Comparative assessment of host selection behavior of Trichogramma species under no-choice and dual-choice conditions

Abstract

Trichogramma chilonis Ishii (Hymenoptera: Trichogrammatidae), which is typically raised on Corcyra cephalonica eggs, is used extensively in the biological control of lepidopteran pests. However, research into alternate hosts like the Eri silkworm, or Philosamia ricini, may be beneficial for integrating with current agro-silkworm systems and achieving sustainable mass production. Utilising eggs from C. cephalonica and P. ricini over five consecutive generations, this study assessed the host selection behaviour and biological performance of T. chilonis under no-choice and dual-choice conditions. Whereas dual-choice tests replicated field conditions by simultaneously exposing parasitoids to both hosts, no-choice tests evaluated host suitability by exposing them to only one host type per replicate. The percentage of parasitisation, adult emergence per egg, female progeny percentage, and adult longevity were among the biological parameters that were assessed. The findings showed that although the first generations preferred C. cephalonica, T. chilonis performance was greatly enhanced by repeated exposure to P. ricini in every parameter, suggesting behavioural adaptation and physiological compatibility. Eri eggs may make an excellent long-term host due to their improved reproductive characteristics and survivability. The use of Eri eggs has applications in sericulture that go beyond entomological considerations. The production of eri eggs will provide farmers with value addition and a source of income diversification. Their use in Trichogramma mass rearing offers a low-cost, high-return model that supports rural livelihoods and pest management. The study emphasises that P. ricini eggs are a viable, environmentally friendly substitute host for large-scale T. chilonis rearing, encouraging cooperation between biological control and sericulture efforts.