Functional Response and Predation Potential of Arma custos (Fabricius) Against Tuta absoluta (Meyrick)

The tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a globally invasive pest causing severe economic losses in tomato production. We evaluated the predatory stink bug Arma custos (Fabricius) (Hemiptera: Pentatomidae) using functional-response assays, a predator-density experiment, behavioral observations, Y-tube olfactometer bioassays, and a greenhouse cage trial. Depletion-aware maximum-likelihood models supported a Type III response for adult females feeding on second-instar larvae, whereas Type II models were retained for fifth-instar nymphs and adults feeding on fourth-instar larvae. At an initial density of 40 larvae, females consumed 16.2 ± 0.2 second-instar or 17.4 ± 0.5 fourth-instar larvae within 24 h. With 40 fourth-instar larvae available per arena, increasing female density from one to five reduced per capita consumption from 17.40 ± 0.51 to 5.44 ± 0.04 larvae per day. The Hassell–Varley model provided the best fit (m = 0.725; 95% CI, 0.693–0.755). In greenhouse cages, releasing three females per cage reduced cumulative damaged leaves by 60.12% by day 15. No active larvae were detected in release cages at that time, compared with 11.33 ± 0.33 in controls. Females preferred infested over healthy tomato plants, whereas males showed no significant preference. These findings demonstrate that A. custos is a promising biological control agent for integrated pest management (IPM) of T. absoluta.