OVIPOSITION BEHAVIOR OF LABORATORY-REARED AND WILD CARIBBEAN FRUIT FLIES (ANASTREPHA SUSPENSA; DIPTERA: TEPHRITIDAE): I. SELECTED CHEMICAL INFLUENCES

Comparative studies of the oviposition behavior of wild Caribbean fruit flies and of a strain reared in the laboratory for over 100 generations revealed significant differences in their responses to certain physical characteristics of the oviposition site. In choice tests using white and black artificial oviposition domes, the wild flies selected black domes almost exclusively, but the laboratory-reared (LR) flies failed to show any preference. When given a choice between domes and flat oviposition substrates (both black), the wild flies displayed an almost absolute preference for domes, whereas the LR flies deposited nearly 12% of their eggs into the flat discs. White domes and black plates were accepted at an equal rate by the LR flies, but the wild flies rejected both substrates almost completely. A physical stimulus hierarchy thus appears to exist, with convex shape being important to the wild flies, and darkness being of secondary but still considerable importance. Reductions in shape and color discrimination by the LR flies may be the result of genetic selection associated with use of behaviorally inappropriate oviposition units during colonization and mass rearing. The oviposition rate of the LR flies was considerably greater than that of the wild flies under all conditions tested, indicating either that the fecundity of the LR flies was innately greater or that their threshold for oviposition under the laboratory conditions was somewhat lower. The implications of these findings are discussed in relation to improving colonization and mass-rearing techniques so as to better retain wild-type characteristics in the laboratory population. RESUME COMPORTEMENT DE PONTE DES FEMELLES D'ANASTREPHA SUSPENSA (DIPTERE: TEPHRITIDAE) SAUVAGES OU PROVENANT DU LABORATOIRE: II INFLUENCES PHYSIQUES PARTICULIERES La comparaison du comportement de ponte d'Anastrepha suspensa sauvages et d'une souche elevee au laboratoire pendant plus de cent generations (LR), a permis de constater des differences significatives aux reponses a certaines caracteristiques physiques du lieu de ponte. Avec des tests utilisant comme pondoirs artificiels, des domes noirs et blancs, les sauvages choisissent presque uniquement les domes noirs tandis que les mouches LR ne manifestent aucune preference. Ayant le choix entre domes et surfaces planes (tous deux noirs), les sauvages preferent presque exclusivement les domes, tandis que les LR pondent environ 12% des œufs sur les plaques planes. Les mouches LR acceptent autant les domes blancs et les plaques noires, tandis que les sauvages refusent presque totalement les deux. Une hierarchie des caracteristiques physiques apparait, ainsi ou la forme convexe a le plus d'importance pour les mouches sauvages, et ou la couleur noire, bien que secondaire, a une influence toujours significative. La reduction de la discrimination de la forme et de la couleur chez les mouches LR pourrait etre le resultat d'une selection genetique provoquee par l'utilisation de pondoirs inadequats pendant l'elevage et la production de masse.