Effects of rearing host species on the host-feeding capacity and parasitism of the whitefly parasitoid Encarsia formosa.

Peng Dai,Linzhou Liu,Fanghao Wan,Liansheng Zang,Changchun Ruan,Michael Strand

doi:10.1093/jis/14.1.118

Abstract

Parasitoids of the Encarsia genus (Hymenoptera: Aphelinidae) are important biological control agents against whiteflies. Some of the species in this genus not only parasitize their hosts, but also kill them through host feeding. The whitefly parasitoid, Encarsia formosa Gahan, was examined to determine whether the rearing host species affects its subsequent host-feeding capacity and parasitism. E. formosa wasps were reared on Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) and Bemisia tabaci (Gennadius) ‘Q’, and their subsequent host-feeding capacity and parasitism of T. vaporariorum and B. tabaci were examined. E. formosa reared on T. vaporariorum were significantly larger in body size than those reared on B. tabaci , but these wasps killed a similar number of whitefly nymphs by host feeding when they attacked the same host species on which they were reared. Regardless of the species on which it was reared, E. formosa fed significantly more on the B. tabaci nymphs than on the T. vaporariorum nymphs. The number of whitefly nymphs parasitized by E. formosa differed between the wasps reared on T. vaporariorum and those reared on B. tabaci depending on which whitefly species was offered as a host. In addition, the wasps reared on T. vaporariorum parasitized significantly more on T. vaporariorum than those reared on B. tabaci . The wasps reared on B. tabaci , however, parasitized similar numbers of whiteflies of both host species. The results indicated that the host-feeding capacity of E. formosa was affected more by the host species attacked than by the rearing host species, but the parasitism was affected by the host species attacked and the rearing host species. Generally, E. formosa reared on T. vaporariorum killed more T. vaporariorum nymphs by parasitism and host feeding than those reared on B. tabaci. Additionally, a similar number of B. tabaci nymphs were killed by parasitism and host feeding regardless of the rearing host species. Currently coexistence of B. tabaci and T. vaporariorum on vegetable crops usually occurs in some areas; our results may provide helpful information on using mass-reared parasitoids against mixed whitefly infestations in biological control programs.

Highlights

Some species of insect parasitoids, species of the order Hymenoptera, parasitize or deposit their eggs in their hosts and feed on the hosts, which often results in host mortality (Jervis and Kidd 1986, Heimpel and Collier 1996)
E. formosa reared on T. vaporariorum killed more T. vaporariorum nymphs by parasitism and host feeding than those reared on B. tabaci
There was no difference in the number of whitefly nymphs killed by host feeding between the E. formosa reared on T. vaporariorum and those reared on B. tabaci whether T. vaporariorum or B. tabaci were offered as hosts (Fig. 2)

Summary

Introduction

Some species of insect parasitoids, species of the order Hymenoptera, parasitize or deposit their eggs in their hosts and feed on the hosts (host feeding), which often results in host mortality (Jervis and Kidd 1986, Heimpel and Collier 1996). Encarsia formosa Gahan (Hymenoptera: Aphelinidae), one of the most successfully commercialised natural enemies used for the biological control of insect pests, has been used to control the whiteflies Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) and Bemisia tabaci (Gennadius) in many countries throughout the world (Hoddle et al 1998). This parasitoid is a typical non-concurrent destructive host feeder that uses different host individuals for oviposition and host feeding (Van Roermund and Van Lenteren 1997, Zang and Liu 2008).

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Results

Conclusion