Potential of diaphania hyalinata and tenebrio molitor as alternative host for mass rearing of palmistichus elaeisis (Hymenoptera: Eulophidae)

Abstract

Palmistichus elaeisis Delvare & LaSalle (Hymenoptera: Eulophidae) is a polyphagous endoparasitoid wasp, a natural enemy of agricultural and forest pests. Alternative hosts can reduce the mass rearing costs of such natural enemies. The objective of this study was to test the suitability of Diaphania hyalinata Linnaeus (Lepidoptera: Crambidae) and Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae) as alternative hosts for mass rearing of P. elaeisis under laboratory conditions. Diaphania hyalinata and T. molitor pupae were exposed to females of P. elaeisis. Palmistichus elaeisis parasitized 99% of the pupae of both hosts with 60% of adult emergence. The parasitoid’s development period was shorter with D. hyalinata. Offspring size, sex ratio, and longevity were similar in both hosts. Specimens of P. elaeisis emerged from T. molitor were larger than those emerged from D. hyalinata. The reproductive apparatus of P. elaeisis female was fully formed and functional by the early hours of adulthood, with a pair of ovaries, a pair of accessory glands, lateral oviducts, and spermatheca. The ovarioles were of the meroistic polytrophic type. Egg maturation in adults which emerged from T. molitor was faster than in those from D. hyalinata, probably due to the quality and quantity of the hosts as nutritional sources for the parasitoid. The reproductive success, high parasitism rate, complete development and greater proportion of P. elaeisis females in their offspring confirm the quality of both T. molitor and D. hyalinata as hosts for mass rearing of this natural pest enemy.