Protease activity in the larval stage of the parasitoid wasp, Eulophus pennicornis (Nees) (Hymenoptera: Eulophidae); effects of protease inhibitors

Abstract

Hymenopteran, parasitoid wasps have good potential for use in integrated pest management (IPM); for example, the gregarious ectoparasitoid, Eulophus pennicornis, has been suggested as a biological control agent for larvae of the tomato moth (Lacanobia oleracea L.). However, the processes by which such parasitic larvae are able to utilize the nutritional resource provided by the host have been little studied. Protease activity was present in E. pennicornis larvae, and characterization of the enzymes responsible for proteolysis was performed using a range of synthetic substrates and specific inhibitors. Serine protease enzymes was both trypsin- and chymotrypsin-like activities were present. A range of plant-derived serine protease inhibitors was tested for activity against these enzymes. Certain inhibitors, notably soybean Kunitz inhibitor (SKTI), inhibited enzyme activity by > 80% at < 10(-5) M. When SKTI was fed to L. oleracea larvae in an artificial diet, the inhibitor was subsequently detected within the larval haemolymph, showing that protease inhibitors in the host diet can be delivered to a parasitoid via the host haemolymph. If transgenic plants expressing foreign protease inhibitors for protection against insect pests are to form a component of IPM systems, possible adverse effects, whether direct or indirect, of transgene expression on parasitoids like E. pennicornis should be considered.

Characterisation of digestive protease in the rose sawfly,Arge rosaeLinnaeus (Hymenoptera: Argidae)

“…This result showed that the serine proteinases are the major hydrolysing enzymes in the gut of A. rosae. Similar result was reported by Down et al (1999) when they worked on ectoparasitoid Eulophus pennicornis (Hymenoptera: Eulophidae) larvae and concluded that the serine proteinases are the dominant enzymes in the gut of this insect. Also, our results are in agreement with Burgess and Gatehouse (1997) in the presence of serine proteases in gut extracts of the honeybee, Apis mellifera (Hymenoptera: Apidae).…”

Effect of dietary cowpea trypsin inhibitor (CpTI) on the growth and development of the tomato mothLacanobia oleracea (Lepidoptera: Noctuidae) and on the success of the gregarious ectoparasitoidEulophus pennicornis (Hymenoptera: Eulophidae)

“…The results of this study suggest that CpTI may have an effect on E pennicornis in terms of its ability to parasitise hosts that have ingested this protein. Although CpTI causes partial inhibition of digestive proteases of wasp larvae in vitro ,43 it is unlikely that the effects reported here are due to direct toxicity. No adverse effects on the wasp were detected when hosts were fed artificial diet containing the inhibitor as opposed to transgenic leaves.…”

Gene Pyramiding of Peptidase Inhibitors Enhances Plant Resistance to the Spider Mite Tetranychus urticae

“…In contrast, the presence of highly expressed S1 serine peptidase genes in embryo and larvae suggest that they may have other putative roles, probably associated with the regulation of growth and development. These physiological processes can potentially be targeted if the protease inhibitors may get access through the mite gut to endogenous targets, as have been already reported in insects [30], [31].…”