Biology, rearing and field release on Guam of Euplectrus maternus, a parasitoid of the fruit-piercing moth, Eudocima fullonia

Abstract

The eulophid parasitoid, Euplectrus maternus, is a gregarious ectoparasitoid of the larvae of thefruit-piercing moth, Eudocima (Othreis) fullonia. This parasitoid is indigenous to India and was released into Guam in 1998–99 to aid in the biological control of E. fullonia, an important pest of ripeguava, banana, mango, pomegranate, litchi,papaya, tomato, orange and other fruit crops.In the laboratory, biology and rearing of E. maternus on the larvae of E. fulloniawere studied. In no-choice tests, ovipositionby E. maternus was significantly greateron first and second instar larvae than on thirdinstar larvae. However, in free-choice tests,oviposition by E. maternus wassignificantly greater on second instar larvae,followed by first and third instar larvae. Thisparasitoid did not lay eggs on later instars,either in no-choice or free-choice tests.Females laid a significantly greater number ofeggs (>80%) on the dorsal surface of thelarvae than on either lateral or ventralsurfaces (1 to 8%). In general, more eggs werelaid on abdominal segments 1–3 on larvalinstars one to three. The survival of theimmature stages (from egg to adult) of E. maternus on second instar E. fullonialarvae was 61%, which was significantlygreater than the survival rates on first andthird instar larvae (32% and 26%), indicatingthat second instar host larvae are ideal formass rearing of the parasitoid. Mated femaleE. maternus continuously laid eggs on thesecond instar larvae of E. fullonia forup to 30 days, but the greatest number of eggswere laid during the first week after exposure.When E. maternus laid more than two eggson host larva, more female progeny wereproduced, indicating female-biasedreproduction. Adult parasitoids lived longerwhen fed with a honey: water (50% w/v)solution than with pure honey. Similarly, thefecundity of females increased significantlywhen fed with the honey-water solution whencompared to feeding with pure honey. To date,E. maternus has not established in Guam.