Identity and biology of Aganaspis daci (Weld) (Hymenoptera: Figitidae), recently introduced to Egypt for biological control of Bactrocera zonata (Diptera: Tephritidae)

Abstract

The peach fruit fly, Bactrocera zonata (Saunders, 1841), (Diptera: Tephritidae), is a serious polyphagous pest of tropical and subtropical fruits. In Egypt, the fly was first detected in 1997 and has since become widespread over most of the Egyptian provinces, causing serious damage to many fruit crops, particularly mango, guava, peach, apricot and citrus. In 2008, the larval-pupal koinobiont endoparasitoid, Aganaspis daci (Weld, 1951) (Hymenoptera: Figitidae, Eucoilinae) was introduced to Egypt via Hawaii for evaluation. The parasitoid is a dominant natural enemy of several Bactrocera species from Southeast Asia, the native region of B. zonata. To evaluate the potential of A. daci for biocontrol of B. zonata, this study investigated distinguishing features of A. daci in different stages, developmental periods, reproductive output, and optimal rearing protocols under laboratory conditions of 25 ± 1°C, 54 – 65% RH, and 14L:10D photoperiod, using B. zonata as hosts. The parasitoid Aganaspis daci went through four instars and developed into the ectoparasitic phase late in the third instar, as the larva developed one pair of functional thoracic spiracles. Total developmental period averaged 23.3 days, and males eclosed two days earlier than females. Realized fecundity of mated females averaged 39.6 offspring per female (range 32 – 55) and progeny sex ratio was 1:1. Longevity of honey fed females and males averaged 18.8 and 17.3 days, respectively. A. daci showed relative potential as a biological control agent against B. zonata in Egypt and was propagated for several generations before it was approved for release in 2009. Field recovery was reported one month following its liberation in guava orchard at Al-Arish district, North Sinai Province, with 1.6 – 8% initial rate of parasitism. Further studies, on its adaptation to the new Egyptian environment and efficacy against B. zonata under field conditions are in progress. This study provides important baseline information on the morphological and biological attributes of A. daci and the rearing method provides a basis for the development of a mass rearing protocol for augmentative parasitoid releases.