Morphological and Physiological Characteristics that Contribute to Insecticide Resistance in Bed Bug (Cimex lectularius L.) Eggs


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Virginia Tech


Although bed bug eggs are a difficult life stage to control with our currently labeled insecticides, few studies have examined how bed bug egg morphology and physiology is potentially related to pesticide resistance in bed bug eggs. Bed bug egg morphological features were examined using scanning electron microscopy (SEM) and the chorion and respiration structures were identified. Scanning electron microscopy photographs and bed bug egg measurements indicated there were no morphological differences between different bed bug egg strains (susceptible and resistant). Bed bug egg respiration rates measured by the amount of oxygen consumed (standard metabolic rate; SMR) also indicated there was no difference in SMR between different bed bug egg strains. Water conservation during respiration is vital to terrestrial insects. Therefore, similar patterns would be expected between egg water loss and respiration rates. However, susceptible strain eggs lost more water than one resistant strain of bed bug eggs, which was dissimilar from the respiration results, indicating that bed bug egg water loss and respiration are not directly related. Dose- response bioassays using two insecticide formulations (Temprid; imidacloprid/β-cyfluthrin, and Transport; acetamiprid/bifenthrin) indicated that bed bug eggs collected from pyrethroid resistant adult bed bug strains are also highly resistant. RNA sequencing of bed bug eggs from two resistant strains indicated that egg resistance may be directly related to the overexpression of multiple genes associated with insecticide resistance.



Cimex lectularius L., Bed Bug Eggs, Scanning Electron Microscopy, Respirometry, Insecticide Resistance, RNA-Seq