Armstrong J L, Porteous L A, Wood N D
Terrestrial Microbial Ecology/Biotechnology Program, U.S. Environmental Protection Agency, Corvallis, Oregon 97333.
Appl Environ Microbiol. 1989 Sep;55(9):2200-5. doi: 10.1128/aem.55.9.2200-2205.1989.
Variegated cutworms were exposed to bean plants in microcosms sprayed with pBR322-carrying strains of Enterobacter cloacae, Klebsiella planticola, and Erwinia herbicola. The three bacterial species exhibited differential survival on leaves, in soil, and in guts and fecal pellets (frass) of the insects. High numbers of Enterobacter cloacae(pBR322) were detected in all samples, while the other species were unable to establish residence in the insect. To assess the impact of this colonization on site-to-site transport of microorganisms, larvae were fed plants that had been sprayed with the bacteria and then were transferred to uninoculated plants. Cutworms were efficient carriers of Enterobacter cloacae(pBR322), as indicated by its rapid appearance on uninoculated leaves and continued persistence in the insects for 3 days after transfer. Few Erwinia herbicola(pBR322) and K. planticola(pBR322) were obtained from larvae after transfer, although up to 10(3) CFU/g were detected in soil and on plants. Differences in bacterial survival and growth were confirmed by incubating frass overnight and observing the change in population numbers. The proportion of total samples showing at least a 25-fold increase during incubation was 68% for Enterobacter cloacae(pBR322), 39% for K. planticola(pBR322), and 0% for Erwinia herbicola(pBR322). Our results emphasize the role that cutworms and possibly other insects have in persistence and growth of microorganisms in the environment.
将杂色夜蛾暴露于种植在微观环境中的菜豆植株上，这些微观环境已喷洒了携带pBR322的阴沟肠杆菌、栖稻假单胞菌和草生欧文氏菌菌株。这三种细菌在叶片、土壤以及昆虫的肠道和粪便颗粒（粪粒）中表现出不同的存活情况。在所有样本中均检测到大量的阴沟肠杆菌（pBR322），而其他菌种无法在昆虫体内定殖。为了评估这种定殖对微生物在不同地点间传播的影响，给幼虫喂食已喷洒细菌的植株，然后将其转移到未接种的植株上。杂色夜蛾是阴沟肠杆菌（pBR322）的有效携带者，这表现为该菌迅速出现在未接种的叶片上，并在转移后在昆虫体内持续存在3天。转移后从幼虫中获得的草生欧文氏菌（pBR322）和栖稻假单胞菌（pBR322）很少，尽管在土壤和植株上检测到高达10³CFU/g。通过将粪粒过夜培养并观察菌数变化，证实了细菌存活和生长的差异。在培养过程中菌数至少增加25倍的总样本比例，阴沟肠杆菌（pBR322）为68%，栖稻假单胞菌（pBR322）为39%，草生欧文氏菌（pBR322）为0%。我们的结果强调了杂色夜蛾以及可能其他昆虫在环境中微生物的持久性和生长方面所起的作用。
