Aportes de franjas de Thinopyrum intermedium a la gestión integrada de plagas del cultivo de soja

Soybean (Glycine max) is the main agricultural crop in Uruguay, but its intensification poses serious challenges for pest management due to insect resistance and environmental contamination. In this context, Integrated Pest Management (IPM) promotes the use of reservoir areas to enhance the presence and abundance of natural enemies. The general objective of this study was to evaluate the contribution of Thinopyrum intermedium (intermediate wheatgrass), a winter perennial grass of dual purpose, to IPM in soybean crops. The specific objectives were to examine the effect of distance from T. intermedium strips on the abundance of predatory and herbivorous arthropods. We hypothesized that predator abundance would decrease and herbivore abundance would increase with increasing distance from the strips. The experiment was conducted at EEMAC, Paysandú, Uruguay, using four permanent T. intermedium strips parallel to the soybean crop. Sampling points were established in the tinopiro, in a strip of spontaneous vegetation, and within the soybean crop at 10, 25, 40, and 55 meters from the edge. Sampling was carried out biweekly using an entomological sweep net in all habitats and a vertical beat cloth within soybean. Abundance in each habitat (T. intermedium, spontaneous vegetation, and soybean) was analyzed using Generalized Linear Mixed Models (GLMM) with a negative binomial distribution due to overdispersion. Habitat was included as a fixed effect, and date and block as random effects. When “Habitat” was significant, post-hoc comparisons were performed using the emmeans package with Sidak adjustment to detect differences among habitats. In addition, arthropod abundance was modeled through GLMM with a negative binomial distribution, using distance from tinopiro as a fixed effect and date and block as random effects. Models with linear and quadratic terms were compared, selecting the best according to AIC. A total of 7,389 arthropods of interest were collected, 34% of which were natural enemies (predators and parasitoids). The abundance of natural enemies and predators was significantly lower in soybean than in tinopiro and spontaneous vegetation. Their abundance decreased linearly and progressively with increasing distance from the tinopiro toward the interior of the crop. Tinopiro presented higher abundances of lacewings and spiders. In contrast, herbivores were concentrated in soybean. Our results indicate that the inclusion of Thinopyrum intermedium strips is a promising strategy for enhancing the presence of beneficial arthropods and contributing to the functional diversification of the system. Perennial strips act as key refuges and resource sources for natural enemies. The pattern of decreasing predator abundance and the concentration of herbivores in soybean (farther from the edge) reinforces the hypothesis that tinopiro may indirectly contribute to natural pest control through the conservation of natural enemies in the immediate vicinity of the crop. Thus, tinopiro emerges as a multifunctional component that integrates production (grain and forage) with the conservation of beneficial fauna, aligning with the principles of ecological intensification to achieve more sustainable agricultural–pastoral systems in Uruguay.