Alternative pollen diets modulate cannibalism in two phytoseiid mites (Neoseiulus agrestis and Neoseiulus barkeri)

Cannibalism is common in phytoseiid mites. It helps predators survive during food scarcity but may affect their sustainability for pest control in agricultural systems. Neoseiulus agrestis (Karg) and Neoseiulus barkeri Hughes (Acari: Phytoseiidae), found in Inner Mongolia, show potential for controlling spider mites. It is currently unclear the impact of food availability on the frequency of cannibalism in these two species. Pollen is an important alternative food source for generalist predatory mites. This study investigated how starvation durations (0, 12, and 24 h) of cannibals and pollen diets (Typha sp. and Zea mays L.) affect the cannibalism rate in N. agrestis and N. barkeri. Results showed that only adults of both species preyed on juvenile conspecifics, with N. agrestis exhibiting most aggressive toward conspecific nymphs and N. barkeri exhibiting most aggressive toward conspecific larvae. The prolonged starvation duration of cannibals significantly increased cannibalism rates in both species of predatory mites. Meanwhile, adding cattail pollen significantly increased conspecific survival and reduced cannibalism, but this effect was observed only in N. agrestis, not in N. barkeri. Adding maize pollen significantly increased conspecific survival and reduced cannibalism in both predators. This suggests that the occurrence of cannibalism varied across phytoseiid species, developmental stages, starvation durations, and pollen species. Furthermore, maize pollen reduced cannibalism in both predators, which may help manage spider mites on maize at low population levels.