Influence of natural vegetation conservation on the distribution of mites in rubber tree crops

Abstract

The remnants of natural vegetation can act as reservoirs of natural enemies that control pest populations in crops, thus, optimizing agricultural production. Here, we assessed whether the conservation of native vegetation in agricultural landscapes affects the abundance and richness of mites in rubber tree plantations. For this purpose, we sampled 17 landscapes that encompassing rubber tree crops either adjacent or close to natural vegetation remnants. To infer the conservation status of vegetation remnants, we used five landscape variables. Then we used Linear Mixed Models (LMM) to test the effect of conservation status metrics on the abundance and richness of mites, density of Calacarus heveae and leaf damage. We collected 1,335 mites with phytophagous being the most abundant guild, followed by predatory and mycophagous mites. We found a negative effect of habitat fragmentation on the abundance of phytophagous mites. Predatory mites abundance in rubber tree crops was positively affected by both habitat heterogeneity and complexity, as well as by the aggregation index. Likewise, the abundance of mycophagous species was also positively correlated with habitat heterogeneity. Phytophagous and predatory species richness, C. heveae density, and symptoms of leaf damage by phytophagous were not affected by the landscape metrics tested herein. These results highlight the importance in keeping natural remnants in agricultural landscapes since native vegetation can serve as refuge and reservoir for predatory mites, which colonize crops, and can contribute to biological pest control.