Sub-Lethal Effects of Pirimiphos-Methyl Are Expressed to Different Levels in Wings of Three Stored-Product Coleopterans: A Geometric Morphometrics Investigation

Abstract

Tenebrio molitor L. (Coleoptera: Tenebrionidae), Prostephanus truncatus (Horn), and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) are noxious insect pests of grains in storages. Pirimiphos-methyl is widely used to protect grains at the post-harvest stage. However, the sub-lethal impact of this active ingredient on the offspring of all three coleopterans remains unknown. Thus, mated females of each species were exposed separately to pirimiphos-methyl at short exposures (30 min, 3, 5, 8, 16, 24, and 36 h), where the elytra and hindwings of the adult progeny were analyzed with the geometric morphometrics method. Males and females of all species were incorporated into the analysis. The results revealed variability among species. Tenebrio molitor was the most sensitive among three species, displaying significant deformations in the elytra and hindwings. Males had more conspicuous morphological changes than females. Prostephanus truncatus hindwings exhibited deformities after 36 h of exposure to pirimiphos-methyl. In contrast, R. dominica offspring were not affected by pirimiphos-methyl. In light of our findings, organophosphorus insecticides may cause variable sub-lethal effects to stored-product insects. This issue may lead to different insecticidal treatments according to the targeted stored-product species.

Being exposed to low concentrations of pirimiphos‐methyl and chlorfenapyr has detrimental effects on the mobility of Trogoderma granarium

“…The findings agreed with results of our study about sensitivity of T. granarium females to pirimiphos‐methyl. Nevertheless, a recent study showed inverse results where males of Tenebrio molitor L. (Coleoptera: Tenebrionidae) derived from females treated with pirimiphos‐methyl at sublethal exposures were more sensitive than females 30 . Therefore, the response of sexes of coleopterans to an insecticide is likely to be species‐dependent rather than a general trend.…”

“…Apart from the lethal effects of insecticides on storage pests, they exhibit sublethal effects that can negatively affect several biological and behavioral traits of insects 27–30 . Sublethal effects of insecticides are related to aggressive behavior, courtship, fecundity, longevity, sex ratio, mobility, lifespan, fertility, and morphology, among others 30–35 . For instance, successful copulations of Sitophilus oryzae (L.) (Coleoptera: Curculionidae) were reduced after exposure of both sexes to sublethal doses of pyrethrins 36 .…”

Sublethal Effects of Chlorantraniliprole on the Mobility Patterns of Sitophilus spp.: Implications for Pest Management

“…Besides inducing mortality in storage pests, synthetic pesticides also induce sublethal effects that can influence the biology and behavioral characteristics of insects [ 18 , 19 ]. Some of the sublethal effects include aggressive behavior and a negative impact on courtship, lifespan, fecundity, fertility, locomotion, and morphology [ 20 , 21 , 22 ]. Insects have developed a range of behavioral reactions to insecticidal substances, leading to their reduced efficacy [ 23 ].…”