Rapid evolution of resistance to parasitism in biological control

Abstract

A growing awareness of human dependence on the natural capital of ecosystem services has highlighted the importance of such services to the sustainable management of both natural and production ecosystems. Biological control is an ecosystem service in which a pest, pathogen, or weed is effectively controlled through an ecological interaction (trophic or competitive) with its natural enemies, henceforth referred to as biological control agents (1). The control of an alien invasive species through the deliberate introduction of a specialist control agent from its geographic region of origin serves as one of the clearest examples of the value of biological control as an ecosystem service. A classic case is the successful control of the cassava mealybug ( Phenacoccus manihoti ) across the Central Belt of Africa following the introduction of a parasitoid wasp ( Anagyrus lopezi ) from South America (2). One surprising observation from the historical record of biological control is that although pests and weeds frequently become resistant to chemical pesticides (3), there has been no documented evidence of host resistance to an introduced parasitoid wasp (4). In PNAS, Tomasetto et al. (5) present the first clear example of the evolution of host resistance to an introduced parasitoid wasp from a study of the outcome of biological control of an invasive pasture weevil in New Zealand. The Argentine stem weevil ( Listronotus bonariensis ) was discovered in New Zealand in 1927 and became increasingly more damaging to grasslands with the intensification of livestock production in the 1980s. The deliberate introduction and establishment of an asexual population of a specialist parasitoid ( Microctonus hyperodae ) from South America in 1991 resulted in high levels of parasitism of adult weevils and successful suppression of the abundance of this invasive weevil. However, using a dataset on parasitism of overwintering Argentine stem weevils for the period from 1994 to 2015 … [↵][1]1Email: nmills{at}berkeley.edu. [1]: #xref-corresp-1-1