The movement abilities and resource location behaviour of Tribolium castaneum: phosphine resistance and its genetic influences

Abstract

Resistance to the fumigant phosphine has been demonstrated to impact on the dispersal abilities of the stored product pest Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). A series of behavioural bioassays were conducted in a wind tunnel to further investigate whether the fitness consequences of phosphine resistance on flight propensity and resource localisation could be influenced by attractive odours or individual factors such as mating status. The movement of four T. castaneum genotypes was assessed: (1) field-derived phosphine-susceptible beetles, (2) laboratory-cultured, phosphine-susceptible beetles, (3) laboratory-cultured, phosphine-resistant beetles and (4) resistant introgressed beetles that are almost identical genetically to the laboratory-susceptible population. Odour preference was similar across all four genotypes as the commercially available T. castaneum aggregation pheromone and cotton seeds appeared to be stronger motivators for movement compared to whole wheat flour. Unmated beetles clearly responded more strongly to the aggregation pheromone lure compared to mated beetles, as mated beetles located resources less frequently and took longer to locate resources. However, no significant difference was observed in the flight response of mated and unmated beetles towards the aggregation pheromone lure. Phosphine resistance status of individual beetles affected their resource localisation abilities and their flight activity negatively. Our results demonstrated pleiotropic effects of phosphine-resistant genes on the movement behaviour of T. castaneum, and this has implications for the spread and development of phosphine resistance outside of phosphine application sites.