Interactions between the nematode Heterorhabditis amazonensis JPM4 and the predator Macrolophus basicornis: two natural enemies of Tuta absoluta native to South America

Abstract

Entomopathogenic nematodes (EPNs) and predatory mirids are among the most effective natural enemies for the control of Tuta absoluta, a key pest of tomato worldwide. In the case of South America, the native EPN Heterorhabditis amazonensis and the predator Macrolophus basicornis (Stal) coexist in tomato. The intraguild interactions of two ENPs, H. amazonensis JPM4 and the widely used Steinernema carpocapsae, with the predator M. basicornis, were studied in laboratory setups with the objective of evaluating the potential interactions between them. We hypothesized that the two natural enemies do not interact negatively. The first nymphal stage of the predator was not affected when exposed to tomato leaves directly sprayed with both EPNs, which we attributed to the small size of its stylet. Individuals treated with H. amazonensis JPM4 had low mortality rates in all developmental stages with a maximum of 1.3%. Mortality was higher when the predator was exposed to S. carpocapsae (28% for adults) and correlated positively with increasing developmental stages. In prey choice tests between larvae infected with H. amazonensis and uninfected larvae, M. basicornis fed indistinctively showing no clear preference. When presented with choice larvae infected with S. carpocapsae, the consumption of healthy larvae was higher. In a no-choice prey acceptance experiment, M. basicornis preyed on both healthy and infected larvae with no difference in larvae consumed. Predators that had fed from infected larvae did not exhibit signs of nematode infection and survived. Our results indicate that the South American native H. amazonensis JPM4 and M. basicornis do not show a negative interaction and are promising candidates for combined use in T. absoluta biological control.