Effect of hosts and diet on the reproduction and cannibalism in Nabis americoferus, a potential biological control agent of tarnished plant bugs in greenhouses

Tarnished plant bugs (TPB) and aphids are important pests of greenhouse crops. Generalist predators can be a biological control solution to tackle multiple pests. The bug Nabis americoferus is a main predator of TPB and aphids. However, the rearing parameters of this insect must be optimized. The objective of this study is to measure the impact of diet and host on the egg-laying behavior of N. americoferus and to measure the rate of cannibalism based on the availability of food resources. In a first experiment, either aphids, TPB, eggs of Ephestia or cysts of Artemia were offered to Nabis. Ephestia’s eggs cause the most egg-laying in Nabis, while Cysts of Artemia and TPB have a negative impact. The effect of the host plant on egg-laying was tested by offering either an eggplant, buckwheat or canola to Nabis. No statistical differences were observed between these hosts, but results varied widely for buckwheat and canola compared to eggplants. Finally, the rate of cannibalism on the nymphs was measured according to the diet (control, aphid or Ephestia’s eggs) and the presence of an advanced stage. Ephestia’s eggs and aphids reduce the rate of cannibalism. The presence of advanced stage causes a significant increase in cannibalism regardless of the food resources available. Our results demonstrate that Nabis rearing is optimal when Ephestia eggs are offered as food resources. The choice of host plants may be based more on logistical and financial considerations than on their effect on the biology of the Nabis.