Tritrophic interactions among bean (Vicia faba L.), two herbivores [Aphis fabae scopoli and Acyrthosiphon pisum (Harris)] and two predator (Hippodamia variegata and Coccinella septempunctata)

Chemicals are used extensively against pests in the area where crop production. As a result, pests also gain resistance and therefore, it is thought that alternative control methods should be available. One of them is the biological control method, and in this method, determining the prey-predator relationship and reproductive abilities in varying prey densities are key components in the selection of biological control agent. In this study, predators' orientation to different foods was investigated with the help of an olfactometer. In this study, functional and numerical responses of Hippodamia variegata and Coccinella septempunctata (Coleoptera: Coccinellidae), which are predators of aphids, were also tested. In functional response experiments, the amount of prey consumed by different prey densities and the effect of predators on decreasing the populations of aphids was determined; while in numerical response experiments, the reproductive abilities of the predators at varying prey densities were designated. All of the studies were carried out in climate chambers with 27 ± 1 °C temperature and 65±5% proportional humidity and long day lighting (16: 8). According to the results obtained in the functional response experiments, it was observed that the attack rates (a) of the predator insects on their prey increased as the development period progressed, and the handling time (Th) decreased. In the numerical response experiments, it was determined that the number of eggs laid and the reproductive responses (ECI) of both predators on their food increased depending on the prey density. According to the data obtained, it has been concluded that both predators have high reproductive consumption and reproductive capacity on A. fabae and A. pisum, especially in the late development stages, and they can be effective in control these pests.