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Resistance to Deltamethrin in Triatoma Infestans (Hemiptera: Reduviidae): Does it Influence the Phenotype of Antennae, Wings, and Heads?

Abstract:

In vector control terms, resistance is the development of the ability, in an insect population, to tolerate doses of an insecticide that are lethal to most individuals in a normal population of the same species. The genetic changes that determine resistance may have adaptive costs in the resistant phenotype or, conversely, may result in an adaptive advantage when compared to susceptible insects in the environment without insecticides. Triatoma infestans is the main vector of Trypanosoma cruzi in the southern cone of South America. High insecticide resistance in T. infestans was detected in Argentina in Salta and Chaco provinces. The objective of this study was to determine the possible morphometric changes in wings, heads and in the antennal phenotype of deltamethrin-resistant T. infestans (RR) males and females compared to susceptible insects (SS), evaluating its implication in adaptive processes such as olfactory capacity, dispersion, and probability of colonizing new habitats, among others. Nine type I landmarks were marked on wings, 5 type II landmarks on heads and 10 antennal sensilla were counted on 94 individuals of both sexes (resistant and susceptible from first and second laboratory generations). Morphological divergence was observed between the two groups with different toxicological status. The RR insects showed smaller sizes of wings, heads and shapes compatible with lower dispersal potential and different active dispersal strategies. The antennae follow these changes, although more marked in females. This study characterizes for the first time T. infestans RR and SS through wings, heads and antennae. The results …