Azadirachtin exhibits excellent bioactivities against several hundred arthropods. However, current knowlege of its biochemical effect on B. dorsalis larvae is not deep enough. In this study, integrated LC-MS and GC-MS-based untargeted metabolomics were used to analyze the changes of endogenous metabolites and the biochemical effects of azadirachtin on B. dorsalis larvae. Azadirachtin has excellent bioactivities against B. dorsalis larvae in this study, leading to a longer developmental duration, lower survival rate, and low pupa weight. The effect of azadirachtin was investigated on a total of 22 and 13 differentially abundant metabolites in the LC-MS and GC-MS-based metabolomics results, are selected respectively. Pathway analysis indicated that 14 differentially enriched metabolic pathways, including seven influential pathways, are worthy of attention. Further integrated key metabolic pathway analysis showed that histidine metabolism, d-glutamine and d-glutamate metabolism, biotin metabolism, ascorbate and aldarate metabolism, pentose and glucuronate interconversions, and alanine, aspartate and glutamate metabolism in B. dorsalis larvae are significantly relevant pathways affected by azadirachtin. Although extrapolating the bioactivity results in this study to the practical project of B. dorsalis pest management in the field has limitations, it was found that azadirachtin has a significant effect on the primary metabolism of B. dorsalis larvae.Bactrocera dorsalis is a destructive polyphagous and invasive insect pest of tropical and subtropical fruits and vegetables; this oriental fruit fly has been found to attack many types of commercial fruits and a wide variety of agricultural products 1 . Azadirachtin exhibits excellent bioactivities against agricultural, forestry, medical, and veterinary arthropods 2-4 . However, studies on the effects of azadirachtin on B. dorsalis are scarce. Azadirachtin is the main active ingredient in neem. It was reported that neem derivatives are ineffective when used as toxic bait for tephritid fruit flies 5 . Several studies reported that neem seed kernel extracts and azadirachtin deters oviposition of B. dorsalis adults 6,7 . Neem leaf dust significantly reduced the longevity and fertility of B. dorsalis adults by blocking ovarian development 8 . Neem extract could effectively reduce the fecundity, fertility, and post-embryonic development of freshly emerged B. dorsalis flies 9 . However, we found no previous studies in the literature on the activity of azadirachtin against the larvae of B. dorsalis.The biological effects of azadirachtin include impacts on egg-laying behavior, feeding behavior, growth and metamorphosis, reproduction, activity, and histopathology 10 . The mode of action of azadirachtin against lepidopteran insects can be explained, in part, by effects on digestive enzymes, NADPH cytochrome reductase, and cholinesterase 11 . The physiological effects of azadirachtin include direct inhibition of cell division and protein synthesis 12 . The indirect effects of blocki...
Drosophila is a common strawberry pest. In this work, toxicities of the 77.5% EC dichlorvos to 3rd instar larvae and adults of drosophila were evaluated through indoor bioassays and field bioassays, respectively. To insure the safety, dichlorvos dissipation and terminal residue in strawberry by different application methods under field conditions were determined by high-performance liquid chromatography. The decline curves of dichlorvos residues in strawberry corresponded with first-order kinetics, and dichlorvos dissipated rapidly in strawberry with half-life (t) of 7.58-13.17 h. Terminal residues below the maximum residue limit of strawberry and soil in different distance were achieved after 24 h under different application methods. This article provides guidance to the proper and safe use of dichlorvos in agriculture; it is more reasonable that dichlorvos is applied by embedding on the ground near the strawberry plants covered plastic film with holes.
An integration algorithm for clustering is presented, in which a maximization & minimum algorithm to determine the initial centers and BWP (Between-Within Proportion) index for input of optimal k. In theory, the bigger the BWP index, the better the clustering effectiveness. Then a numerical example of air transport market segment is presented to show the effectiveness and efficiency of the method presented in the document.
Finite element analysis is carried out on the dynamic splitting tensile mechanical properties of reinforced concrete with LS-DYNA. The impact of strain rate and reinforcement ratio on the dynamic tensile strength and failure mode of reinforced concrete is considered in the calculation. The result shows that the form of reinforcement and reinforcement ratio has a greater impact on the failure mode and tensile strength of concrete. The dynamic splitting tensile strength of reinforced concrete has a certain strain rate effect and its splitting tensile strength increases with the strain rate; the splitting tensile strength of reinforced concrete also increases with its reinforcement ratio.
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