The Effect of Time Postexposure and Sex on the Horizontal Transmission of Metarhizium brunneum Conidia between Asian Longhorned Beetle (Coleoptera: Cerambycidae) Mates

ABSTRACT A study using Metarhizium brunneum Petch fungal bands designed to improve delivery of conidia to adult Asian longhorned beetles, Anoplophora glabripennis (Motschulsky), was conducted to determine how a time delay between exposure to infective conidia and pairing of male and female beetles would affect the ability to successfully transfer lethal doses of conidia to a mate. We measured conidial load at the time of mate pairing (0, 4, 24, 48 h postexposure) and assessed its effect on beetle mortality. Conidial load per beetle decreased across the four sampling times, and there was no effect of beetle sex on conidial load. At all time periods postexposure, beetles that climbed across fungal bands carried enough conidia that at least some of their indirectly exposed mates died of mycosis. For indirectly exposed beetles, mortality decreased significantly as the time delay increased from 0 to 48 h, and this was independent of beetle sex. Median survival time was only 11.5 d for females indirectly expose...