Sublethal effects of nine insecticides on Drosophila suzukii and its major pupal parasitoid Trichopria drosophilae

Background

Although the pupal parasitoid Trichopria drosophilae is used in conservative and augmentative biocontrol of Drosophila suzukii infestations, current pest management strategies mostly rely on multiple insecticide applications. In this context, the aim of the study was to investigate the baseline toxicity of nine insecticides on D. suzukii larvae and their multiple sublethal effects (LC₁₀) on immature stages of the pest feeding on contaminated diet and T. drosophilae developing within the intoxicated host.

Results

Chlorpyriphos and azadirachtin showed the lowest and the highest LC₁₀, the values of which were 9.78 × 10¹³ and 1.46 × 10³ times lower than their recommended label field rate, respectively. Among tested insecticides, imidacloprid, malathion and dimethoate were the only treatments that did not affect the juvenile development time of D. suzukii, while spinosad and the organophosphates chlorpyriphos and dimethoate did not influence fly pupal size. No sublethal effects were recorded on T. drosophilae degree of infestation (DI) and juvenile development time. On the contrary, cyazypyr and dimethoate negatively affected the success of parasitism (SP) and the number of progeny of the pupal parasitoid, in association with malathion for the first parameter and spinosad for the fertility. Compared to the untreated control, more female progeny emerged following azadirachtin exposure, while dimethoate caused the opposite effect. Imidacloprid, lambda-cyhalothrin and spinetoram decreased hind tibia length of emerged parasitoids.

Conclusion

This study provides new insights on the (eco)toxicological profile of nine insecticides and new information needed to support the deployment of T. drosophilae in the field within the sustainable management techniques against D. suzukii. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Bacterial community structure in lake sediments of microcosms contaminated with nonylphenol

The impact of nonylphenol, an estrogenic degradation product of alkylphenol polyethoxylates, on the bacterial community structure in contaminated sediments of aquatic microcosms was investigated over a period of 20 weeks using a 16S rDNA-based molecular phylogenetic approach. All microcosms showeda strong seasonal fluctuation of the dominant as well as the active bacterial microflora independent of their degree of contamination with nonylphenol. These changes were correlated with the dynamic of the total organic carbon content (TOC), ranging from 4–39 g/kg sediment dry weight and the redox potential in the sediment. Even at the highest observed nonylphenol concentration (3.4 mg/kg sediment dry weight) the bacterial community structure was mostly unchanged.     

Effects of antibiotics on soil microorganisms: time and nutrients influence pollution-induced community tolerance

A method for the detection of the effects of antibiotics on soil microbial communities was optimised in the present study. We investigated the influence of measurement time and nutrient status on the pollution-induced community tolerance (PICT), using the sulfonamide sulfachloropyridazine (SCP) as model compound. The tolerance development in soil microcosms that were exposed to SCP under different conditions was compared with the background tolerance in SCP-unexposed microcosms. The tolerance of bacterial extracts from the soil microcosms was determined in Biolog^® multiwell plates as the SCP sensitivity of a range of physiological processes. The background tolerance was not affected by soil nutrient amendments, but an influence of the inoculum density in the microtiter plates was observed. Still, the variance of the background tolerance was low, which is in favour of the usage of community tolerance measurements for a selective detection of a toxicant impact. In line with the assumptions of the PICT concept, soil amendment with SCP led to an increase in community tolerance. This tolerance development was enhanced upon additional soil amendment with fresh pig slurry, and less by alfalfa meal addition. Tolerance increases were observed after a soil exposure to SCP of only 7 days, possibly because nutrient input facilitates the fast adaptation of the soil microbial community. However, a further increase in exposure time led to variable changes in the observed tolerance. Prolonged tolerance detection in the microtiter plates (11 days) enabled a clearer differentiation between different soil treatments, as it better resolved the EC₅₀ values of processes with a high tolerance to bacteriostatic antimicrobial compounds. For the detection of antibiotic effects on soil microbial communities, it is therefore recommended to use nutrient amendments (possibly fresh pig slurry), to standardize the soil exposure time, and to extend the period of Biolog plate measurement beyond 7 days.     

