Host instar suitability in two invasive whiteflies for the naturally occurring parasitoid Eretmocerus hayati in China

Abstract

Knowledge about host instar suitability of a parasitoid is critical to ensure bio-control efficacy. Studies were conducted to assess parasitizing and feeding behavior of a naturally occurring parasitoid, Eretmocerus hayati, on different instar nymphs of two invasive whiteflies, Bemisia tabaci (Gennadius) cryptic species MEAM1 and MED, in China. Er. hayati parasitized and fed on all nymphal stages of the two whiteflies, but preferred to parasitize 1st, 2nd and 3rd instar hosts of B. tabaci MEAM1 and 2nd instar hosts of B. tabaci MED. Parasitoids preferred to feed on earlier instar hosts of the two species. The preimaginal development times of parasitoids were the longest on 1st instar hosts, intermediate on 2nd and 3rd instars, and the shortest on 4th instars. The immature development time on B. tabaci MED hosts were slightly shorter than on MEAM1 ones. The highest parasitoid survivorships were on 4th instars, and the lowest were on 1st instars in both host species. The sex ratios of offspring remained stable at 0.5. Er. hayati could be a more suitable biological control agent for B. tabaci MED. Our results could provide guidance for indoor mass-rearing of Eretmocerus spp. for inundative release in the field, accelerating IPM programs against B. tabaci in China.