The Effect of Different Heavy Metals on the Development of Lucilia sericata (Diptera: Calliphoridae)

Klebsiella pneumoniae in the intestines of Musca domestica larvae can assist the host in antagonizing the poisoning of the heavy metal copper

BACKGROUND

Musca domestica larvae are common saprophytes in nature, promoting the material-energy cycle in the environment. However, heavy metal pollution in the environment negatively affects their function in material circulation. Our previous research found that some intestinal bacteria play an important role in the development of housefly, but the responses of microbial community to heavy metal stresses in Musca domestica is less studied.

RESULTS

In this study, CuSO4, CuSO4-Klebsiella pneumoniae mixture and CuSO4-K. pneumoniae phage mixture were added to the larval diet to analyze whether K. pneumoniae can protect housefly larvae against Cu2+ injury. Our results showed that larval development was inhibited when were fed with CuSO4, the bacterial abundance of Providencia in the intestine of larvae increased. However, the inhibition effects of CuSO4 was relieved when K. pneumoniae mixed and added in larval diets, the abundance of Providencia decreased. Electron microscope results revealed that K. pneumoniae showed an obvious adsorption effect on copper ion in vitro.

CONCLUSIONS

Based on the results we assume that K. pneumoniae could adsorb Cu2+, reduce Cu2+ impact on gut community structure. Our study explains the role of K. pneumoniae antagonizing Cu2+, which could be applied as a probiotic to saprophytic bioantagonistic metal contamination.

How Rearing Systems for Various Species of Flies Benefit Humanity

Flies (Diptera) have played a prominent role in human history, and several fly species are reared at different scales and for different beneficial purposes worldwide. Here, we review the historical importance of fly rearing as a foundation for insect rearing science and technology and synthesize information on the uses and rearing diets of more than 50 fly species in the families Asilidae, Calliphoridae, Coelopidae, Drosophilidae, Ephydridae, Muscidae, Sarcophagidae, Stratiomyidae, Syrphidae, Tachinidae, Tephritidae, and Tipulidae. We report more than 10 uses and applications of reared flies to the well-being and progress of humanity. We focus on the fields of animal feed and human food products, pest control and pollination services, medical wound therapy treatments, criminal investigations, and on the development of several branches of biology using flies as model organisms. We highlight the relevance of laboratory-reared Drosophila melanogaster Meigen as a vehicle of great scientific discoveries that have shaped our understanding of many biological systems, including the genetic basis of heredity and of terrible diseases such as cancer. We point out key areas of fly-rearing research such as nutrition, physiology, anatomy/morphology, genetics, genetic pest management, cryopreservation, and ecology. We conclude that fly rearing is an activity with great benefits for human well-being and should be promoted for future advancement in diverse and innovative methods of improving existing and emerging problems to humanity.

The susceptibility of Hyphantria cunea larvae to microbial pesticides Bacillus thuringiensis and Mamestra brassicae nuclear polyhedrosis virus under Cd stress

Heavy metal pollution is an abiotic factor that can affect the efficiency of pest control. In this study, two microbial pesticides, Bacillus thuringiensis and Mamestra brassicae nuclear polyhedrosis virus (MbNPV), were used to treat Hyphantria cunea larvae with Cd pre-exposure, and the humoral and cellular immunity of H. cunea larvae with Cd exposure were evaluated. The results showed that Cd exposure increased the susceptibility of H. cunea larvae to microbial pesticides B. thuringiensis and MbNPV, and the lethal effect of Cd exposure and microbial pesticides on H. cunea larvae was synergistic. Cd exposure significantly decreased the expression of pathogen recognition genes (GNBP1 and GNBP3), signal transduction genes (Relish, Myd88, Tube, and Imd), and antimicrobial peptide gene (Lebocin) in the humoral immunity of H. cunea larvae compared with the untreated larvae. Parameters of cellular immunity, including the number of hemocytes, phagocytic activity, melanization activity, encapsulation activity, and the expression of three phagocytic regulatory genes (HEM1, GALE1, GALE2), were also found to decrease significantly in Cd-treated larvae. TOPSIS analysis showed that humoral immunity, cellular immunity, and total immunity levels of H. cunea larvae with Cd exposure were weaker than those in untreated larvae. Correlation analysis showed that the mortality of two microbial pesticides investigated in H. cunea larvae was negatively correlated with the humoral and cellular immunity of larvae. Taken togther, Cd exposure results in immunotoxic effects on H. cunea larvae and the use of microbial pesticides are an effective strategy for pest control in heavy metal-polluted areas.