Influence of construction and demolition waste on fitness and community structure of cicada nymphs: New bioindicators of soil pollution

Construction and demolition (C&D) waste is a novel, widespread environmental stress that negatively affects environment, organisms and ecosystem. Yet effects of cumulative consequences of C&D waste on the fitness and community structure of most underground insects remain unclear. With relatively sessile life underground lasting several years, cicadas can be an important aspect in forest nutrient cycles. Whether cicada nymphs are easily affected by C&D waste, and whether they have evolved any adaptations to cope with the adverse environments merit exploration. Here, we investigated the biodiversity, community structure, population dynamics and morphology of cicada nymphs in both uncontaminated and contaminated habitats by C&D waste in Guanzhong Plain, China since 2011. In total, 1,573 cicada nymphs were collected from 2011 to 2015, including 62 malformed nymphs. The malformed nymphs can be divided into three types: physically damaged individuals (still alive) (3.2%), fungus-infected individuals (dead) (64.5%), and bacterium-infected individuals (dead) (32.3%). The proportion of malformed nymphs increased year by year in the habitats contaminated by C&D waste. In the uncontaminated habitats, although no significant differences of population density among the investigated years were observed, yet there was a distinct increasing trend of population of Meimuna mongolica, whereas populations of both Cryptotympana atrata and Platypleura kaempferi distinctly decreased. This indicates that M. mongolica is possibly evolving into the most dominant species in the ecological niche when it competes with other sympatric species, but more researches are needed to establish whether there is a shift in the species composition of cicadas. In the habitats contaminated by C&D waste, a higher ratio of malformed individuals and a decline of population of both M. mongolica and C. atrata were revealed; P. kaempferi was not found in the contaminated habitats, indicating a weaker resistance of this species against C&D waste. The negative responses of cicada nymphs to C&D waste have significant implications for the habitat destruction. Cicada nymphs may be suitable bioindicators for underground-habitat-quality monitoring, as merits further research to reveal the association between the magnitude of C&D waste contamination with the fitness and population dynamics of cicada nymphs.