Development, survival and reproduction of a New Zealand strain of Amblydromalus limonicus (Acari: Phytoseiidae) on Typha orientalis pollen, Ephestia kuehniella eggs, and an artificial diet

Abstract

ABSTRACTThe performance of a New Zealand strain of the generalist predatory mite Amblydromalus limonicus (Garman & McGregor) (Acari: Phytoseiidae) on factitious and artificial diets was evaluated in the laboratory at 25 ± 1°C. In experiment 1, A. limonicus individuals were reared in enclosed cells without access to water in a room with an ambient relative humidity of 50% on the following diets: Typha orientalis pollen; Ephestia kuehniella Zeller eggs (Lepidoptera: Pyralidae), either untreated, punctured or coated with bee honey solution (10%); and an artificial diet enriched with the pupal haemolymph of Epiphyas posvittana (Lepidoptera: Tortricidae). The egg-to-adult survival rate and that at each immature stage of A. limonicus were significantly influenced by diet, except for the eggs. About 66%, 56.8% and 52.9% of individuals developed to adulthood when fed on T. orientalis pollen, artificial diet and E. kuehniella-punctured, respectively. None of the A. limonicus individuals completed the deutonymphal stage when only 10% bee honey solution was provided, and most immature mites were unable to puncture intact E. kuehniella eggs, which were hardened by low ambient humidity (50%). However, coating E. kuehniella eggs with 10% bee honey solution reduced hardening of the eggs and resulted in more than a sixfold increase in total immature survival (compared to no coating). A. limonicus immatures had higher survival rates and developed faster, and adult females deposited more eggs, when fed on T. orientalis pollen compared to artificial diet. In experiment 2, developmental time and survival of immature A. limonicus on E. kuehniella eggs were compared under 50% or 90% relative humidity, with or without access to water (via punctured leaf in the cell). Ambient relative humidity influenced the larva, protonymph and total immature survival of A. limonicus when fed on E. kuehniella eggs: egg-to-adult survival rates reached 78.6% and 76.9% when the predatory mites had access to water or the ambient relative humidity was 90%. In conclusion, T. orientalis pollen and E. kuehniella eggs (to a lesser extent) will be suitable food sources for the augmentation of A. limonicus and can also be used as alternative diets for preventive releases in early crop seasons.