Male hypofertility induced by Paraquat consumption in the non-target parasitoid Anisopteromalus calandrae (Hymenoptera: Pteromalidae)

The effects of a herbicide - Paraquat - on male development and reproduction were tested on the parasitoid wasp Anisopteromalus calandrae (Hymenoptera, Pteromalidae) by injecting host larvae with different concentrations of this substance. Data measured were: (1) developmental success, (2) sperm stock in seminal vesicles, (3) ability to copulate and transfer sperm, and (4) offspring production. Both developmental success and sperm in seminal vesicles were reduced in the “Paraquat” groups. However, neither sperm stored in the females' spermatheca, nor offspring production (number of female offspring and sex ratio) differed from controls, whatever the host treatment. The decreased of male sperm reserve in ''Paraquat” group is likely to reduce their reproductive success because they can succefully inseminated less female than control males. These males are thus hyporfertiles. Because Paraquat has non-negligible consequences on non-target parasitoid males, it is likely to affect natural and controlled insect populations.