Influence of plants used in agricultural diversification on the nematode Heterorhabditis amazonensis

Abstract

In an agricultural system, to increase natural biological control, plants that attract natural enemies can be grown alongside the main crop. However, the effects of these plants on entomopathogenic nematodes (EPNs), important agents for controlling soil pests, and the action of their conservation are unknown. To assess the impact of these plants on EPNs, two experiments were carried out in a greenhouse. The first measured the effect of Crotalaria spectabilis, Crotalaria breviflora, and Tagetes erecta on the persistence and infectivity of Heterorhabditis amazonensis isolate RSC 5 for 27 days, compared to a control treatment without plants. The second trial evaluated the effect of C. breviflora and T. erecta on the displacement of the nematode. Additionally, the influence of predator Calosoma granulatum in this system was evaluated. The plants did not influence nematode behaviour in terms of persistence, infectivity, or displacement. However, C. spectabilis allowed the most significant persistence of nematodes in the substrate for a short time, and T. erecta caused the fastest suppression of the initial population of infectives juvenile. In the second experiment, neither the predator nor the plants affected the nematode's ability to move in the soil within 5 days. These results show that prior knowledge in agricultural diversification can help to control pests by inundative application of EPNs.