Chronic lead exposure prolongs the immature stages of brown-legged grain mite, Aleuroglyphus ovatus, in a long-term population study.

ABSTRACT

An important aspect of environmental pollution, lead contamination is a widespread problem in several ecosystems. The present study aimed to evaluate the potential effects of low concentration lead stress on the development and reproduction of Aleuroglyphus ovatus. They were fed with artificial diet containing four different concentrations of lead (12.5, 25, 50, and 100 mg/kg). The results showed that there were both accelerating effect of lead (at low concentrations), as well as retarding effects (at high concentrations) on the development of the mite, and lead stress significantly prolonged the immature stages of A. ovatus and this inhibitory effect was greater with greater lead concentrations. The immature stages in the L group were shorter than those in the S group. In the S and L groups, the oviposition periods were significantly longer in the treatments with lower lead concentrations than in the control, while they were significantly shorter in those treatments of higher lead concentrations. Age-specific survival rate (lx) started to decline earlier in the S group, whereas there were no differences between the L group and CK. Age-specific fecundity rate (mx) peaked earlier in the S group than in CK, while mx peaked later in L1 and L2 than in CK. The rm value and net reproduction rate (R0) of treated A. ovatus decreased with increasing lead concentrations. Lower lead concentrations could promote population expansion while higher concentrations could inhibit population size. These results confirmed the developmental effect of lead stress on A. ovatus, highlighting that heavy metal contamination has negative effects on organisms in their natural environment.