Interactions Between Arma chinensis and Entomopathogenic Nematodes for Biological Control of Tuta absoluta

The tomato leafminer Tuta absoluta (Meyrick) is a devastating invasive pest that threatens tomato production worldwide. Reliance on chemical insecticides raises sustainability concerns, highlighting the need for effective biological alternatives. Combining predators with entomopathogenic nematodes (EPNs) represents a promising strategy, yet their interactions remain poorly characterized. Here, we conducted laboratory bioassays to assess the individual and joint effects of the predatory bug Arma chinensis (Fallou) and four EPN species, Steinernema carpocapsae, S. feltiae, S. riobrave, and Heterorhabditis bacteriophora, against T. absoluta larvae. Under these controlled conditions, H. bacteriophora showed the highest compatibility with A. chinensis, exhibiting the lowest virulence against the predator. Female A. chinensis exhibited strong predation on freely exposed second-instar larvae, but efficiency declined markedly against leaf-mining larvae. Heterorhabditis bacteriophora caused consistently high mortality in second instars regardless of protection. Their combined application resulted in additive mortality with significantly reduced LT50 values. We also observed A. chinensis preying on nematode-infected larvae and occasional infection of the predator under confined conditions. These laboratory findings demonstrate additive effects against T. absoluta, providing preliminary evidence for stage-specific integrated biological control strategies.