and rotational movements of the released flies appeared to be independent of each other. (4) Area of successive standard ellipses calculated for consecutive days after release, indicated that flies spread out over a greater area in an approximately linear fashion with respect to time in most cases. (5) A combined release of C. capitata and A. ludens showed significant differences between the two species, the latter tending to spread out less rapidly. The results suggest that the techniques employed might make a sensitive test for quality of mass-reared flies.