Application of Black Soldier Fly Frass, Hermetia illucens (Diptera: Stratiomyidae) as Sustainable Organic Fertilizer for Lettuce, Lactuca sativa Production

In recent years, black soldier fly (BSF) has been shown to efficiently convert organic waste into nutrient-rich larval biomass while generating frass as the main by-product. This work aims to investigate the potential of BSF frass (BSFF) as an organic fertilizer for agricultural production. BSFF was produced by recycling household waste using BSF larvae, and a portion was taken to the lab for physicochemical and microbial analyses before the field trial on lettuce growth and health. The field trial consisted of two doses of BSFF (15 t·ha-1 and 30 t·ha-1) and one dose of urea (0.214 t·ha-1). An unfertilized plot was prepared and used as a control, and the effects on lettuce growth were assessed using agronomic parameters while the health effects were assessed using parameters such as: the number of leaves affected per plant, the incidence of affection, the severity of the affection and the microbial analysis. BSFF exhibited acceptable physicochemical properties as an organic fertilizer. Its application improved the growth parameters of lettuce plants compared to urea and control. The application rates of 15 t·ha-1 and 30 t·ha-1 did not reveal any significant difference (p > 0.05). Further studies are therefore needed to determine the minimum applicable dose. The health parameters of the lettuce plants were slightly altered regardless of the treatment and the microbial analysis of the affected leaves revealed pathogenic microorganisms. We therefore recommend that decontamination methods be considered when producing BSFF as an organic fertilizer.

虫粪在森林昆虫识别中的应用初探

在较高大树木上危害的森林昆虫,当其种群的密度不是很高,或种群未处于大量取食的虫态(一般为末龄幼虫)时,往往不易被发现。大量取食后不久,种群突然消失,只留下一些危害过的痕迹。危害痕迹中寄主林木被害状能提供的信息极有限,害虫的头壳也很难找到,而虫粪却易于发现且能提供较多的信息,成为确定害虫种类的线索。国外已有不少文献肯定了虫粪对于识别虫种的辅助作用,还编制了若干种森林害虫的虫粪检索表。国内仅对马尾松毛虫虫粪在监测其幼虫种群数量方面作过较详细的研究,尚未见到用虫粪识别虫种方面的研究。

松毛虫虫食叶和排泄物对土壤激发效应的影响

昆虫冠层取食导致大量的虫食叶和排泄物输入到地表,对森林土壤碳循环产生重要影响。然而,目前关于虫食叶和排泄物影响土壤激发效应的研究仍十分匮乏。本研究以马尾松为对象,应用13C同位素自然丰度法研究马尾松凋落叶、松毛虫虫食叶和排泄物添加对土壤激发效应强度和方向的影响。结果表明:马尾松凋落叶、虫食叶和排泄物添加均促进土壤有机碳的分解,即产生正激发效应,且各处理之间差异显著。松毛虫排泄物诱导的累积激发效应最大,虫食叶次之,马尾松凋落叶诱导的累积激发效应最小。线性回归分析表明,在培养前期,激发强度与添加物全磷、缩合单宁、缩合单宁/P以及总酚含量呈显著正相关,与C/N、木质素/N、C/P、木质素/P呈显著负相关;在培养后期,激发强度与木质素含量呈显著负相关。综上,松毛虫虫害产生的虫食叶和排泄物提高了土壤激发效应强度,且在不同培养阶段控制激发强度的主导因子不同,这有助于加深对虫害影响森林土壤碳循环的认知,并提高对虫害影响森林生态系统碳汇的估算精度。

虫粪中信息化学物质的研究进展

排便是昆虫的一个重要生理过程,排便行为不仅可以清除食物残渣,而且可以释放某些化学信息,进而影响昆虫同种或异种之间的相互作用。昆虫粪便中的信息化学物质不仅影响同种昆虫的聚集、求偶行为,而且可以影响同种和异种昆虫的产卵行为。此外,虫粪还能为其天敌昆虫的寄主定位和识别提供信息,并能通过诱导植物的防御反应抑制植食性昆虫的取食行为。本文根据国内外的相关研究,对虫粪中存在的信息化学物质进行了分类总结,并介绍了虫粪信息化合物在害虫防治中的应用,还讨论了目前存在的问题和研究前景。