Submitted to: Biological Control
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/25/2003
Publication Date: 5/1/2004
Citation: Shapiro Ilan, D.I., Jackson, M.A., Reilly, C.C., Hotchkiss, M.W. 2004. Effects of combining an entomopathogenic fungi or bacterium with entomopathogenic nematodes on mortality of curculio caryae (Coleoptera: Curculionidae). Biological Control. 30:119-126. Interpretive Summary: The pecan weevil is a devastating pest of pecans. We are seeking new environmentally sound methods of controlling this pest. Insect-killing nematodes are small round worms that kill insect pests but don't harm people or the environment. Initial studies indicated that pecan weevil adults are very susceptible to insect-killing nematodes, but pecan weevil larvae are only moderately susceptible. The objective of this study was to determine if the nematode's ability to kill pecan weevil larvae might be increased if the nematodes are applied in combination with other natural insect diseases such as insect-killing bacteria and fungi. We found that applying the nematodes with other insect diseases did not substantially improve pecan weevil control, and in number of cases the combination decreased control.
Technical Abstract: Effects of combining entomopathogenic nematodes with other entomopathogens on ability to suppress pecan weevil larvae, Curculio caryae, were determined in the laboratory. Heterorhabditis indica or Steinernema carpocapsae was applied with Beauveria bassiana, Matarhizium anisopliae, Paecilomyces fumosoroseus, or Serratia marcescens. Antagnonism was observed in all pathogen combinations, except H. indica combined with M. anisopliae, and depending on rate, S. carpocapsae combined with B. bassiana or S. marcescens, for which additive effects were observed. The combination of H. indica and M. anisopliae may merit further study in other systems. Steinernema carpocapsae (applied alone) generally caused greater mortality than other pathogens applied alone. Paecilomyces fumosoroseus and S. marcescens were not pathogenic to C. caryae when applied alone. It was concluded that there would be little or no benefit to applying the pathogens in combination for C. caryae larval control.