van der Merwe Marcel, Jukes Michael D, Knox Caroline, Moore Sean D, Hill Martin P
Department of Biochemistry and Microbiology, Rhodes University, P.O. Box 94, Makhanda 6140, South Africa.
Centre for Biological Control, Department of Zoology and Entomology, Rhodes University, P.O. Box 94, Makhanda 6140, South Africa.
Insects. 2022 Feb 28;13(3):243. doi: 10.3390/insects13030243.
Thaumatotibia leucotreta is endemic to southern Africa and is highly significant for various fruit industries, including the South African citrus industry, due to its classification as a phytosanitary pest. Mutualistic associations between C. pomonella, closely related to T. leucotreta, and yeasts have previously been described and reported to reduce larval mortality and enhance larval development. Here, we determined which yeast species occur naturally in the gut of T. leucotreta larvae and investigated whether any of the isolated yeast species affect their behaviour and development. Navel oranges infested with T. leucotreta larvae were collected from geographically distinct provinces in South Africa, and the larvae were processed for analysis of naturally occurring associated yeasts. Six yeast species were isolated and identified from the guts of these T. leucotreta larvae via PCR amplification and sequencing of the ITS region of rDNA and D1/D2 domain of large ribosomal subunit. Larval development and attraction assays were conducted, and T. leucotreta larvae that fed on Navel oranges inoculated with yeast had accelerated developmental periods and reduced mortality rates. Neonate T. leucotreta were also attracted to YPD broth cultures inoculated with yeast for feeding. Oviposition preference assays were conducted with adult T. leucotreta females. Navel oranges inoculated with yeast were shown to influence the oviposition preference of adult females. Yeasts harbour the potential for use in biocontrol, especially when combined with other well-established control methods. This study provides a platform for future research into incorporating yeast with current biological control agents as a novel option for controlling T. leucotreta in the field.
桃蛀果蛾原产于南部非洲，由于其被列为植物检疫性害虫，对包括南非柑橘产业在内的各种水果产业具有重大影响。与桃蛀果蛾密切相关的苹果蠹蛾与酵母之间的互利共生关系此前已有描述，并据报道可降低幼虫死亡率并促进幼虫发育。在此，我们确定了桃蛀果蛾幼虫肠道中天然存在哪些酵母物种，并研究了任何分离出的酵母物种是否会影响它们的行为和发育。从南非地理上不同的省份收集了感染桃蛀果蛾幼虫的脐橙，对幼虫进行处理以分析天然存在的相关酵母。通过对rDNA的ITS区域和大核糖体亚基的D1/D2结构域进行PCR扩增和测序，从这些桃蛀果蛾幼虫的肠道中分离并鉴定出六种酵母物种。进行了幼虫发育和引诱试验，以接种酵母的脐橙为食的桃蛀果蛾幼虫发育周期加快，死亡率降低。初孵桃蛀果蛾也被接种酵母的YPD肉汤培养物吸引去取食。对成年桃蛀果蛾雌性进行了产卵偏好试验。结果表明，接种酵母的脐橙会影响成年雌性的产卵偏好。酵母具有用于生物防治的潜力，特别是与其他成熟的防治方法结合使用时。本研究为未来将酵母与当前生物防治剂结合作为田间防治桃蛀果蛾的新选择的研究提供了一个平台。
