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Turfgrass Insects
Published in L.B. (Bert) McCarty, Golf Turf Management, 2018
Insect growth regulators (IGRs). Insect growth regulators are a class of artificial compounds currently being developed that mimic the action of the natural hormone, ecdysone. IGRs interfere with the normal insect molting process, causing insect mortality, or they alter juvenile hormones, preventing insects from maturing. These also can inhibit the production of chitin, a polymer composite of the insect’s exterior. The process is rate dependent and insect specific. Suboptimal application rates cause sublethal effects such as rapid maturation of insects to adult stages and deformities of larvae. As mentioned, certain IGRs are more effective on specific insects; therefore, the turf manager must identify the insect present for maximum effectiveness.
Biological Responses in Context
Published in Arthur T. Johnson, Biology for Engineers, 2019
Antagonistic hormone control pervades living systems. Blood calcium level in mammals is regulated by the action of two hormones with opposing effects: calcitonin produced in the thyroid gland that reduces calcium and parathyroid hormone (PTH) that raises its level (Figure 6.20.9). Insect development is controlled by the hormones ecdysone and juvenile hormone (JH); ecdysone stimulates molting of the exoskeleton and growth, but the presence of JH hinders development of pupa and adult stages; only when JH levels wane does the insect progress to the next life-form stage.
A comparative study on aquatic toxicity of chemically-synthesized and green synthesis silver nanoparticles on daphnia magna
Published in International Journal of Environmental Health Research, 2022
Feyza Içoglu Aksakal, Asli Yilmaz, Kubra Koc, Selçuk Özdemir
Although there have been many reports on the aquatic toxicity of AgNPs in aquatic organisms, further studies are still required to determine their toxicity levels, mechanism, and comparison between nanoparticles prepared through different approaches. Herein, we evaluated the toxicity of Gr-AgNPs and Che-AgNPs in D. magna. We employed the extract of Salvia aethiopis L. plant leaves in the synthesis of Gr-AgNPs. In addition to toxicity tests, the expression of some genes related to detoxification (cyp360a8, gst, and hr96) and reproductive system (cyp314, and vtg) was performed to find out probable mechanism behind the toxicity, as many environmental pollutants can change the expression of the detoxification and antioxidant-related genes such as cyp’s and gst. In this study, hr96, cyp314, gst, and vtg have been selected as target genes since hr96 can regulate the expression of phase I, II, and III detoxification genes, cyp314 plays a role in the biosynthesis of ecdysone hormone, gst protects cells against reactive oxygen species, and vitellogenin, the precursor of the egg yolk protein, is a biomarker frequently used for exposure to estrogenic compounds. To the best of our knowledge, this is the first comparative report showing the differences in toxicity of Che-AgNPs and Gr-AgNPs in D. magna in terms of survival rate and gene expression level.