Chlorfenapyr-based Insecticide Induces Midgut Damage in the Tomato Leaf Miner Phthorimaea absoluta Meyrick, 1917 (Lepidoptera: Gelechiidae) Larvae

Pesticide resistance in agricultural pests has become a growing concern, as many species have developed resistance to most commercially available insecticides. Phthorimaea absoluta Meyrick, the tomato leaf miner, is one of the most destructive pests of tomato crops, capable of causing severe damage and even complete yield loss. This species has shown high levels of resistance to various insecticides, complicating effective pest management. Chlorfenapyr is a pro-insecticide that disrupts mitochondrial ATP production, ultimately leading to insect death. This study evaluated the lethal, sublethal, and histopathological effects of a chlorfenapyr-based insecticide on P. absoluta larvae through oral exposure. Lethal concentrations were determined using a concentration-mortality bioassay, and the LC₅₀ value (3.72 ppm) was applied to assess histopathological alterations in the midgut. Chlorfenapyr-based insecticide exhibited high toxicity against P. absoluta. Histopathological and histochemical analyses revealed midgut epithelial damage, morphological alterations associated with cell degeneration, as well as the elimination of mycetocytes, which may play roles in digestion and xenobiotic detoxification. These findings provide one of the first histopathological characterizations of pesticide effects in this species and in microlepidoptera more broadly, reinforcing the potential use of chlorfenapyr within integrated pest management strategies.