A molecular diagnostic for endosulfan insecticide resistance in the coffee berry borer Hypothenemus hampei (Coleoptera: Scolytidae)

The coffee berry borer Hypothenemus hampei (Ferrari) has recently evolved high levels of resistance to endosulfan and other cyclodiene-type insecticides in New Caledonia. During population outbreaks this has contributed to levels of infestation of Coffee berries reaching up to 90 percent. Using degenerate primers in the polymerase chain reation (PCR) we have amplified a section of the cyclodiene resistance gene Rdl from H. hampei. This gene codes for a y-aminobutyric acid (GABA) gated chloride ion channel. Here we report that resistant strains of H. hampei carry exactly the same single amino acid replacement (alanine to serine) as that found in resistant Drosophila melanogaster (Meigen) (Diptera: Drosophilidae). A molecular diagnostic based upon PCR-mediated amplification of specific alleles (PASA) is described. This technique is capable of detecting resistance or susceptibility in adults larvae or eggs but not in susceptible females carrying resistant sperm. Its potential use in field monitoring is discussed.