Effects of Mineral Oils, Palizin and Buprofezin on Functional and Numerical Responses of Predatory Ladybeetle Cryptolaemus montrouzieri (Mulsant, 1850)
Predatory coccinellid, Cryptolaemus montrouzieri Mulsant is an important biological agent in citrus orchards. The effect of six treatments included: two types of mineral oils, EC and mayonnaise at the concentration of 15 ml/L, buprofezin 0.75 ml/L, buprofezin+EC oil 0.5+5 ml/L, insecticidal soap palizin 2.5 ml/L, and water as the control were investigated on the functional and numerical responses of C. montrouzieri Mulsant under laboratory conditions. The experiment investigated predation rate of female adult coccinellids to varying densities (2, 4, 8, 16, 32 and 64) of mealybug pray, Pseudococcus citri Risso. The relationship between the rate of consumption and pray density was explored with a logistic regression. The results of logistic regressions revealed that the rate of prey consumption by the predator had risen as prey density increased, but eventually leveled off in both the control and all insecticide treatments (following Holling’s type II functional response). Comparison of attack rates showed that the parameter significantly decreased when the predator was exposed to all insecticides but palizin. Predator handling times for oil mayonnaise, buprofezin and buprofezin+ EC oil treatments were significantly longer than that of the control. The longest handling time (1.6065 h) and the lowest attack rate (0.0351 h_1) were estimated for buprofezin+oil and oil EC treatments, respectively. As prey density increased, increase in oviposition and decrease in the food exploitation efficiency were observed. The results confirmed that the functional response of C. montrouzieri was affected by tested compounds reducing the predatory potential. The exception was palizin that had a low effect on functional response events of treated C. montrouzieri.