Selecting aggressiveness to improve biological control agents efficiency

In agroecosystems, omnivorous predators are recognized as potential biological control agents because of the numerous species pest species they prey on. Nonetheless, it could be possible to enhance their efficiency through artificial selection on traits of economical or ecological relevance. Aggressiveness is expected to be related to zoophagy, diet preferences and to a higher attack rate. The study aimed to assess the aggressiveness degree of the damsel bug, Nabis americoferus , and estimate its heritability. We hypothesized that a high aggressiveness degree can be selected, and that males are more aggressive than females. Using artificial selection, we reared two separate populations, each composed of nine genetically isolated lines characterized by their different aggressiveness degree (aggressive, docile and non-selected). After five generations, we had efficiently selected aggressive behavior. The realized heritability was 0.16 (± 0.04 S.E.) and 0.27 (± 0.1 S.E.) for aggressiveness and docility in the first population. It was 0.25 (± 0.03) and 0.23 (± 0.08 S.E.) for the second population. Males were more aggressive than females only for the second population. The potential of these individuals as biological control agents and the ecological consequences of aggressiveness is discussed.