农药生态毒理学概念及方法学探讨

农药生态毒理学是横跨毒理学、农药学和生态学的一门交叉学科。文章从"关注对象"、"关注层面"、"学科归属"和"成果应用"4个方面归纳了"农药生态毒理学"与"农药环境毒理学"的区别,并从"试验历期"、"剂量设置"、"可控性"、"暴露评估"以及"研究的阶段性"等不同侧面阐述了农药生态毒理学研究的方法学要素。对于除人类以外的非靶标生物的关注以及提倡用生态学方法进行研究,是农药生态毒理学区别于农药环境毒理学的明显特征。按照试验历期的长短,农药生态效应评估试验可分为"急性"、"亚急性"和"慢性"3类;按照试验条件的可控性,则可分为"室内"、"半田间"和"田间"3个层次。从经济和时效性角度考虑,农药生态效应评估试验应遵从先急性、后慢性,先室内、后田间的顺序;为避免出现"假阴性"结果,试验设计时应确保受试生物在室内试验中所受的胁迫强度高于半田间或田间试验。鉴于农业生态系统的多样性和复杂性,农药生态毒理学家应该有意识地使其研究内容和研究方法与现有的农药生态风险评估体系相衔接,惟其如此,相关研究成果的生态学意义才能够得到充分体现。随着人们对农药与农业生态系统相互关系认识水平的提高,农药生态毒理学在理论及实践方面将会得到进一步发展,并将反过来促进农药生态风险评估体系的发展和完善。     

Biological tools for the assessment of contaminated land: applied soil ecotoxicology

Abstract. Chemical analysis alone is inadequate for comprehensively assessing the impact of soil pollution on biota. The term bioavailability can only be applied in a context specific to a target biological receptor or a proven chemical surrogate. Integration of biological and chemical data can often yield significant advances in hazard assessment and act as a suitable baseline for making site-specific risk assessments. Here, the value of biological techniques is discussed and their application described. The relative merit of test selection is considered and the new direction being developed in sublethal assessments. Currently, however, one of the major limitations is the seeming lack of flexibility of many assays in that they are either applicable to agricultural systems or industrial scenarios, but rarely to both. As a consequence, few assays have internationally adopted protocols. The introduction of new methods and the continued improvement and refinement of assays make this area of soil science dynamic and responsive.     

An ecological risk assessment for spinosad use on cotton

Spinosad is a reduced-risk insecticide with a novel mode of action that provides an alternative to older classes of insecticides such as organophosphates, carbamates and pyrethroids. A comprehensive ecological risk assessment for spinosad use in US cotton crops is presented within a framework of tiered levels of refinement following the guidelines of the US EPA for ecological risk assessments. Toxicity information for a variety of species is documented and utilized, environmental concentrations estimated, and risk characterizations in the form of risk quotients are quantified. Results indicate that spinosad use in cotton does not exceed the most conservative Tier I levels of concern (LOC) values for groundwater, mammals and birds or acute risk to aquatic organisms. Use of very conservative Tier I screening methods resulted in exceeding LOC values for chronic exposure for some aquatic organisms, thus prompting further refinement. When the exposure prediction was refined using less conservative, Tier II mechanistic environmental fate transport models to predict offsite transport and environmental concentrations, chronic risk was not predicted for these species. Spinosad is acutely toxic to bees under laboratory conditions, but toxicity of residue studies and field studies indicate that under actual use conditions the impact on bees is minimal.     

兽药对生态环境影响的研究进展

综述了兽药对陆生和水生生态环境影响方面的研究进展，探讨了兽药对陆生植物、土壤动物、土壤微生物与原生生物等陆生生态环境的影响及对浮游类生物与微生物、鱼虾与水体甲壳动物等水生生态环境的影响及其生态毒理效应。     

线虫 Caenorhabditis elegans在甲基磺酸乙酯(EMS)中的毒性实验

基于C．elegans这种非寄生线虫,在生物遗传变异研究中的重要性与必要性,同时EMS(甲基磺酸乙酯)这种生态毒物,常用来作为生物实验中的诱变试剂,二者常常被同时选择作为生物基因遗传领域研究的对象。为定量了解EMS对线虫C．elegans的毒性作用,设计本实验,通过线虫的培养、线虫在EMS溶液中24h暴露、实验结果观察和分析这三个步骤,经过反复实验,摸索实验条件,进行浓度优化,从大量的数据汇总得到了其LC50的数值。为进一步对C．elegans的生物、生态、基因、遗传研究提供了良好的基础。也为通过线虫的生物理解来破解我们人类对自己物种的生物理解做前期的工作。