Dicyphine mirids are important biological control agents (BCAs) in horticultural crops. Dicyphus cerastii Wagner can be found in protected tomato crops in Portugal, and has been observed feeding on several tomato pests. However, the predation capacity of this species is poorly studied. In order to investigate the predation capacity of D. cerastii, and how it is affected by prey size and mobility, we evaluated the functional response (FR) and predation rate of female predators on different densities of four prey species: Myzus persicae 1st instar nymphs (large mobile prey), Bemisia tabaci 4th instar nymphs, Ephestia kuehniella eggs (large immobile prey) and Tuta absoluta eggs (small immobile prey). Experiments were performed on tomato leaflets in Petri dish arenas for 24 h. Dicyphus cerastii exhibited type II FR for all prey tested. The predator effectively preyed upon all prey, consuming an average of 88.8 B. tabaci nymphs, 134.4 E. kuehniella eggs, 37.3 M. persicae nymphs and 172.3 T. absoluta eggs. Differences in the FR parameters, attack rate and handling time, suggested that prey size and mobility affected predation capacity. Considering the very high predation rates found for all prey species, D. cerastii proved to be an interesting candidate BCA for tomato crops.

Despite their importance as biological control agents, zoophytophagous dicyphine mirids can produce economically important damage. We evaluated the phytophagy and potential impact on tomato plants of Dicyphus cerastii and Nesidiocoris tenuis. We developed a study in three parts: (i) a semi-field trial to characterize the type of plant damage produced by these species on caged tomato plants; (ii) a laboratory experiment to assess the effect of fruit ripeness, mirid age, and prey availability on feeding injuries on fruit; and (iii) a laboratory assay to compare the position of both species on either fruit or plants, over time. Both species produced plant damage, however, although both species produced scar punctures on leaves and necrotic patches on petioles, only N. tenuis produced necrotic rings. Both species caused flower abortion at a similar level. Overall, N. tenuis females produced more damage to tomato fruit than D. cerastii. There was an increased frequency of D. cerastii females found on the plants over time, which did not happen with N. tenuis. Our results suggested that, although D. cerastii caused less damage to fruit than N. tenuis, it still fed on them and could cause floral abortion, which requires field evaluation and caution in its use in biological control strategies.

Dicyphus cerastii Wagner (Hemiptera: Miridae) is an important predator in horticultural crops. This study provides the first data on biological traits like development, survival, and reproduction for this species. We investigated how host (tomato, tobacco, and Cape gooseberry) and temperature (15.0, 20.0, 25.0 ± 1 °C) influenced nymphal development, survival, and adult longevity. In the absence of prey, nymphs failed to complete development on any host. When prey was available, nymphal development, survival and longevity declined as temperature increased across all hosts. Development and longevity of D. cerastii were further examined on tomato, at seven temperatures (15.0, 20.0, 25.0, 27.5, 30.0, 32.5, 35.0 ± 1°C). Reproductive capacity was measured at 20.0, 25.0, 30.0 ± 1°C, on tomato. Egg development ranged from 30.6 days (15.0 °C) to 9.7 days (32.5 °C). Nymph development decreased from 40.0 days (15.0 °C) to 16.4 days (30.0 °C), and no nymphs completed development above 30.0 °C. The optimal temperature for development from egg to adult was estimated at 29.2 °C., while the minimum threshold for immature development was approximately 7.0 °C. The thermal constant for development was 230.4 degree-days for eggs, and 394.0 degree-days for nymphs. Adult longevity ranged from 158.6 days (15.0 °C) to 13.8 days (30.0 °C). The net reproductive rate (R₀) and generation time (T) were highest at 20.0 °C, while the intrinsic rate of increase (r_m) was highest at 25.0 °C.