Sickly Sweet: Insecticidal Polyols Induce Lethal Regurgitation in Dipteran Pests.

Francisco Díaz-Fleischer,José Arredondo,Trevor Williams,Rodrigo Lasa,Carlos Bonilla,Diana Debernardi,Diana Pérez-Staples

doi:10.3390/insects10020053

Abstract

Polyols are commonly used in food and medicines as sweeteners and preservatives but may also have insecticidal properties against some species of Diptera. Here we compared the insecticidal activity and feeding response of glycerol and propylene glycol (PG) on two tephritids: Anastrepha ludens and Anastrepha obliqua, and the drosophilid Drosophila suzukii. First, flies were exposed to solutions of 50% sucrose and the two polyols at concentrations of 1.67 M, 2.78 M and 4.18 M for 24 h and then observed at 24 h intervals for a period of three days. Both polyols elicited strong regurgitation behavior in the three flies and killed them. Regurgitation apparently also reduced flies’ body weight, and this was particularly apparent in insects that fed on 4.18 M PG solutions. A high percentage of individuals exposed to PG solutions perished after 72 h. The number of proboscis extensions, which is associated with feeding preference, was lower in the 4.18 M polyols + sucrose mixtures than in the 50% sucrose solution. Glycerol had a lower insecticidal effect in Anastrepha spp. and very little insecticidal effect in D. suzukii. Finally, elevated regurgitation and mortality was confirmed in A. ludens treated with 1.0–2.78 M of erythritol plus sucrose. Our results demonstrate that PG, and to a lower extent glycerol, have the potential for being used as a safer method of insect pest control. The hyper-regurgitation response may contribute to the insecticidal properties of these polyols in Diptera.

Highlights

Many species of Diptera are pests of agriculture and human and animal health through direct damage to products or individuals, or as vectors of parasites and pathogens
Adult dipterans that feed on liquid meals often exhibit regurgitation, the function of which is to reduce the amount of water in food and thereby increase the nutritional value of each meal, and to lower body temperature [7,9]
No mortality was observed in control flies during the post-treatment period and only a low prevalence of mortality occurred in the glycerol treatment (Figure 4B), whereas 100% of the propylene glycol (PG)-treated flies died within the three-day post-treatment period (χ2 = 382.8, d.f. =2, p

Summary

Introduction

Many species of Diptera are pests of agriculture and human and animal health through direct damage to products or individuals, or as vectors of parasites and pathogens. These insects are usually controlled using broad-spectrum chemical insecticides. The insect crop has been considered as a potential target for novel methods of pest control [7]. This organ comprises a muscular system of pumps and sphincters located in the initial section of the digestive system, where food storage and regurgitation are regulated [8]. Adult dipterans that feed on liquid meals often exhibit regurgitation, the function of which is to reduce the amount of water in food and thereby increase the nutritional value of each meal, and to lower body temperature [7,9]

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Discussion

Conclusion