TYPES OF PARASITOID - INDUCED MORTALITY, HOST STAGE PREFERENCES, AND SEX-RATIOS EXHIBITED BY PNIGALIO-FLAVIPES (HYMENOPTERA, EULOPHIDAE) USING PHYLLONORYCTER-ELMAELLA (LEPIDOPTERA, GRACILLARIIDAE) AS A HOST

The different types of parasitoid-induced mortality, host stage preferences, and sex ratio exhibited by Pnigalio flavipes (Ashmead) to its host, Phyllonorycter elmaella Doganlar & Mutuura, was investigated in commercial apple orchards in central Washington. The parasitoid-induced mortality of Phyllonorycter elmaella consisted on average of 57.2% host stinging with oviposition, 32.7% host feeding, and 10.1% host stinging without oviposition. Pnigalio flavipes laid eggs on Phyllonorycter elmaella tissue feeders (fourth and fifth instars) an average of 5.4 times more than it did on sap feeders (first-third instars), but host-fed on sap feeders an average of 12.1 times more than on tissue feeders. When healthy tissue feeders became scarce late in the season, Pnigalio flavipes began to lay eggs on previously attacked tissue feeders (superparasitize) and then switched to laying eggs on sap feeders. The sex ratio (M:F) of Pnigalio flavipes reared from tissue feeders was almost 1 to 1. Only male Pnigalio flavipes were reared from sap feeders. © 1990 Entomological Society of America.