Biological control of psocids (Psocodea: Liposcelididae) using the warehouse pirate bug, Xylocoris flavipes (Hemiptera: Anthocoridae)

Psocids (Psocodea: Liposcelididae) are important insect pests of stored-products worldwide and are difficult to manage using grain protectants and phosphine, hence research on non-chemical control methods. Studies were conducted to assess the potential of Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae) for managing psocids. The first and second objectives were to assess the predatory effectiveness of X. flavipes based on its functional and numerical responses when on a diet of Liposcelis decolor (Pearman) (Psocodea: Liposcelididae). Both adult females (adult♀) and nymphs of X. flavipes showed Holling Type II functional response when on diets of nymphs, adult males (adult♂) or adult females (adult♀) of L. decolor. The estimated functional responses variables showed that adult♀ X. flavipes performed better than the nymphs. The numerical response parameters indicated that adult♀ X. flavipes can increase their progeny production when prey densities are high and can establish at low prey densities. The third objective was to provide quantitative data based on the ecological interactions of X. flavipes and L. decolor under different predator-prey ratios (P-P ratios), temperatures (ºC) and relative humidities (RH %) over 40 days. The results showed that X. flavipes can suppress L. decolor population by >97% across all the P-P ratios and environmental conditions tested. Temperature influenced X. flavipes progeny production, was greatest at 28 ºC and a P-P ratio of 1:240. Relative humidity had no detrimental effect on X. flavipes. The fourth objective was to conduct a comparative assessment of the potential of three predators, X. flavipes, Cheyletus eruditus (Schrank) (Trombidiformes: Cheyletidae) and Cheyletus malaccensis Oudemans, to manage L. decolor populations using data from objective three and data from a separate previous study. The comparative evaluation showed that all three predators have the potential to manage psocids. However, X. flavipes can cause greater suppression levels than C. eruditus and C. malaccensis. Relative humidity of 63% was detrimental to both C. eruditus and C. malaccensis. Further evaluation of compatibility of X. flavipes with C. eruditus and C. malaccensis is required. Also, impact of pesticides on these predators should be investigated to facilitate their integration into IPM systems for management of psocids.