Influence of Feeding Treatment, Host Density, Temperature, and Cool Storage on Attack Rates ofTachinaephagus zealandicus(Hymenoptera: Encyrtidae)

Abstract

Tachinaephagus zealandicus As hmead isa gregariousendoparas itoid that attacksthird instars of muscoid sies, including house sies, Musca domestica L. A colony of thisparas itoid was established from samples collected from a poultry farm in Santa Cruz da Conceicao, Sao Paulo, Brazil. The objective of this study was to evaluate the insuence of feeding treatment, host density and temperature on attack rateson T. zealandicus. Paras itoidsthat were given honey asadultsattacked two to three times as many house sy larvae (25 host attacks/female/d) as parasitoids that were given only water or nothing. Host attacks and progeny production by T. zealandicus on house sy and Chrysomyia putoria increased over the range of host:parasitoid ratios tested, reaching a maximum of 21Ð22 hosts killed and 13 progeny produced/female/d at the highest host density of 32 larvae/female. Host attacks were higher at 22C than at the other temperaturesstudied (20 Ð29 C), but differences in attack rateswere small over the range of 20 Ð27 C (10 Ð13 host attacks/female). Comparatively few hosts (6.3) were attacked at 29C. Higher rates of progeny production also were observed among parasitoids tested at lower temperatures (9 Ð11 progeny produced/female at 20 Ð22C) than at 29C (1.8 progeny/female). Femalesof T. zealandicus that were stored at 15C after emergence had highest rates of host attacks (58 Ð 62 hosts killed per group of Þve female parasitoids) and progeny production (174 Ð261 progeny) after 6 Ð12 d of storage at this temperature; relatively few hosts were attacked or parasitized (6 Ð9 host attacks and progeny/group) after 0 o r1da t 15C.