Deguenon Jean M, Dhammi Anirudh, Ponnusamy Loganathan, Travanty Nicholas V, Cave Grayson, Lawrie Roger, Mott Dan, Reisig Dominic, Kurtz Ryan, Roe R Michael
Department of Entomology and Plant Pathology, North Carolina State University, 3230 Ligon Street, Campus Box 7647, Raleigh, NC 27695-7647, USA.
Cotton Incorporated, Cary, NC 27513, USA.
Microorganisms. 2021 Apr 20;9(4):878. doi: 10.3390/microorganisms9040878.
The bollworm, (Boddie) (Lepidoptera: Noctuidae), is an important agricultural pest in U.S. cotton and is managed using transgenic hybrids that produce insecticidal proteins from the bacterium, (Bt). The reduced efficacy against caterpillars of Bt plants expressing Cry toxins is increasing in the field. In a first step towards understanding Bt cotton-bollworm-microbiota interactions, we investigated the internal bacterial microbiota of second-third stadium collected in the field from non-Bt versus Bt (WideStrike) cotton in close proximity (in North Carolina, USA). The bacterial populations were analyzed using culture-dependent and -independent molecular approaches. We found that WideStrike samples had a higher bacterial density and diversity per larva than insects collected from non-Bt cotton over two field seasons: 8.42 ± 0.23 and 5.36 ± 0.75 (log colony forming units per insect) for WideStrike compared to 6.82 ± 0.20 and 4.30 ± 0.56 for non-Bt cotton for seasons 1 and 2, respectively. Fifteen phyla, 103 families, and 229 genera were identified after performing Illumina sequencing of the 16S rRNA. At the family level, Enterobacteriaceae and Enterococcaceae were the most abundant taxa. The Enterococcaceae family was comprised mostly of Enterococcus species ( and another sp.). Members of the genus can acidify their environment and can potentially reduce the alkaline activation of some Bt toxins. These findings argue for more research to better understand the role of cotton-bollworm-bacteria interactions and the impact on Bt toxin caterpillar susceptibility.
棉铃虫（Boddie）（鳞翅目：夜蛾科）是美国棉花种植中的一种重要农业害虫，目前通过种植能产生来自苏云金芽孢杆菌（Bt）杀虫蛋白的转基因杂交品种来进行防治。在田间，表达Cry毒素的Bt棉花对棉铃虫幼虫的防治效果正在下降。为了初步了解Bt棉花-棉铃虫-微生物群之间的相互作用，我们在美国北卡罗来纳州对紧邻种植的非Bt棉花和Bt（WideStrike）棉花上采集的二至三龄棉铃虫的体内细菌微生物群进行了调查。使用依赖培养和不依赖培养的分子方法对细菌种群进行了分析。我们发现，在两个田间季节中，与从非Bt棉花上采集的昆虫相比，从WideStrike样本中采集的每只幼虫的细菌密度和多样性更高：第一季和第二季中，WideStrike样本的细菌密度分别为8.42±0.23和5.36±0.75（每只昆虫的对数菌落形成单位），而非Bt棉花的细菌密度分别为6.82±0.20和4.30±0.56。在对16S rRNA进行Illumina测序后，鉴定出了15个门、103个科和229个属。在科水平上，肠杆菌科和肠球菌科是最丰富的分类群。肠球菌科主要由肠球菌属物种（和另一个种）组成。肠球菌属的成员可以酸化其生存环境，并可能降低某些Bt毒素的碱性激活。这些发现表明需要进行更多研究，以更好地了解棉花-棉铃虫-细菌相互作用的作用以及对Bt毒素对毛毛虫易感性的影响。
