Different breeding conditions affect the morphological variability in larvae of Platytrombidium fasciatum (Trombidiformes: Microtrombidiidae)

Abstract

The impact of temperature and light/dark cycle on morphological traits of Platytrombidium fasciatum was examined in larvae obtained from field-collected females. The eggs laid by 65 females at laboratory conditions were assigned to four experimental groups. Varied thermal conditions affected the values of nine out of 46 (nonparametric MANOVA) and 26 out of 37 (LDA) morphometric traits in larvae. As many as six quantitative traits differed significantly irrespective of the method (MANOVA, LDA) applied. The analysis of the metric traits within the dorsal sclerites revealed that the lower mean temperature over the period of egg incubation, translated into longer duration of development, was associated with an increase in distance between the bases of 3rd pair of non-sensillary setae on scutum at the decrease in distance between the bases of 2nd pair of non-sensillary setae as well as in distance between the level of sensilla and the posterior edge of the sclerite. In the case of 40 measurable traits in larvae of P. fasciatum, the variability going beyond the hitherto knowledge on the species was observed.