Transmission of Metarhizium brunneum conidia between male and female Anoplophora glabripennis adults

Transmission of conidia between mates of the Asian longhorned beetle, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), was studied using two isolates of the entomopathogenic fungus Metarhizium brunneum Petch (Hypocreales: Clavicipitaceae) (formerly M. anisopliae). After one beetle was inoculated and caged with a mate for 6 h, conidia were rinsed off each beetle using Tween-80 and pentane to count conidia transferred. Treated males transmitted more conidia to females than treated females transferred to males. Untreated partners did not die as quickly as their inoculated mates, but died significantly faster than controls. For beetles inoculated with ARSEF 7711, the difference in time to death between inoculated beetles and their untreated mates was shorter when males were inoculated than when females were inoculated. We hypothesize that greater conidial transmission from males to females was due to their relative positions during copulation and the prolonged post-copulatory mate-guarding characteristic of males.