Blood deprivation and heat stress increase mortality in bed bugs (Cimex lectularius) exposed to insect pathogenic fungi or desiccant dust

Abstract

Bed bugs (Cimex lectularius L.) have returned as a nuisance pest in the last 20 years. Different bed bug control measures in combination have not been thoroughly studied, although induction of multiple stressors may improve extermination. The effects of heat stress only, heat stress followed by exposure to insect pathogenic fungi, and heat stress followed by exposure to desiccant dust on starved and blood‐fed bed bugs were investigated. Five days at 22 °C (control), 32 °C, 34 °C, or 36 °C (heat stress) did not cause mortality in adults. However, their starved first instar nymphs produced after heat stress suffered mortalities of 33%, 56% and 100%, respectively. Exposure to insect pathogenic fungi after heat stress increased the mortality of adults and their progeny compared to exposure to fungi without heat stress. The beneficial effects of heat stress were not observed in blood‐fed bed bugs. Desiccant dust killed all nymphs within 2 days and all adults within 3 days regardless of previous heat stress, but survival time was prolonged by access to blood. This study highlights the advantage of combining different methods in pest management, and points to heat stress combined with blood deprivation as possible management elements to increase the control success.

Cuticular protein genes involve heat acclimation of insect larvae under global warming

“…Temperature beyond the threshold for growth and development will cause physiological abnormality and even death of insects. Heat stress increases mortality of bed bugs Cimex lectularius exposed to pathogenic fungi Beauveria bassiana or desiccant dust (Rukke et al, 2021) and reduces egg‐to‐adult survive of Drosophila suzukii (Green et al, 2019). Facing the global warming, insects have evolved a series of strategies to response to heat stress in physiology and behaviour (Ma et al, 2021).…”

Can behaviour and physiology mitigate effects of warming on ectotherms? A test in urban ants

“…What, then, are the consequences of foraging at temperatures that are hotter than preferred, but safely below lethal limits? Sublethal heat stress in adult arthropods can reduce fecundity and longevity and increase later susceptibility to other stressors such as disease (Colinet et al, 2015; Rukke et al, 2021). Even incremental warming at overtly non‐stressful temperatures increases ectotherm metabolism and decreases insect longevity (Promislow et al, 2022).…”

“…What, then, are the consequences of foraging at temperatures that are hotter than preferred, but safely below lethal limits? Sublethal heat stress in adult arthropods can reduce fecundity and longevity and increase later susceptibility to other stressors such as disease (Colinet et al, 2015;Rukke et al, 2021) d The last two columns provide interpretation of the logistic coefficients. Although the response of interest is probability of occupancy, logistic models do not represent a fixed change in probability of occupancy per °C.…”

Biological control of Cimex lectularius with Beauveria bassiana: Effects of substrate, dosage, application strategy, and bed bug physiology

“…The conidia are expected to remain viable for several weeks indoors, but bed bug aggregation chemicals may negatively influence the conidial functionality 15–18 . Temperature stress due to increased ambient temperatures may increase the effect of insect pathogenic fungi on bed bugs, and ticks have shown variation in mortality associated with feeding status or developmental stage 19–21 . Environmental factors are distinct determinants of the effect of insect pathogenic fungi outdoors 4,17 .…”