Predation preference of Neoseiulus californicus and Typhlodromus bagdasarjani on heterospecific phytoseiid and Scolothrips longicornis in presence and absence of Tetranychus urticae

摘要

Predation preference of Neoseiulus californicus (McGregor) and Typhlodromus bagdasarjani Wainstein & Arutunjan on Scolothrips longicornis Priesner and heterospecific phytoseiid was determined on cucumber leaf discs in presence and absence of Tetranychus urticae Koch . The experiments were conducted under laboratory conditions at 25?C, 65% RH and a photoperiod of 16h light: 8h dark. The first and second instar of the thrips and larval stages of the phytoseiids were selected as intraguild preys. In the first experiment, the first or second instar larvae of the thrips and heterospecific larval phytoseiid (regarded as predator species) were offered to an adult female of phytoseiid. The females of N. californicus and T. bagdasarjani significantly preferred to prey upon the first instar larvae of the thrips (1.82 and 1.41 larvae per day, respectively) compared with phytoseiids (0.78 and 0.53 larva per day, respectively). Consumption of the two mentioned phytoseiid species on second instar larvae of the thrips (0.96 and 0.60 larva per day, respectively) and the phytoseiid (0.91 and 0.62 larva per day, respectively) were not significantly different. The females of both phytoseiid species were able to oviposit continuously when fed on the thrips and phytoseiid preys. In the second experiment, when T. urticae , the phytoseiid and thrips were offered simultaneously, both phytoseiid species could prey upon all three species but T. urticae was significantly consumed more (5.52 T. urticae per day by N. californicus and 4.46 T.urticae per day by T. bagdsarjani ). Since these two predators belong to the type III phytoseiids, it seems that both species were able to survive in absence of T. urticae and tend to prey more on first instar larvae of the thrips compared with the heterospecific phytoseiid.