Plant food effects on prey consumption by the omnivorous predator Macrolophus pygmaeus

Omnivorous predatory Heteroptera are important biological control agents of pests in several crops. They can feed on plant food resources that may positively affect their biological characteristics. In the current paper, the influence of leaves and flowers on the predation rate of the omnivorous predator Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) was investigated. Its predation rates were recorded on prey offered on (a) a single leaf of tomato, pepper or black nightshade (Solanum nigrum), or (b) a leaf of pepper or S. nigrum plus flowers of pepper or S. nigrum, respectively. In all cases the aphid Myzus persicae (Sulzer) (Homoptera: Aphididae) was used as prey at densities of 4, 8, 12, 16, 20 and 24 nymphs of the second instar. The experiments were conducted in petri dishes at 25 ± 1°C and prey consumption was evaluated after 24 h. The predation rate of M. pygmaeus was significantly higher on leaves of S. nigrum than on those of pepper at the prey density of 20 prey items. Therefore, the hypothesis that increased predation rates should occur on plants of lower suitability for development or reproduction was not supported under our experimental conditions. The flower availability did not alter the prey consumption among the prey densities on S. nigrum. However, the presence of a pepper flower caused a significant decrease in the predation rates on pepper leaves, at prey densities higher than eight prey items. Thus, pepper flowers can provide the predator with nutrient sources that may partially substitute for prey consumption, with practical implications in biological control.