Mass rearing of two larval parasitoids of Helicoverpa spp. (Lepidoptera: Noctuidae): Netelia producta (Brullé) and Heteropelma scaposum (Morley) (Hymenoptera: Ichneumonidae) for field release

Abstract

Parasitoids are becoming an increasingly important part of our biological arsenal in Integrated Pest Management strategies against major insect pests like Helicoverpa armigera (Hübner). Inundative or supplementary releases of parasitoids have been successfully used in the past to help manage insect pests in the field. This paper reports attempts to mass rear two larval parasitoids of Helicoverpa spp., Heteropelma scaposum and Netelia producta . The results suggest that N. producta is the easier species to culture, although the parasitism rates for either wasp species were not high (29% for N. producta and 19% for H. scaposum ). The authors suggest ways in which the parasitism rates could be increased and culturing made easier. It was found that culturing H. scaposum resulted in a male-biased sex ratio that was less suitable for mass release. Possible reasons for the bias are discussed, including singlelocus complementary sex determination (CSD) that can result in a high proportion of homozygotic diploid males occurring in inbred populations. Although single-locus CSD is a plausible explanation for the male biased sex ratio, the authors caution that more work is needed to confirm that it can occur in H. scaposum .

The ghost sex-life of the paedogenetic beetle Micromalthus debilis

“…Often females control sex allocation directly. Most non-social haplodiploid species are parasitoids and have sex ratios ranging from highly male-biased 28 to highly female-biased 29 . In sexually reproducing diplodiploid species, sex ratio biases of intrinsic genetic origin (e.g., not due to manipulation by endosymbionts) are extremely rare 30 .…”

Biology and development of Chaetophthalmus dorsalis (Malloch) (Diptera: Tachinidae) parasitising Helicoverpa armigera (Hübner) and H. punctigera Wallengren (Lepidoptera: Noctuidae) larvae in the laboratory

“…Another parasitoid of Helicoverpa spp. larvae in Australia, the ichneumonid Netelia producta (Brullé), is known to lay its external eggs just behind the head capsule and it is thought that this done so that they could not be removed by the host's mandibles (Johns & Whitehouse 2004). The observed differences in the point of entry of planidia in H. punctigera and H. armigera larvae is difficult to explain but may again relate to differences in cuticle toughness.…”

“…Further research on the biology and ecology of C. dorsalis is warranted to investigate its potential for mass rearing and releasing to control Helicoverpa spp. Previous studies on lepidopteran parasitoids in Australia have concentrated on the amenability of mass rearing hymenopterans (Johns & Whitehouse 2004). However, this study has demonstrated that C. dorsalis is relatively easy to rear in the laboratory and may be amenable to mass rearing for field release using similar methods developed by Gross (1994) for A. marmoratus whereby planidia were mechanically extracted from fecund females and applied as an aqueous suspension onto crops.…”

“…1986). The egg, larval and pupal stages are parasitised by at least 45 species of Hymenoptera and Diptera (Johns & Whitehouse 2004). Seventeen genera of Tachinidae, comprising at least 21 species, have been listed as parasitoids of Helicoverpa spp.…”

“…The potential of parasitoids to control Helicoverpa spp., both in Australia and overseas, through mass rearing and release has been the focus of several studies (e.g. King & Coleman 1989; Neil & Specht 1990; Johns & Whitehouse 2004). However, most have only considered hymenopteran wasps with tachinid flies receiving little attention (Feener & Brown 1997) despite past successes in mass rearing a tachinid parasitoid of Helicoverpa spp.…”