AbstractBetter performance of generalist predators, as well as an increase in their density, may be an incentive factor in the ability of the predators to exploit more than one food item or mixed diets. In this study, the effects of four pollen grains (cedar, pear, apricot, and pistachio) when provided to Neoseiulus californicus in mixed diets with prey, Tetranychus urticae, were evaluated. The result indicated that the fastest female developmental time was observed on pistachio pollen + T. urticae, together with apricot pollen + T. urticae. Females reared on the mixed diet comprising pistachio pollen reflected the longest total life span duration, while the shortest total life span was observed in those on the diet that included pear pollen. Furthermore, the lowest fecundity, as well as the shortest reproduction period, was determined on the diets that included pear pollen, while the highest fecundity and the longest reproduction period were observed in pistachio pollen + T. urticae. In addition, the intrinsic (r) and finite rate of increase (λ), net (R0) and gross (GRR) reproductive rates were highest in pistachio pollen + T. urticae. These findings have important implications for developing a comprehensive biological control program of T. urticae, which will be discussed.

Alternative foods such as pollen may help predators to maintain their populations even when their prey is scarce or absent. In order to develop an appropriate spider mite management strategy using Neoseiulus californicus McGregor and optimize laboratory rearing, its biological parameters on four types of pollen (cedar, pistachio, pear, and apricot) were determined and compared on Tetranychus urticae Koch. Our results indicated that the developmental times of females and males varied from 6.06 to 7.32, and 6.00 to 7.15 d, respectively. The highest fecundity was obtained on pistachio pollen, followed by apricot pollen and T. urticae. Feeding on cedar pollen caused the lowest fecundity. In contrast to T. urticae and pistachio pollen, which resulted in the highest intrinsic and finite rates of increase, feeding on cedar pollen produced the lowest value. Pistachio and apricot pollen appear to have the highest nutritional value. From an ecological perspective, in the presence of pistachio pollen, a more rapid population increase of N. californicus could be expected, when the prey is scarce or absent in greenhouses or fields. This may provide valuable information for the design of a comprehensive program for conservation and/or mass production of N. californicus to control T. urticae and other pests.