Potencial de Chrysoperla externa no controle de Planococcus citri e Macrosiphum rosae provenientes de roseiras

Abstract

The use of natural enemies to reduce phytophagous arthropod populations in crops is widespread. However, there is little information on the use of Chrysoperla externa (Neuroptera: Chrysopidae) against the aphid Macrosiphum rosae (Hemiptera: Aphididae) and the mealybug Planococcus citri (Hemiptera: Pseudococcidae) associated with rose bushes. The objectives of this work were 1) to study the effect of the preys P. citri, Ephestia kuehniella (Lepidoptera: Pyralidae), and M. rosae, provided in combination or not, on the biological and population characteristics of C. externa; 2) determine the consumption of P. citri nymphs and the predator-prey ratio required for predatory efficacy and larvae survival under different prey densities; 3) to evaluate the consumption of M. rosae nymphs and adults by C. externa, predatory efficiency and larval survival against different predator:prey ratios, aphid densities and ages. The experiments was carried out at the temperature of 25 ± 1ºC, relative humidity of 70 ± 10%, and a 12-hour photophase. The prey derived from rose bushes cv. Avalanche. The supply of E. kuehniella eggs, at least in the first instar, provided the development and ensured greater viability and production of eggs compared to those that consumed P. citri nymphs, exclusively. In general, the consumption of M. rosae nymphs and adults provided the predator performance, similar to the treatment consisting of E. kuehniella eggs. The consumption of aphids and mealybugs increased throughout the larval development of C. externa. Higher predator:prey proportions against mealybugs and young aphids resulted in greater predatory efficiency but lower larvae survival. We found that the mealybug P. citri is a suitable prey for the development and reproduction of C. externa when the first instar larvae are fed on E. kuehniella eggs. When supplied throughout the larval period or from the second instar, the aphid M. rosae is a suitable prey for the predator, having been fed on E. kuehniella eggs in the first instar. Third instar larvae consume more mealybugs and aphids than other instars and a higher number of young aphids compared to older ones. Second instar larvae of C. externa used in a 1:10 ratio are more efficient in reducing the P. citri population and present high and moderate survival after 24 and 48 hours of interaction with the prey, respectively. The 1:5 and 1:10 proportions provided the elimination of young and older aphid populations of M. rosae after 72 hours of exposure between species. In conclusion, C. externa larvae can reduce P. citri and M. rosae populations and be selected for the management of these pests in rose crops.