Biological and behavioral effects of kaolin particle film on larvae and adults of Chrysoperla carnea (Neuroptera: Chrysopidae)

Abstract

Several laboratory and field experiments were conducted to investigate the effect of kaolin particle film formulation Surround WP on the biology and behavior of the common generalist predator Chrysoperla carnea (Stephens). Kaolin 5% (w/v) suspension direct spray did not affect third instar larvae development to adulthood. The hatchability of recently laid eggs, subjected to the same spraying process, was also unaltered. However, third instar larvae coated with particle film after kaolin spraying showed slightly hampered movement capacity after measuring: distance moved, mean velocity, angular velocity and time spent in motion, obtained using the computerized system EthoVision. Parameters extracted from recorded larvae movement on a kaolin film surface showed similar decreased mobility results as well as preference for the clean control surface. Additionally, the larvae had difficulty grasping treated leaves. C. carnea adult females showed a predominant preference for treated leaves in oviposition choice tests. In the field trial, no difference in C. carnea adult abundance was found between kaolin-treated and control olive trees. These results indicate that disruption of movement capacity and dislodgement from the plant surface may be the principal negative effects of particle film on C. carnea larvae. Despite the positive trend in oviposition towards kaolin treated surfaces, a particle film attraction effect on adults was not observed at field level.