Unlocking the potential of native parasitoids as biological control agents of spotted wing drosophila
Marianna Szucs, an assistant professor in the Department of Entomology, assessed the viability of native parasitoids as a biological control.
Researcher: Marianna Szucs
Spotted wing drosophila (SWD) is an invasive pest of berry crops and cherries in Michigan. Unlike native drosophilids that attack only rotting fruit, SWD has a serrated ovipositor that allows it to attack harder, ripening fruit. The rapid development of SWD results in 8-10 generations a year, and it was introduced without its natural enemies, thus populations can grow unchecked causing serious economic losses for growers. Michigan is a major producer of blueberries and cherries in the U.S., accounting for 16% and 66% respectively of the US production. Thousands of tons of fruit, and millions of dollars, are at risk in Michigan from SWD.
Marianna Szucs, an assistant professor in the MSU Department of Entomology, worked to assess the viability of native parasitoids as a biological control. Currently, SWD is controlled using broad-spectrum insecticides that need to be applied weekly to counter the rapid development and large populations of SWD. With a zero-tolerance policy for infestation from the food industry for many crops, and the requirement of pre-harvest intervals without pesticide applications, SWD can quickly devastate harvests while also costing growers for increased spraying.
Classical biological control, which involves the importation and release of natural enemies from the native ranges on invasive pests could provide a long-term sustainable solution to reduce SWD populations on the landscape level. Implementation of a classical biological control program against SWD has been slow in North America, and the initial petitions to release two parasitoids had been rejected. Thus, in the absence of co-adapted natural enemies, the team investigated the potential of native North American parasitoids to attack SWD.
This research demonstrated that the development success of native parasitoids on SWD can be substantially improved within just three generations of artificial selection in the laboratory. These results lay the foundation for the next-generation of biological control in which native species, improved by selection, may provide an alternative or complimentary approach to importing exotic natural enemies.