Functional response of Rhynocoris kumarii (Hemiptera: Reduviidae) to different population densities of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) recorded in the laboratory

摘要

Cotton mealy bug, Phenacoccus solenopsis Tinsley, a polyphagous pest is a serious threat to cotton production in several parts of Southeast Asia. Lack of an effective predator against this pest has resulted in the use of intensive chemical-based management strategies. Studies were carried out under laboratory conditions to determine the functional response of the adults and nymphs of a generalist reduviid predator, Rhynocoris kumarii Ambrose and Livingston, to different population densities (1, 2, 4, 6, 8 and 10) of P. solenopsis. Males, females and nymphs of this reduviid showed a type II functional response. There was no significant difference in the attack rate of male and female R. kumarii; however, prey-handling times of the sexes differed significantly. Of the sexes, males were more aggressive and killed a significantly higher number of third instar mealy bugs than females and had a Holling type II curvilinear functional response. Functional responses of the nymphal instars (third, fourth and fifth) and adults (female and male) of R. kumarii were more pronounced than those of the first and second nymphal instars. Results indicate that the nymphal instars of R. kumarii can be more effective at regulating P. solenepsis than adult reduviids. The findings of this study are important as they demonstrate the considerable potential of R. kumarii for controlling the cotton mealy bug, but now need to be evaluated under greenhouse and field conditions.