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Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), an economically important biocontrol agent, was reared on almond pollen for 50 generations. We evaluated the effect of rearing predators on this pollen by comparing biological parameters at different generations (G1–G50). The shortest and longest development time occurred in G5 and G10, respectively. Females at the fifth and 50th generations laid eggs earlier than those of other generations. Females at G50 laid eggs over a longer period and produced more eggs than females of other generations, although females in the earlier generations had a higher gross reproductive rate and net reproductive rate than later generations. The intrinsic rate of increase, as well as the finite rate of increase of N. cucumeris in the fifth and 50th generations was significantly greater than those in other generations, while the first generation had the lowest values of these parameters. The dorsal shield length of both females and males and the width of females were found to be unaffected by their constant feeding on almond pollen. However, the number of rearing generations significantly affected the width of males. Long-term rearing of N. cucumeris for at least 50 generation on almond pollen did not substantially affect the predator's quality and this food source could be used for the mass production of this predator. Almond pollen should be assessed in rearing other phytoseiid mites that are important in biocontrol strategies.

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Using the most suitable alternative diets that are easily available and less expensive than the natural diets may give rise to reduce the rearing costs of natural enemies. Alternative or additional food used for this purpose should be in accordance with the food spectrum of the respective mite species. To our knowledge no information is accessible on the comparison between natural diets and factitious prey for Amblyseius swirskii Athias-Henriot. Therefore, the objective of this study was to evaluate the nutritional value of three natural diets including almond pollen, maize pollen and Tetranychus urticae Koch, as well as four factitious prey comprising eggs of Ephestia kuehniella Zeller, Tyrophagus putrescentiae (Schrank), decapsulated and encapsulated cysts of Artemia franciscana Leach for A. swirskii. The data would seem to suggest that developmental time of individuals fed on pollens was shorter than that of those fed on factitious prey. The gross and net reproductive rate, intrinsic and finite rate of increase of the individuals consumed factitious prey were lower than those of mites fed on natural food diets, for the simple reason of shorter developmental time and higher oviposition rate of this predator on the latter. In conclusion, our results showed that natural foods were more favorable than factitious prey and among them almond pollen and maize pollen were the most suitable for A. swirskii, and thus it should be taken into account for application in its mass production, and supporting its population in greenhouse or field conditions when used in an augmentative approach.

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is a well-known pest mite with an extensive host range worldwide. The control of T. urticae populations mostly relies on the application of synthetic acaricides or pesticides. Chlorfenapyr is a broad spectrum insecticide/miticide effective against agriculturally important pests. In this study, sublethal effects (LC10, LC20 and LC30) of this insecticide on demographic parameters of T. urticae based on the age-stage, two-sex life table theory were investigated under laboratory conditions [25 ± 2 °C, 60 ± 5 % RH and 16:8 (L:D) h]. According to the obtained results, the LC50 value for females of T. urticae was 47.66 ppm. The egg incubation, protonymph, as well as deutonymph durations of both sexes were significantly reduced as a consequence of treatment with LC20 and LC30 of chlorfenapyr. In addition, our results indicated that oviposition period in LC10 lasted 9.62 days, which was closer to the control (9.73 days); while it significantly decreased with increasing the concentration from LC20 to LC30. Furthermore, LC20 and LC30 treatments decreased the fecundity of females by 55.5% and 61.6%, respectively. The values of both intrinsic (r) and finite rates of increase (λ) at LC20 and LC30 was significantly inferior to other experimental treatments. It could be concluded that along with the lethal doses, the sublethal concentrations of chlorfenapyr profoundly reduced the population growth rate of T. urticae.

AbstractDiet is a critical component of the mass-rearing of biological control agents, but the impacts of diet are not always immediately obvious and can take several generations to manifest, resulting in poor survival, reproduction, and ability to kill prey under natural conditions. Our present study aimed to investigate the performance of a commercially-reared phytoseiid mite, Amblyseius swirskii, after four (G4) and six (G6) consecutive generations on pollen grains of two plant species, as well as its ability to find and kill its natural prey, Tetranychus urticae, after long-term rearing on each diet. We found no significant difference between the two diets in intrinsic and finite rates in G4. However, both diet and generation exerted a significant influence on the fecundity of A. swirskii. By G6, females reared on almond pollen had greater net reproductive and intrinsic rate compared to those reared on maize pollen. Conversely, A. swirskii fed on maize pollen consumed fewer prey than those reared on other diets, especially at higher prey densities. The findings have important implications for developing the mass-rearing program of A. swirskii on non-prey diets. Further research must explore the suitability of almond pollen in the large-scale culture of A. swirskii.

Background Using alternative diets for the mass production of phytoseiid predatory mites may facilitate their cost-effective rearing. Factitious prey is often used as an alternative food source for mass rearing of generalist phytoseiids. The generalist predator, Neoseiulus cucumeris (Oudemans), is a commercially available biocontrol agent against various pests. We assessed the suitability of two factitious prey, Ephestia kuehniella Zeller eggs and Tyrophagus putrescentiae (Schrank), as diets for long-term rearing (up to 30 generations) of N. cucumeris, when compared with a natural prey, Tetranychus urticae Koch. Results The predator completed its development on all tested diets successfully. Under laboratory conditions, Tyrophagus putrescentiae could support the development and oviposition of the predator for up to 30 generations even better than its natural prey T. urticae. However, the eggs of E. kuehniella were not suitable for this predator because of the longer pre-adult period and adults failed to reproduce. Conclusions Since rearing on T. putrescentiae for a long time had no adverse effects on the predator’s performance, this factitious prey could be considered as a suitable and cost-effective diet for mass production of N. cucumeris.