Bioaccumulation And Bioamplification Of Toxic Organic Pollutants In Lepidoptera Insects During Metamorphosis

Toxic organic pollutants(TOPs),such as polycyclic aromatic hydrocarbons(PAHs),polychlorinated biphenyls(PCBs),polybrominated diphenyl ethers(PBDEs)are ubiquitous contaminants in the environment.Halogenated organic pollutants(HOPs),such as PCBs,have attracted attention because of their persistence,long-range transport and potential health risks to the environment and humans.HOPs can bioaccumulate in organisms and biomagnify through food chains.PAHs are one of the most concerned environmental pollutants due to their wide distribution,high concentration,and carcinogenicity in the environment.Insects are the integral and important components of the ecosystem due to their ubiquity and quantity.Metamorphosis often results in in drastic changes in morphology,chemistry,and habitat as insects develop from larvae to adults.During metamorphosis,insects alter substantial energy and contaminants fluxes through linking food webs in different habitats and niches.The alteration of HOPs concentration and composition in insects during metamorphosis have been reported.Previous studies have revealed that the regulatory mechanism of HOPs in insects during metamorphosis is common to the insects.At present,most studies are focused on the bioaccumulation of metals,PCBs and PAHs in aquatic insects,more studies about novel HOPs are necessary.Meanwhile,the effects of metamorphosis on pollutions are still less studied.A broad suite of TOPs,including PAHs,PCBs,PBDEs,dechlorane plus(DP),decabromodiphenyl ethane(DBDPE)and hexabromocyclododecane(HBCD)were investigated in the present thesis.Firstly,a partial life cycle test was performed with fourth instar larvae(Lepidoptera,Bombyx mori)exposed to different levels of TOPs.Secondly,lepidoptera terrestrial insects were collected from an e-waste recycling site in Qingyuan County,Guangdong Province.The aims were to investigate the accumulation of these organic pollutants in lepidopteran insects and the regulation of these pollutants in the process of metamorphosis.The adverse effects of pollutants exposure on the growth and development of silkworms were researched and the maternal transfer of TOPs between female moth and eggs were investigated.Contaminants exposures resulted in decreased body weights,increased development times,and reductions of fecundity in silkworms.These adverse effects were partly related to the exposure level.Assimilation efficiencies of TOPs decreased with increasing octanol-water partition coefficients(log K_OW).Larval silkworms showed selective enrichment of isomers and chiral compounds;however,there was no selective enrichment of chiral compounds across metamorphosis.However,the f_antivalue and EF value of?-HBCD of oviposition female moth was significantly different from others,indicating that there may be selective transfer during the oviposition.From silkworm larvae to pupae,the relationship between the bioamplification factors(BAmFs)of HOPs and log K_OWwas dose-dependent.The BAmFs of high-dose was significantly positive with log K_OW,while no significant trend was found in low-dose group.During pupation and reproduction,the relationship between BAmFs and log K_OW showed gender specific.During pupation,the BAmFs of female moths were parabolically related to log K_OW.When log K_OW<7.5,BAm F increased,and then BAmFs decreased with log K_OW.The BAmFs of male moths were negatively correlated with log K_OW.Before and after reproduction,BAmFs was positively correlated with log K_OW for females after oviposition,while BAmFs of male moths showed no correlation with the log K_OW.The reason for the gender-specific may be related to the difference in metabolism between female and male moths during metamorphosis and the difference in intergenerational transfer during reproduction.PAHs were the predominant contaminants in insects collected in the e-waste recycling site,followed by PCBs.The composition of PCBs and other pollutants in the three types of insects has certain differences among species,which may be caused by differences in habitat,feeding habits and enrichment capacity.The BMF values of PCBs,PBDEs and DBDPE in noctuid were all greater than 1,showing biomagnification capacity;while the BMF value of PAHs was less than 1,showing no biomagnification capacity.The log BMFs of HOPs and PAHs in noctuid were negatively correlated with their log K_OW.From larvae to pupae in noctuid,BAmFs of HOPs were linearly positively correlated with log K_OW,which was consistent with the trends of silkworm.From pupa to moth,the relationship between BAmFs and log K_OW was parabolic.When log K_OW<8,BAm F increased as log K_OW increased,and then BAmFs decreased as log K_OWincreased.The enrichment behavior of PAHs during metamorphosis in noctuid was different from that of HOPs.During the pupation process,the BAmFs of PAHs was not related to log K_OW;during the emergence process,the BAmFs of PAHs had a parabolic relationship with log K_OW.During the emergence,the trend of BAmFs did not show gender specific.