Influence of pollen feeding on body weight and body size of the predatory mite Amblyseius swirskii (Acari, Phytoseiidae)

Abstract

The nutritional quality of pollen was assessed measuring biomass and body size of freshly emerged, 1, 3, and 30 day old adult Amblyseius swirskii continuously reared on pollen of Betula pendula, Helianthus annuus, Paulownia tomentosa, and Zea mays.

Body weight of females was significantly higher than that of males, irrespectively both, the pollen fed and the age class. Weight of freshly emerged females was significantly superior when fed with pollen of P. tomentosa and Z. mays compared to those fed with B. pendula or H. annuus pollen. Biomass of females significantly increased until the age of 3 days, then remaining constant or decreasing until the age of 30 days. Weight gain with ageing is explained by higher food uptake by females for egg production and egg maturation. Weight gain of males also reached its maximum at day 3 of adult life, then decreasing until day 30. Congruent with biomass, adult body length and width differed significantly between sex and age showing females bigger than males and 30 day old adults bigger than 1 day old adults irrespectively the pollen fed. Both the parameters were affected by pollen, revealing P. tomentosa as best food source, followed by Z. mays and B. pendula. No reasonable correlation was found between body length and width, but body weight was significantly correlated with body length in females whereas there was no correlation at all in males.