Weeds as hosts for new crop pests: the case of Protortonia navesi (Hemiptera: Monophlebidae) on cassava in Brazil

Abstract

SummaryWeeds may serve as reservoirs for new and invasive insect pests. The cassava root scale (Protortonia navesi) is a recent pest in the Brazilian ‘Cerrado’ that causes qualitative and quantitative damage by sucking plant sap. Recently, field surveys revealed that many common weeds in this region act as host for P. navesi in cassava fields. In a discrete survey, 15 weed species were identified that were hosting P. navesi. Among these, 13 species occurred during the cropping season and five were observed 4 months after cassava harvest. Eight months after harvest, only cassava volunteer plants were found to be hosting P. navesi. This survey provided a real example of the problem created when weeds host new crop pests. The management of weeds (including crop volunteers) needs to be considered as part of generalised pest management and pest invasion prevention schemes. Effective weed management can be a means of limiting the survival of new pests and the re‐infestation of susceptible crop species in subsequent years. Simple studies like this point to a practical need to create greater collaborations between pest management researchers working within discrete pest categories.