The newcomer takes it all: the invader Texas citrus mite, Eutetranychus banksi (Acari: Tetranychidae), displaces the resident relatives in citrus agrosystems

Abstract

Many studies have emphasized the importance of interspecific competition in shaping natural ecosystem communities. In contrast, few investigations have explored the role of competition in agricultural environments after the arrival of an invasive pest species. We evaluated the ecological impact produced by the invasive Texas citrus mite, Eutetranychus banksi (McGregor), on the resident spider mites Panonychus citri (McGregor) and Eutetranychus orientalis (Klein) on the main citrus crop area in Eastern Spain. Since its arrival in 2013, E. banksi has become the most common and abundant spider mite on citrus, apparently leading to a reduction in the presence and geographic range of the other related species. Competitive relationships were detected between E. banksi–E. orientalis and E. banksi–P. citri pairs using co-occurrence analysis. Furthermore, generalized linear model analysis showed that the probability of finding E. orientalis or P. citri decreases with increasing E. banksi density and vice versa. Principal component analysis and permutational multivariate analysis of variance found competition between these two pairs, and also between the E. orientalis–P. citri pair. Redundancy and variation partitioning analysis revealed how the geographic distribution of the three spider mites is not caused by the environmental conditions, but it is strongly influenced by their colonization history and competitive relationships, since the areas with the highest density of the three species are related to their place of first detection, and do not coincide geographically. Finally, the mechanisms that may be involved in the competitive displacement and the possible future scenarios are discussed.