Understanding Bed Bug (Cimex lectularius (L.)) Egg Susceptibility to Different Insecticide Treatments

Abstract

Bed bug (Cimex lectularius L.) eggs are the most difficult life stage to eradicate and are often the reason that pest management professionals must apply multiple treatments over time in an infested home. This dissertation was aimed at developing a better understanding of how we might improve bed bug egg eradication in the field. For the first study, daily changes in egg respiratory rates of susceptible and resistant bed bug strains were measured and compared between untreated eggs, and eggs treated with either an insecticide or a dish soap. The results of this study indicated that there were significant differences in respiratory rates as the eggs developed, but there were no significant differences between susceptible and resistant strains. Interestingly, it was found that the dish soap significantly reduced embryonic respiration and hatch compared to the two insecticide products. In the second study, eggs from the resistant and susceptible strains were grouped into two developmental stages (pre-blastokinesis or post-blastokinesis) and then treated with multiple aerosol insecticide products, a biopesticide product (Beauveria bassiana, GHA), and the previously tested household dish soap. In a follow-up study, first instar bed bugs were exposed to insecticide or soap-treated surfaces (dried for 24 hours) for two weeks to assess the insecticide's residual efficacy. The results of these insecticide bioassays indicated that younger eggs were slightly more susceptible than older eggs to the insecticide and soap treatments. Bedlam Plus® and Temprid® Ready-to-Spray had a greater impact on younger eggs when compared to older eggs. The Crossfire® aerosol and Aprehend® products were not as effective at treating eggs, but their residual efficacy produced high first instar mortality. Interestingly, the household dish soap treatments led to over 89% egg mortality, and over 90% first instar mortality during the constant exposure assays. The third project was a field study (2022-2024) that evaluated the efficacy and labor time of an assessment-based pest management (APM) program. The APM program consisted of vacuuming and treatment with a bed bug labelled biopesticide (Aprehend®) to address bed bug infestations in different residences. These evaluations were conducted for 90 days, in residences that had been designated with either high, medium, or low-level infestations. Each housing space was treated every 30 days throughout the three-month study. Overall, the mean bed bug populations were reduced by at least 93% after 90 days. Additionally, the labor significantly decreased over time. The fourth study (2021-2024) was an evaluation of the efficacy and labor hours of structural fumigation (sulfuryl fluoride) using two different structural sealing methodologies (tape-and-seal and tarping). While it was found that fumigation was an excellent method for eliminating bed bug eggs, the sealing of the home had to be conducted correctly to reduce leakage. Although the tarping method was significantly more labor intensive than tape-and-seal, there were no significant differences between the total cost (labor and gas usage) of either method tested. Additionally, due to excessive leaking, two out of the five tape-and-sealed homes had some sentinel bed bug eggs hatch and survive (10%), because those two homes did not reach the lethal dosage rate.