Effect of Spatiotemporal Association and Trophic Interactions between Aphidophagous Coccinellids Toward Aphid Control

Abstract

Predator diversity in a system can have different results on the biological control of pests. Positive results can arise if natural enemies have niche complementarity, whereas negative effects can occur when one enemy interferes with heterospecifics - e.g., via intraguild predation - resulting in weaker pest suppression. Nevertheless, a coexistence is possible if enemies use the resource differentially leading to resource partitioning, and/or if the intraguild prey has some competitive advantage over the intraguild predator - i.e., is better at exploiting the shared resource or exhibits avoidance behavior. In this study, we conducted a series of field-sampling and semifield experiments to elucidate the spatiotemporal association patterns of the coccinellids Eriopis connexa (Germar) and Cycloneda sanguinea L. (Coleoptera: Coccinellidae) and determine how the trophic interactions between them could affect the biological control of aphids. We found that both coccinellid species coexist in sweet-pepper crops over time, and this coexistence could be explained by a temporal niche complementarity. Despite cooccurring spatially, they were segregated at the leaf level, which segregation can be explained by an avoidance behavior to prevent negative trophic interactions, such as cannibalism and intraguild predation. Under semifield conditions, the possible negative trophic interactions did not affect the control of aphids when both species were present, but the density of C. sanguinea was reduced at the end of the experiment. These results suggest that biological control strategies that include both species would be positive for the control of aphids on the basis of these considerations.