Efficacy of pea flour as an antifeedant against two stored-food mites (Acari: Acaridae) fed on dried medicinal Chinese herbs

Pea flour (Pisum sativum L.) is toxic to some stored-product pests. Botanical pesticides that contained efficient natural compounds have highlighted to be used for the control of storage mites. In the current investigation, we evaluated the effect of pea flour as an antifeedant on two stored-product mites, namely Tyrophagus putrescentiae (Schrank, 1781) and Aleuroglyphus ovatus (Troupeau, 1878) fed on two medicinal Chinese herbs: Crataegus pinnatifida Bge. var. major and Coix lachryma-jobi L. var. ma-yuen. The experiment was carried out from March to May 2012 under the optimal growth conditions of storage mites at constant temperature (25°C) and 85 ± 5% relative humidity (RH) in the dark. Pea flour was used at five concentrations (0, 0.01, 0.1, 1 and 10%). The values of LC₅₀, LC₉₀ and mortality of T. putrescentiae and A. ovatus were recorded at four periods (7, 14, 21 and 28 days), while their population dynamics were determined only after 21 days. The use of pea flour as an antifeedant was very efficient for the control of T. putrescentiae and A. ovatus adults. The controlling efficiency of pea flour improved due to the increase of its applied dose. The LC₅₀ and LC₉₀ estimates showed that pea flour was more toxic for T. putrescentiae than for A. ovatus. The concentration of 1% pea flour was responsible for more than 65% and 88% mortality of A. ovatus on C. pinnatifida and C. lachryma-jobi after 28 days, respectively. However, this concentration was sufficient to kill all individuals (100% mortality) of T. putrescentiae as the concentration of 10% pea flour. The addition of pea flour caused considerable decreases in the rate of the increase (r-value) of T. putrescentiae and A. ovatus. The highest r-values of T. putrescentiae and A. ovatus were recorded on the control treatment (0% pea flour), whereas the lowest values were observed at 1% and 10% concentrations of pea flour. The 1% concentration of pea flour is highly suggested to be used as a good and economical dose to control both of T. putrescentiae and A. ovatus on the studied Chinese herbs.