Habitat influences on diversity of bacteria found on German cockroach in Beijing

Cockroaches are worldwide indoor pests carrying microorganisms of medical importance.German cockroaches (Blattella germanica) were sampled in five habitats (hospital, restaurant, office home, and market) in Beijing, and the bacteria were isolated from their external surface and alimentary tract and identified using a Biolog identification system.Cockroach densities significantly differed among habitats (market > home > office > restaurant > hospital).However, no significant differences in bacterial abundance carried by individual German cockroaches (of either sex) were found among habitats.The bacterial abundance in the gut was significantly higher than that on the surface.There were no significant differences in bacterial species richness observed among habitats, sex, carrying position or their interaction.Cluster analysis showed that cockroach densities and bacterial abundance found in the market differed significantly from the other four habitats.The bacterial diversity was not significantly reduced in sensitive facilities such as hospital and restaurant, even though pesticide and bactericide were more frequently applied there.The implications of these findings were discussed in this article.     

久效磷对细小色矛线虫胚胎发育和繁殖的影响

采用平板静态毒性实验方法,研究了久效磷对细小色矛线虫(Chromadorina germanica)的急性毒性及胚胎发育和繁殖的影响,并探讨了其毒性作用机制.结果表明,久效磷对C. germanica 的24,48,96h的LC50分别为66.42,36.94,16.03 μmol/L.对C. germanica繁殖具有显著的抑制作用:1.0μmol/L久效磷暴露组子一代的数量急剧减少,仅为对照组的52.9%,10μmol/L暴露组则完全抑制了产卵和子一代的产生.对C.germanica的胚胎毒性主要表现为胚胎发育时间的延迟:0.1,1.0,10.0μmol/L久效磷暴露组胚胎发育持续时间比对照组的17.05h分别延长了1.24,1.92,1.96h,呈剂量-效应关系,且10.0μmol/L久效磷完全抑制了卵的孵化.久效磷对C. germanica精巢和卵巢超微结构的损伤,导致了精子和卵子质量下降.因此,久效磷导致C.germanica的胚胎发育持续时间的延长和精子、卵子质量下降是其子一代数量急剧减少的主要原因之一.