SIDE-EFFECTS OF INSECTICIDES USED IN TOMATO FIELDS ON THE EGG PARASITOID TRICHOGRAMMA-PRETIOSUM RILEY (HYM., TRICHOGRAMMATIDAE), A NATURAL ENEMY OF TUTA-ABSOLUTA (MEYRICK) (LEP., GELECHIIDAE)

Trichogramma pretiosum Riley is an important natural enemy used for th e biological control of Tuta absoluta in tomato fields in several coun tries in South America. The side-effects of insecticides on T. pretios um was tested by dipping parasitized host eggs (Ephestia kuchniella Ze ller) at three different development stages (egg-larvae, pre-pupae and pupae)in pesticide solution at recommended concentrations. The insect icides varied in their toxicity and significantly affected the develop ment time of the immature stages, emergence, parasitism and longevity of the adult parasitoid. Cartap and phenthoate were harmful and caused total mortality in all the experiments in the three stages of develop ment tested. Lambda-cyhalothrin was not detrimental but caused a signi ficant increase in mortality, prolonged development of the immature st ages and decreased the capacity of parasitism of the emerged females. Tebufenozide, teflubenzuron and abamectin had sublethal effects. They reduced the time of development, especially when applied during the pu pae stage. The capacity of parasitism of emerged females decreased and was affected by the stage of development treated. With abamectin trea tments, parasitism decreased as the development of the parasitoid adva nced and the mortality of the emerged adults from host eggs treated du ring the pupae stage was significantly higher. Tebufenozide reduced pa rasitism when applied during the egg-larval and pre-pupae stages. The results showed that cartap and phenthoate were harmful, lambda-cyaloth rin and abamectin were intermediate, tebufenozide and teflubenzuron we re harmless to slightly harmful. Nearly all the chemicals tested had s ignificant sublethal effects.