Lure-and-infect and lure-and-kill devices based on Metarhizium brunneum for spotted wing Drosophila control

In the current study, we have designed two experimental devices to study the potential of Metarhizium brunneum (Petch) and its crude extract (filtered growth medium) for the control of Drosophila suzukii (Matsumura). An experimental autoinoculation device impregnated with conidia of EAMa 01/58-Su strain was designed for a lure-and-infect strategy. D. suzukii adult mortality resulted in a 62.2% with an average survival time of 3.6 days, with no significant differences among attractiveness to adults of red and black colours used in the devices. Nevertheless, a 48.0% mortality of untreated males was obtained after being coupled with inoculated females, whereas only 24.0% of untreated females was killed after being coupled with inoculated males, thereby revealing the horizontal transmission potential of the strain in these inoculation devices. We observed an 84.7% reduction in fecundity in M. brunneum-challenged D. suzukii females. Finally, we designed a lure-and-kill device to dispense a crude extract of the EAMb 09/01-Su strain that had previously shown acute mortality in D. suzukii, with an exposure time of 6.9 h required to achieve 50.0% mortality. Mixing the extract with feeding attractant caused a 61.6% D. suzukii adult mortality rate. These results show the high potential of using M. brunneum in lure-and-infect and lure-and-kill strategies contributing to an integrated pest management program for D. suzukii control.