The influence of intraguild competitors on reproductive decisions by two predatory Heteroptera, Orius insidiosus (Anthocoridae) and Nabis americoferus (Nabidae)

Authors: PUMARINO, LORENA - Agricultural Institute Of Spain; ALOMAR, OSCAR - Agricultural Institute Of Spain; Lundgren, Jonathan

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2011
Publication Date: 10/18/2011
Citation: Pumarino, L., Alomar, O., Lundgren, J.G. 2011. The influence of intraguild competitors on reproductive decisions by two predatory Heteroptera, Orius insidiosus (Anthocoridae) and Nabis americoferus (Nabidae). Biocontrol Science and Technology. 21(11):1321-1330.

Interpretive Summary: Minute pirate bugs (Orius insidiosus) and damsel bugs (Nabis americoferus) are two abundant omnivorous predators found in cropland throughout North America east of the Rockies. These two species have very similar biologies, and both insert their eggs into plant tissue. The literature suggests that these two species may partition a plant to reduce direct competitive interactions, and we empirically test this hypothesis here. The results show that reproductive pirate and damsel bugs alter their oviposition patterns in the presence of the other species. Pirate bugs lay their eggs on leaves, and shift their oviposition from the upper strata of a plant to the mid-region of the plant in the presence of the damsel bugs. In the presence of pirate bugs, damsel bugs lay more eggs on petioles and petiolules and in the top plant stratum than when pirate bugs are absent. We conclude that these important predators and potential competitors perceive one another when they reside on the same plant, and that they adjust their behavior. This behavior helps us to understand how complex predator communities persist within a habitat.

Technical Abstract: The relationship between the oviposition site preferences of predators in the face of intraguild competitors has received little attention, but it likely shapes the reproductive ecology of predatory species. In this study, oviposition intensity and the within-plant distribution of Orius insidiosus (Heteroptera:Anthocoridae) and Nabis americoferus (Heteroptera: Nabidae) eggs on Phaseolus vulgaris plants was studied when the two species were present independently or in combination. Both predators laid more eggs in the presence of the other species relative to when they were only exposed to conspecifics. When only exposed to conspecifics, O. insidiosus preferred to lay eggs on leaves and petioles on the upper half of the plant, whereas N. americoferus laid eggs mostly on the petioles and petiolules equally throughout the height of the plant. But when both species were present, O. insidiosus preferred to lay eggs on the leaf whereas N. americoferus altered their behavior to lay an even greater proportion of their eggs on the petioles and petiolules. They altered their preferences for different plant strata too: O. insidiosus was more likely to lay eggs lower on the plant in the presence of N. americoferus, and the latter species laid more eggs on the upper quarter of the plant when O. insidiosus was present. This study indicates that these two Cimicomorpha can detect the presence of one another, and that they adjust their reproductive decisions, presumably to avoid potential competitive interactions.