Interactions between evolved pesticide resistance and pesticide exposure influence immunity against pathogens

Abstract

Chemical and microbial pesticides are both important tools in combating agricultural pests and disease vectors. However, the interactive effects of chemical and microbial agents on insect physiology could result in either antagonism or facilitation among control strategies, as both can activate stress, detoxification, and immune responses. In natural populations, moreover, the evolution of resistance to chemical pesticides is common and often involves differential regulation of mechanisms involved in the primary responses to both pathogens and pesticides, adding an additional degree of complexity for predicting net control outcomes. To investigate the interactive effects of chemical pesticide resistance, exposure, and bacterial infection on host outcomes, we experimentally evolved resistance to two different classes of pesticides (organophosphates and pyrethroids) in the red flour beetle, Tribolium castaneum. We exposed pesticide susceptible and resistant lines to pesticides, the entomopathogen and biocontrol agent Bacillus thuringiensis (Bt), or both. Pesticide resistance and Bt exposure were individually associated with slower development, indicating sub-lethal fitness costs to resistance and infection, respectively. After organophosphate exposure, however, beetles developed more quickly and were more likely to survive if also exposed to Bt. We used RNAseq to examine the interactive effects of pesticide resistance, pesticide exposure, and Bt exposure on gene expression. Pyrethroid-resistant insects exhibited dampened immune responses to Bt infection relative to susceptible ones. In a similar vein, simultaneous exposure to organophosphates and Bt resulted in muted stress-associated transcriptional responses compared to exposure with only one factor. Our data suggest that evolved resistance, pesticide exposure, and biopesticide infection all exert contrasting effects on life history parameters and host physiology that could ultimately influence the demography and control of pest populations in complex ways.

Impacts of Pesticides on Oral Cavity Health and Ecosystems: A Review

“…Contact of the oral tissue with pesticides triggers an immune response and increased oxidative stress due to increased levels of reactive oxygen species (ROS). Oxidative stress damages the epithelium, alters cell function, and favors the development of caries, periodontitis, oral cancer, and a higher degree of bacterial infections [ 4 , 51 , 52 , 57 ].…”

“…Contact with pesticides has complex effects on the response of the host, and the reaction depends on the type of BI [ 57 ]. Table 3 summarizes studies that determined the effects of pesticides on the oral cavity based on the chemical classification of the pesticide.…”