Association between entomofauna and weeds in sugarcane (Saccharum officinarum L.)

Introduction. Weeds in sugarcane crops can serve as reservoirs of a wide variety of beneficial insects that are useful for biological pest control. Objective. To study the association between beneficial insects and weeds present in sugarcane field edges. Materials and methods. Monthly visits were conducted from April to December 2018 in two sites, El Palmar and Turrialba, two sugarcane regions in Costa Rica. Twenty random sampling points were selected where all insects within a cubic structure of 0,25 m3 were aspirated. Plant species were identified, as well as the families and morphospecies of insects present; the latter were classified based on their feeding habits. Subsequently, a co-occurrence analysis between weeds and insects was performed. Results. A total of 140 species belonging to 41 families were identified, with 83 species in El Palmar and 120 in Turrialba. Weed diversity and richness was higher in Turrialba. A total of 13 689 arthropods distributed across 137 families were identified; the diversity, richness, and abundance showed similarity between both sites. The families Poaceae and Cicadellidae were the most frequently identified in both areas. In the co-occurrence analysis, the weed Kyllinga brevifolia Rottb. exhibited a positive association (p<0.05) with predator insect families such as Coccinellidae, Syrphidae, and Dolichopodidae. Additionally, the parasitoid insect family Eulophidae was associated with eight weed species. Conclusions. The study revealed an association between weed species and beneficial insects in sugarcane cultivars, suggesting their role in maintaining populations of natural enemies for pest control.