CIMAINA, Physics Department, Università degli Studi di Milano, Via Celoria 16, 20133, Milano, Italy.
Department of Biosciences and Pediatric CRC "Romeo ed Enrica Invernizzi", University of Milan, Milan, ItalyVia Celoria 26, 20133, Milan, Italy.
Soft Matter. 2022 Aug 31;18(34):6443-6452. doi: 10.1039/d2sm00889k.
Biological methods for mosquito larvae control are completely biodegradable and have null or limited effects on nontarget organisms. However, commercially available products have a low residual activity, with the consequent need for multiple applications that inevitably increase costs and the risk of resistance phenomena insurgence. Smart delivery systems made of hydrogels proved their efficacy in increasing the action duration of biolarvicides up to several months, but the lack of an efficient baiting mechanism to strongly attract the target pest remains a problem in practical applications. In this work, we investigated two novel hydrogel-based formulations of completely natural composition for baiting and killing larvae of mosquitos. The proposed materials consist of charged crosslinked polysaccharides (chitosan and cellulose) and are specifically manufactured to float in water, simulating organic matter usually present at breeding sites. Within the hydrogels' matrix, yeast colonies of were embedded as phagostimulants alongside a biolarvicide ( var. ()). Despite the similar chemical nature and structure, chitosan-based hydrogels exhibited a markedly superior baiting potential compared to those made of cellulose and also succeeded in efficiently killing mosquito larvae just after a few hours from administration. We are confident that the proposed smart delivery hydrogel made of chitosan can be an enabling tool to attract mosquito larvae towards biopesticides of different nature without delocalizing active ingredients away from the breeding site and to simultaneously increase their residual activity, thus holding the potential of minimizing environmental pollution related to pest control and vector-borne disease prevention.
生物方法控制蚊子幼虫是完全可生物降解的，对非目标生物几乎没有影响或影响有限。然而，商业上可用的产品的残留活性较低，因此需要多次应用，这不可避免地增加了成本和产生抗药性的风险。水凝胶制成的智能输送系统已被证明可以有效延长生物杀幼虫剂的作用时间，长达数月，但缺乏有效的诱捕机制来强烈吸引目标害虫，这在实际应用中仍然是一个问题。在这项工作中，我们研究了两种新型基于水凝胶的完全天然配方，用于诱捕和杀死蚊子幼虫。所提出的材料由带电荷的交联多糖（壳聚糖和纤维素）组成，专门用于在水中漂浮，模拟通常存在于繁殖地的有机物。在水凝胶的基质中，酵母的菌落被嵌入作为诱食剂，同时还有一种生物杀幼虫剂（var. ()）。尽管化学性质和结构相似，但基于壳聚糖的水凝胶的诱捕潜力明显优于基于纤维素的水凝胶，并且在给药后仅几个小时就能有效地杀死蚊子幼虫。我们相信，所提出的基于壳聚糖的智能输送水凝胶可以成为一种有效的工具，将蚊子幼虫吸引到不同性质的生物农药中，而不会将活性成分从繁殖地转移开，并同时提高其残留活性，从而有可能最大限度地减少与害虫控制和媒介传播疾病预防相关的环境污染。
