Management of Arna pseudoconspersa on Camellia oleifera with chemical pesticides and its residue analysis

Arna pseudoconspersa Strand is an important leaf-eating pest of many economic trees, particularly Camellia species. It's important to study the effects of its chemical control and the potential pesticide residue.

In this study, the leaf immersion method was used to determine the indoor toxicity of four pesticide chemicals and four pesticide formulations upon larvae of A. pseudoconspersa. Moreover, aerial pesticide application with a unmanned aerial vehicle was carried out at the Camellia oleifera forest, followed by the detection of pesticide residues in fruits after seven days.

Results showed that the indoor insecticidal activity of four pesticide ingredients ranged as emamectin benzoate > abamectin > chlorantraniliprole > tebufenozide. The median lethal concentrations (LC₅₀) of emamectin benzoate treatment for 1 day was 0.42 mg/L. Four pesticides, including 0.5% abamectin-aminomethyl microemulsion, 4.5% beta-cypermethrin emulsion in water, 6% bifenthrin · acetamiprid microemulsion, and 12% thiamethoxam · lambda-cyhalothrin suspoemulsion (SE), all showed excellent insecticidal activity against the larvae of A. pseudoconspersa. The mortality rates ranged from 83.3% to 98.3% as the lowest tested concentration of the four formulations treated for 3 days. 10% Thiamethoxam · lambda-cyhalothrin SE could control the erupt of A. pseudoconspersa effectively through aerial pesticide application. Furthermore, no pesticide residues had been detected in the seeds of Camellia fruit after 7 days, while varying levels of lambda-cyhalothrin were detected in the peels.

Thus, chemical pesticides, such as emamectin benzoate and thiamethoxam · lambda-cyhalothrin, could be used for the management of A. pseudoconspersa in Camellia tree forests, which would provide a scientific basis for the scientific prevention of related pests.