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

Abstract

This study aimed to determine the consumption of Planococcus citri (Risso, 1813) (Hemiptera: Pseudococcidae) nymphs and the predator:prey 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 predator:prey ratios of 1:5, 1:10, and 1:20. 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 predator:prey ratios 1:5 and 1:10 were the most efficient for P. citri population reduction, but the 1:5 ratio led to lower survival of larvae than the 1:10 and 1:20 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 1:20 ratio caused total mortality of mealybug nymphs within 48 hours, regardless the density of P. citri, with high larvae survival of C. externa.

Inter - and intraspecific relationships between Macrosiphum rosae (Hemiptera: Aphididae) and Chrysoperla externa (Neuroptera: Chrysopidae)

“…The second-instar larvae of C. externa were released in these containers at predator:prey ratios of 1:5, 1:10, and 1:20, according to the initial density of aphids. Thus, for the 1:5 ratio, 4, 8, 16, 24, and 32 larvae were added; for the 1:10 ratio, 2, 4, 8, 12, and 16 were added; and for the 1:20 ratio, 1, 2, 4, 6, and 8 larvae were added, similar to the method adopted by Gamboa et al (2016) and Carvalho et al (2022). In the period before release, the larvae were fed (ad libitum) E. kuehniella eggs.…”