Demonstrating the potential of a novel spider venom-based biopesticide for target-specific control of the small hive beetle, a serious pest of the European honeybee

Abstract

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.

Enhancing the oral and topical insecticidal efficacy of a commercialized spider venom peptide biopesticide via fusion to the carrier snowdrop lectin (Galanthus nivalis agglutinin)

“…When injected into M. brassicae larvae dose‐dependent mortality predominantly occurred 24–72 h postinjection, and similar respective LD 50 values of 16.29 and 13.70 nmoles g −1 for HxTx‐Hv1h and HxTx‐Hv1h/GNA were derived. These values are comparable to injection LD 50 values of 18 nmol g −1 M. brassicae larvae reported previously for both Hv1a and Hv1a/GNA 22 . This contrasts with previous reports showing much higher potency of HxTx‐Hv1h (LD 50 38 pmol g −1 ) as compared to Hv1a (LD 50 87 pmol g −1 ) when injected into houseflies 10,11 .…”

“…These values are comparable to injection LD 50 values of 18 nmol g −1 M. brassicae larvae reported previously for both Hv1a and Hv1a/GNA. 22 This contrasts with previous reports showing much higher potency of HxTx-Hv1h (LD 50 38 pmol g −1 ) as compared to Hv1a (LD 50 87 pmol g −1 ) when injected into houseflies. 10,11 However, a cautionary approach should be taken when comparing efficacy across different insect species that show large variability in levels of susceptibility to venom-derived neurotoxins.…”

“…Neurotoxic peptides must access the CNS or peripheral nervous system (PNS) to reach their target site(s) of action, and failure of ingested peptides to cross the gut epithelium is thought to be the major barrier to achieving oral efficacy. We have demonstrated previously that fusion of several different venom neurotoxins, including ω‐hexatoxin‐Hv1a, to the snowdrop lectin Galanthus nivalis agglutinin (GNA) carrier protein dramatically enhances oral insecticidal activity 17–22 . GNA is able to transport attached peptides across the insect gut allowing delivery to the circulatory system.…”

Chromosomal‐level genome of a sheet‐web spider provides insight into the composition and evolution of venom

“…The evolutionary success of spiders is largely due to the evolution of pharmacologically complex venom that guarantees rapid immobilization for predation and defence (King & Hardy, 2013). The complex mixtures of diverse and selective natural products found in venom have garnered increased interest as potential therapeutics and biopesticide development (Benfatti, 2019; Laxme et al, 2018; Powell et al, 2019; Rodrigues et al, 2021).…”

Seasonal Changes in Size and Mite-Prevalence of a Bee Colony Exposed to Dinotefuran via Pollen Paste and Damaged by <em>Varroa</em> Mites

“…Then, there have been reports on Varroa-mite-damage prevention measures [21][22][23][24][25][26][27]. The damage situation of bee colonies by pests other than the Varroa mite was investigated and countermeasures against those pests such as the small hive beetle [28][29][30][31][32][33][34] and the wax moth larva [35][36][37][38][39][40] were reported.…”