The biology of Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae), a parasitoid of the red gum lerp psyllid (Hemiptera: Psylloidea)

The red gum lerp psyllid, Glycaspis brimblecombei Moore (Hemiptera: Psylloidea), is native to Australia, where it feeds upon Eucalyptus species. It first appeared near Los Angeles, California, in 1998, and soon spread throughout the state. A biological control program directed against the psyllid was initiated and Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) was imported from Australia and released in California. During quarantine screening, the taxonomic status of Psyllaephagus quadricyclus Riek was assessed by one of us (RLZ) and is proposed here as a new junior synonym for P. bliteus. The experiments discussed herein provide basic biological information on P. bliteus to supplement and improve the control program. We found that P. bliteus can oviposit into psyllid nymphs of any age but prefers third and fourth instars. Observations of host-handling behavior suggest that the large lerps of fifth instar psyllids increase host-handling time, thereby impeding oviposition and providing some protection from parasitism. Female P. bliteus were observed host-feeding on all psyllid nymphal development stages. Adults are relatively long-lived and, at constant temperatures of 17, 21, 23, 26, and 32 °C, longevity is a negative linear function of temperature. Females lived significantly longer than males. Adult females can live for several months, provided with hosts and held under glasshouse conditions (22 (plus-minus) 3 °C), however, maximum egg deposition occurred within 22 days after adult emergence. Studies of larval development show that P. bliteus is a koinobiont and larval development is not initiated until the host reaches the late fourth or early fifth instar.