Trophic relationship between Chrysoperla externa (Neuroptera: Chrysopidae) and Planococcus citri (Hemiptera: Pseudococcidae) associated with rose bushes

ABSTRACT

ABSTRACT This study aimed to determine the consumption of Planococcus citri (Risso, 1813) (Hemiptera Pseudococcidae) nymphs and the predatorprey ratio required for high predatory efficacy and survival of Chrysoperla externa (Hagen, 1861) (Neuroptera Chrysopidae) larvae under different densities of prey, reared in rose bushes. Consumption by first-, second-, and third-instar larvae of C. externa was assessed. The predatory efficiency and survival of the predator were calculated for larvae in the second instar under densities of 20, 40, 80, 120, and 160 nymphs of P. citri and predatorprey ratios of 15, 110, and 120. The assessments were performed after 24 and 48 hours of exposure between species. There was increasing consumption throughout the larval development of C. externa. The predatorprey ratios 15 and 110 were the most efficient for P. citri population reduction, but the 15 ratio led to lower survival of larvae than the 110 and 120 ratios. There was a positive correlation between C. externa larval density and cannibalism (ρ = 0.45) and a negative correlation between predator density and P. citri population density (ρ = -0.81). Third-instar larvae consume more P. citri nymphs than second-instar larvae. Second-instar larvae of this lacewing released at a 120 ratio caused total mortality of mealybug nymphs within 48 hours, regardless the density of P. citri, with high larvae survival of C. externa.