This is the first study to show evidence for systemic RNAi in A. tumida in response to injected dsRNA, but further research is required to develop methods to induce RNAi effects via ingestion. © 2016 Crown copyright. Pest Management Science © 2016 Society of Chemical Industry.

Although fungi are used to control a variety of insect pests, it is accepted that their usage could be increased if their efficacy was greater. The outcome of the interaction of a fungus and a pest insect may be influenced by a number of criteria, including the ability of the insect to mount effective immune responses against the pathogen. In view of this, we aimed to determine if a recombinant immunosuppressive wasp venom protein (rVPr1) can increase the susceptibility of larvae of the lepidopteran pest, Mamestra brassicae, to the fungal biological control agent, Beauveria bassiana. Bioassays indicated that when larvae were injected with 3.5 µl of rVPr1 and 100 B. bassiana conidia (combined injection assays), a significant reduction in survival of larvae occurred compared with each treatment on its own (P=0.006). Similar results were obtained when larvae were dipped in a solution containing 3 × 10(6) B. bassiana conidia per ml and then injected with 3.5 µl of rVPr1 2 days later (topical application assays), (P<0.001). These results indicate that rVPr1 can increase the efficacy of B. bassiana toward a lepidopteran pest, and are discussed within the context of insect immune responses and integrated pest management.

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The parasitic small hive beetle (Aethina tumida) feeds on pollen, honey and brood of the European honey bee (Apis mellifera); establishment in North America and Australia has resulted in severe economic damage to the apiculture industry. We report potential for the "in-hive" use of a novel biopesticide that is toxic to this invasive beetle pest but harmless to honeybees. Constructs encoding the spider venom neurotoxin ω-hexatoxin-Hv1a (Hv1a) linked to the Nor C-terminus of snowdrop lectin (GNA) were used to produce recombinant Hv1a/GNA and GNA/Hv1a fusion proteins. Both were similarly toxic to beetles by injection (respective LD 50 s 1.5 and 0.9 nmoles/g larvae), whereas no effects on adult honeybee survival were observed at injection doses of > 200 nmoles/g insect. When fed to A. tumida larvae, GNA/Hv1a was significantly more effective than Hv1a/GNA (LC 50 s of 0.52 and 1.14 mg/ml diet, respectively), whereas both proteins were similarly toxic to adults. Results suggested that the reduced efficacy of Hv1a/GNA against larvae was attributable to differences in the susceptibility of the fusion proteins to cleavage by gut serine proteases. In laboratory assays, A. tumida larval survival was significantly reduced when brood, inoculated with eggs, was treated with GNA/Hv1a. Keywords Small hive beetle (Aethina tumida) • European honeybee (Apis mellifera) • Fusion proteins • ω-hexatoxin-Hv1a • Snowdrop lectin (Galanthus nivalis agglutinin) Key message • The small hive beetle is a serious invasive pest of the European honeybee and represents a serious threat to apiculture. • Current chemical control methods are limited due to their inherent toxicity towards honeybees. • Here we report the potential use of a recombinant fusion protein, containing a spider venom neuropeptide linked to a plant "carrier" lectin, as an "in-hive" treatment for the control of small hive beetle larvae and adults which has no toxicity towards bees.

An alginate-based microsphere has potential to deliver the proteinaceous bioactive rVPr1 to pest insects.