Laboratory adaptation reduces female mating resistance in the sweet potato weevil.

Selection for genetic adaptation might occur whenever an animal colony is maintained in the laboratory. The laboratory adaptation of behavior such as foraging, dispersal ability, and mating competitiveness often causes difficulties in the maintenance of biological control agents and other beneficial organisms used in procedures such as the sterile insect technique ( SIT). Sweet potato weevil, Cylas formicarius ( Summers) ( Coleoptera: Brentidae), is an important pest in sub-tropical and tropical regions. An eradication program targeting C. formicarius using SIT was initiated in Japan with weevils being mass-reared for 95 generations to obtain sufficient sterile males. The mass-reared strain of C. formicarius exhibits weaker female resistance to male mating attempts compared with the wild strain. This could affect the success of SIT programs because mating persistence of mass-reared males might be expected to decrease in response to weak female resistance. We show that high success of sperm transfer to mass-reared females was due to weak female resistance to male mating attempts. However, the mating behavior of mass-reared males did not change. In C. formicarius, the trait of male persistence to mate was not correlated with the female resistance traits. Our results suggest that mass-rearing conditions do not have negative effects on the mating ability of the sterile males of this species, and thus that the current mass-rearing procedures are suitable for production of sterile males for the weevil eradication program. [ABSTRACT FROM AUTHOR]