The unfulfilled promises of scorpion insectotoxins

Abstract

Since the description and biochemical characterization of the first insect-specific neurotoxins from scorpion venoms, almost all contributions have highlighted their potential application as leads for the development of potent bioinsecticides. Their practical use, however, has been hindered by different factors, some of which are intrinsically related to the toxins and other external determinants. Recent developments in the understanding of the action mechanisms of the scorpion insectotoxins and their bioactive surfaces, coupled with the exploration of novel bioinsecticide delivery systems have renewed the expectations that the scorpion insectotoxins could find their way into commercial applications in agriculture, as part of integrated pest control strategies. Herein, we review the current arsenal of available scorpion neurotoxins with a degree of specificity for insects, the progress made with alternative delivery methods, and the drawbacks that still preclude their practical use.

Engineered action at a distance: Blood-meal-inducible paralysis in Aedes aegypti

“…Widespread use against adult mosquitoes of insecticides that target voltage-gated sodium channels (VGSC) [26] at neuromuscular junctions indicated that this could be an appropriate target for an effector at this life-stage. We designed a synthetic, neurotoxic effector construct consisting of a fusion between the invertebrate-specific, VGSC-targeting, scorpion-toxin gene AaHIT from Androctonus australis hector [27, 28] and the secretory signal peptide from Autographa californica baculovirus major envelope glycoprotein (gp67) [29], under the transcriptional control of tetO. Our hypothesis was that, when combined with the VgA1-tTAV line, this construct would allow blood-meal inducible, fat-body specific expression of AaHIT, which would be secreted into the haemolymph after translation; a common feature of fat-body expressed proteins such as VitellogeninA1 [30], where it would circulate, eventually being made available to VGSCs at neuromuscular junctions.…”

Orally Delivered Scorpion Antimicrobial Peptides Exhibit Activity against Pea Aphid (Acyrthosiphon pisum) and Its Bacterial Symbionts

“…These AMPs showed insecticidal activity at different concentrations and they clearly affected aphid survival and reproduction, but also significantly reduced the population size of both B. aphidicola and S. symbiotica . There is a growing interest in the development of bio-insecticides derived from the venom of arachnids that prey on insects [ 53 , 54 , 55 , 56 ]. The natural characteristics of scorpion AMPs make them attractive candidates for this purpose because they are short and linear, and therefore easy to synthesize at low costs.…”

Toxicity and Deleterious Impacts of the Deathstalker Scorpion, Leiurus quinquestriatus, Venom on Development of the Greater Wax Moth, Galleria mellonella (Lepidoptera: Pyralidae)

“…The inhibited growth of G. mellonella, in the current study, might be a result of the blocked release of certain peptides, causing an alteration in the ecdysteroid and juvenoid titers (Barnby and Klocke, 1990), since the scorpion L. quinquestriatus venom contains different biologically active compounds similar to polypeptide neurotoxin (Tan et al, 2006;Ortiz and Possani, 2015). Two types of venoms were identified in L. quinquestriatus venom (Lqh7) and (lqh6) (Hamon et al, 2002).…”