Responses Of Flesh Fly (Boettcherisca Peregrina) To Heavy Metals And Its Adaptation Mechanism

There is a growing public concern over the potential pollution of heavy metals in China owing to rapid urban and industrial development in the last several decades. Heavy metals are nonbiodegradable and they can be accumulated by organisms and have adverse effects at different levels of organization, such as population, individual organisms, tissues and cells. These effects are demonstrated in life-history traits of an organisms, for example, development, growth, aging, longevity, survival and reproduction. In the ecosystems insects (such as flies, mosquitoes, beetles and ants) play an important role in the transport and reintegration of heavy metals, and the insects have developed special adaptation mechanism to resist the heavy metal under the metal-pollution stress. Thus, it is of the utmost importance to investigate heavy metal accumulation in such insects, effects on the insects and adaptation mechanism of the insects. In this paper, the accumulation, the responses, homeostasis and storage mechanism of flesh fly (Biettcherisca peregrina) to Cd²⁺ and Cu²⁺ are studied. The results are shown as follows:1 Effects of Cd²⁺ and Cu²⁺ on development and reproduction of parental generation (P) and filial generation (F₁) of Biettcherisca peregrinaThe development and reproduction of P generation and F₁ generation of B. peregrina were studied after newly oviposited larvae of P generation were exposed to various concentrations of Cd²⁺ or Cu²⁺ administered in the artificial diet until pupation. The duration of the larval stages and pupal stages in P generation increased in proportion to the concentrations of metal ion, but the adult lives of treated-group got shortened than control group. The weight of larvae, pupae and newly emerged adults in P generation of treated-group decreased with Cd²⁺ or Cu²⁺ concentration. In addition, the body length of larvae and pupae in P generation of treated-group decreased with Cd²⁺ or Cu²⁺ concentration too. Survival of larvae, pupae and adult in P generation of treated-group was decreased with metal concentration. Although the sex ratio of adult comingfrom the larvae exposed to Cd²⁺ or Cu²⁺ had no significance compared with the control, mating rate of male and female were significantly lower than controls. Fecundity of females of treated groups was also significantly reduced. However, all above parameters of F1 generation coming from parents exposed to Cd²⁺ or Cu²⁺ and controls were not significantly different. These results show that development and reproduction of P generation are seriously impaired at sublethal Cd²⁺ or Cu²⁺ concentrations, but the impairment of P generation induced by Cd²⁺ or Cu²⁺ don't influence the development and reproduction of the offspring. Moreover, low concentrations of heavy metals affected little to the development of B. peregrina and have stimulatory function to some extent, implying that B. peregrina has good mechanism to regulate metals.2 Accumulation and excretion of Cd²⁺ and Cu²⁺ in Biettcherisca peregrina larvaeB. peregrina larvae fed on food supplemented with Cd²⁺ retained most of ingested Cd²⁺. Few ingested Cd²⁺ were excreted by excretory system. Cd²⁺ accumulation in larvae of B. peregrina was proportional to treatment time, but not to Cd + concentration in food. Especially, Cd²⁺ accumulation and excretion in larvae both decreased at more than 200 u g/g Cd²⁺ exposure than 200 μg/g exposure. This maybe ascribe to toxic effect of Cd²⁺ on larvae. During metamorphosis, the loss of Cd²⁺ took place almost entirely at pupation. Newly eclosion adults had lower Cd²⁺ concents than the larvae. This loss of Cd²⁺ was correlated to the excretion of Cd²⁺.B. peregrina larvae fed on food supplemented with Cu²⁺ retained about half amounts of ingested Cu²⁺. Few ingested Cu²⁺ were excreted by excretory system. Cu²⁺ accumulation and excretion in larvae of B. peregrina were proportional to treatment time and to Cu²⁺ concentration in food. During metamorphosis, Cu²⁺ w...