The potential of highly nutritious frozen stages of Tyrophagus putrescentiae as a supplemental food source for the predatory mite Amblyseius swirskii

Astigmatid mites have potential as supplementary prey items to support generalist predator populations in crops. However, applying living prey mites has some disadvantages; if not predated they have the potential to cause crop damage and allergies. In this study, we evaluated various diets based on the astigmatid mite Tyrophagous putrescentiae (Schrank) as a supplemental food source for the predatory mite Amblyseius swirskii Ahias-Henriot. Eggs and larvae of T. putrescentiae were reared on a diet of dog food (rich in proteins and fat) or bran (rich in carbohydrate); they were offered either frozen or alive, and either with or without cattail pollen (Typha angustifolia L.). Oviposition rate of A. swirskii fed with frozen mite larvae reared on dog food was similar to the rate observed when they were fed with cattail pollen or living prey mites, but developmental time of A. swirskii was longer on this frozen diet than on a diet of living prey mites or pollen. Both living and frozen prey mites were, in contrast with cattail pollen, not suitable for oviposition by western flower thrips, Frankliniella occidentalis Pergande. In a greenhouse study, the use of frozen prey mite stages as supplemental food on chrysanthemum plants allowed populations of A. swirskii to establish, but not increase; in contrast, provision of living prey mites and pollen increased A. swirskii populations on plants. Hence, our study shows that living prey mites, but not frozen prey mites, had the greatest potential as a supplemental food source for A. swirskii.</p

Active and frozen host mite Tyrophagus putrescentiae (Acari : Acaridae) influence the mass production of the predatory mite Blattisocius mali (Acari: Blattisociidae): life table analysis

Blattisocius mali (Oudemans) is a candidate predatory mite on some astigmatid mite pests like Tyrophagus putrescentiae (Schrank). In current study, life table parameters of B. mali were comparatively evaluated when fed on mixed life stages, frozen (one day at-20°C) and cold stored (90 days at-20°C and 4°C) eggs of T. putrescentiae. The highest and lowest values of fecundity, total longevity, oviposition period, life span and adult longevity of B. mali were observed when the predator provided with one-day and 90-days frozen eggs (stored at 4°C) of T. putrescentiae, respectively. Moreover, the highest values of net reproductive rate (R0), intrinsic rate of increase (r) and finite rate of increase (λ) of B. mali were obtained by feeding on one-day frozen eggs (23.94 offspring/individual, 0.332 day-1, 1.39 day-1, respectively), without significant differences from the predators reared on alive mixed stages of T. putrescentiae. However, the lowest values of R0 (1.54 offspring/individual), r (0.058 day-1) and λ (1.06 day-1) were recorded when B. mali was reared on 90-days frozen eggs (stored at 4°C). The results, as first evidence of life-history of B. mali, represent not only the potential of the predator as suitable biological control agent against T. putrescentiae, but also the possibility of its mass production by frozen host stages. Provision of one-day frozen eggs of T. putrescentiae were the best choice for B. mali survival and reproduction with no harmful effects of living stages (direct damage, frass and exuviae) on crop