Vitamin A is essential for photoperiodic induction of diapause in an eyeless mite

Abstract

The perception of photoperiod by insects and mites requires a photoreceptor which is probably located in the brain^1–5. Recently, the functional involvement of carotenoids in the photoperiodic reaction of two mite species has been demonstrated using techniques based on mutant studies and nutritional studies respectively^6–8. In dietary studies with insects, evidence for the participation of carotenoids in the photoperiodic induction of diapause has been found in one moth species⁹, whereas carotenoid deprivation has no effect in another moth¹⁰ and a butterfly¹¹. Here we show that vitamin A as well as carotenoids with provitamin A function, but not vitamin A acid, restores the photoperiodic reaction in an eyeless predacious mite which has lost all sensitivity to the photoperiod after having been reared for more than one generation on pollen of broad bean, which constitutes a completely carotenoid-free diet. This study suggests that a rhodopsin-like pigment functions as the photoreceptor for the photoperiodic induction of diapause in these mites.