Effect of food on longevity of adults of Trichogramma carverae Oatman and Pinto and Trichogramma nr brassicae Bezdenko (Hymenoptera: Trichogrammatidae)
Trichogramma spp. are among the most widely used biological control agents against lepidopteran pests. Several species are known to benefit from adult foods, especially plant nectar, but no information has been available on the requirements of Trichogramma carverae Oatman and Pinto, a newly commercialised species, or Trichogramma nr brassicae Bezdenko. In a laboratory test, adults of T. carverae in vials without food eclosed from host eggs and all died within 7 days. In vials with honey, live adults were evident for 11 days. Significantly more live adults were present in vials with honey for days 3–5 after first emergence (P < 0.05). A quadratic model accounted for 28.6% of the temporal variance in data and showed that the rate of increase in numbers of wasps per vial was significantly greater in the fed treatment (P = 0.006). For T. nr brassicae, adults in the unfed vials died within 6 days of eclosing, while those in the honey-provisioned vials were living up to 13 days from eclosion. Significantly more live adults were present in vials with honey for days 4–7 from first emergence (P < 0.05). The model that accounted for the most variation was a spline model with four knot points, accounting for 42.6% of variation, however, there was no significant effect of food treatment on the rate of increase in wasp numbers in this model. Results are discussed in relation to the use of habitat manipulation to enhance parasitoid effectiveness in biological control.