https://doi.org/10.37229/fsa.fja.2026.08.15

The red palm weevil, Rhynchophorus ferrugineus (Olivier), is a destructive pest of palm trees, and its concealed larval habit makes effective management difficult. The present study evaluated the pathogenicity of six entomopathogenic agents, including Beauveria bassiana, Metarhizium anisopliae, Steinernema carpocapsae, Heterorhabditis bacteriophora, Bacillus thuringiensis, and Bacillus subtilis, against third- and sixth-instar larvae of R. ferrugineus under laboratory conditions. A series of concentrations was tested, and larval mortality was recorded at different post-treatment intervals. LC₅₀, and LC₉₀ values were estimated using probit analysis. All tested agents exhibited pathogenic activity, with mortality generally increasing with exposure duration. B. bassiana showed the highest toxicity among the tested fungi, while S. carpocapsae and B. subtilis were the most effective agents among the tested nematodes and bacteria, respectively. The LC₂₅ concentrations were subsequently used to evaluate sublethal developmental effects. Exposure to LC₂₅ significantly reduced final larval weight, weight gain, and molting rate, while prolonging the time required for molting to the subsequent instar in both larval stages. The results demonstrate that the tested entomopathogenic agents can exert both lethal and sublethal effects on R. ferrugineus larvae and highlight their potential as biological control agents for inclusion in integrated management programs.