Psyttalia lounsburyi (Hymenoptera: Braconidae), potential biological control agent for the olive fruit fly in California

The African parasitoid Psyttalia lounsburyi (Silvestri) was evaluated as part of a classical biological control program directed at the olive fruit fly, Bactrocera oleae (Rossi), in California, USA. Experimental assessment using three non-target species provided some evidence that P. lounsburyi restricts its host use to B. oleae. Female P. lounsburyi preferentially searched olives infested with mature third-instar B. oleae, over other non-target plants, but most offspring were reared from olives containing younger (second through young third instar) B. oleae larvae. Developmental time (egg to adult) and adult longevity were significantly affected by temperature and sex, with males tending to develop faster and females living longer, especially in the lower ranges of temperatures tested. The mean longevity of adult female P. lounsburyi was greatest when honey was available and lowest when they were provided water alone or nothing. The presence of hosts significantly decreased longevity. Females produced an average of 10.2 ± 2.6 progeny during their lifetimes, which was lower than expected for a parasitoid adapted to B. oleae and may be a consequence of increased fruit size—the result of cultivation and selection—reducing parasitoid effectiveness on cultivated vs. wild fruit, as well as constraints on oviposition behavior imposed by experimental design. The results are discussed with respect to the use of P. lounsburyi as a biological control agent for olive fruit fly in California.