Neonicotinoid Insecticides Nitenpyram Research Articles

Photodegradation of Neonicotinoid Insecticides Nitenpyram, Thiacloprid, and Acetamiprid in Water and Soil Environments.

The photodegradations of three selected neonicotinoid insecticides nitenpyram, thiacloprid, and acetamiprid were investigated in both water and soil samples under natural sunlight, UVA light, and UVB light. The results indicate that these insecticides undergo significant degradations when subjected to sunlight, whether they are in deionized (DI) water, tap water, and DI water containing 100mg/L humic acids or in soil. The degradation half-lives of nitenpyram, thiacloprid, and acetamiprid in tap water under sunlight were found to be 3.7, 4.7, and 8.9h, respectively, in DI water 5.4, 6.3, 9.1h, respectively, in DI water containing 100mg/L humic acids 3.6, 3.3, 6.5h, respectively, and in soil 7.5, 7.9, and 15.9h, respectively. The degradation due to hydrolysis was found insignificant as compared to photodegradation. The examination of the effects of light source revealed that the UVB in the sunlight plays a major role in the photodegradation of these three neonicotinoids, and the effects of UVA and visible light are negligible. The analysis on the degradation products indicated that the nitroguanidine group in these insecticides is unstable and prone to break up under sunlight. A total of nine degradation products were detected, of which the health effects and the fate and transport in the environment need to be further studied.

Monitoring of insecticide resistance for Apolygus lucorum populations in the apple orchard in China

Apolygus lucorum (Meyer-Dur) (Hemiptera: Miridae) is an important piercing-sucking pest that has been recorded on more than 200 host plants in China. In recent years, its damage to apple trees has become more and more serious, resulting in malformed fruit and even fruit shedding. It is primarily controlled with insecticides. However, the current status of insecticide resistance of A. lucorum in the apple orchard is rarely reported. In this study, we determined the susceptibility of one laboratory population and six geographic field populations of A. lucorum to ten chemical and six botanical insecticides by glass-vial and artificial diet bioassays. The results showed that among the ten chemical insecticides, bifenthrin exhibited the highest toxicity to this pest by glass-vial bioassays than other insecticides, followed by chlorpyrifos, and then one of the neonicotinoid insecticides nitenpyram. In the artificial diet bioassays, the LC50 values of the avermectin insecticides to A. lucorum populations were significantly lower than those of other classes of insecticides, followed by neonicotinoid insecticides. Among six botanical pesticides, veratramine and pyrethrins showed higher toxicity to A. lucorum populations, while rotenone and cnidiadin exhibited poor effects. The results indicated that chlorpyrifos, bifenthrin, avermectin, and emamectin benzoate could be recommended to mix or rotate with botanical pesticides veratramine and pyrethrins in controlling A. lucorum in the apple orchard. Our study would provide valuable information for choosing alternative insecticides and for insecticide resistance management of A. lucorum.

Biotransformation and detoxification of the neonicotinoid insecticides nitenpyram and dinotefuran by Phanerochaete sordida YK-624

Neonicotinoid insecticides have been widely used throughout the world over the last two decades. In the present study, we investigated the degradation of neonicotinoid insecticides nitenpyram (NIT) and dinotefuran (DIN) by the white-rot fungus Phanerochaete sordida YK-624. While NIT was completely degraded by P. sordida YK-624 under ligninolytic conditions, only a 20% decrease was observed under nonligninolytic conditions. On the other hand, P. sordida YK-624 degraded 31% of DIN under ligninolytic conditions after a 20-day incubation, while it did not degrade DIN under nonligninolytic conditions. We found that cytochromes P450 played a key role in the biotransformation of NIT and DIN by P. sordida YK-624. A novel NIT metabolite (E)-N-((6-chloropyridin-3-yl)methyl)-N-ethyl-N′-hydroxy acetimidamide (CPMHA) and a novel DIN metabolite N-((4aS,7aS,E)-1-methylhexahydrofuro[2,3-d]pyrimidin-2(1H)-ylidene)nitramide (PHPF) were identified in this study. In addition, to evaluate neurotoxicity, the effects of NIT, DIN and their metabolites on the viability of human neuroblastoma cells SH-SY5Y were determined. PHPF showed higher neurological toxicity than DIN, whereas the metabolite of NIT, CPMHA, showed no toxic effect. Our results indicated that the neurological toxicity of NIT could be effectively removed by P. sordida YK-624.

LIMITS OF QUANTIFICATION OF SOME NEONICOTINOID INSECTICIDES MEASURED BY THIN-LAYER CHROMATOGRAPHY

A simple method to quantify the neonicotinoid insecticides nitenpyram, thiamethoxam, acetamiprid, imidacloprid, thiacloprid, and clothianidin directly on an HPTLC-plate is presented. As stationary phase silica gel 60 RP-18WF254 s plates were used and a mixture of methyl-t-butyl ether, 2-butanone, NH3 (25%) (5 + 2+0.1, v/v) was used as solvent. All neonicotinoid insecticides show light absorptions below 300 nm. The calculated limits of quantification (LOQ) by UV-detection were in the range from 12 ng to 26 ng on plate depending on the different insecticides. Nitenpyram can be stained using fast blue salt B, forming red zones. The observed LOQ is 25 ng on plate. Acetamiprid can be specifically stained using phenylglyoxylic acid forming a yellow/green fluorescent compound. The LOQ is 52 ng per spot. The compounds thiamethoxam, acetamiprid, thiacloprid, and clothianidin can be transformed into blue fluorescing zones, using a relatively new staining solution. This consists of tetraphenylborate and HCl. This is the first publication mentioning that neonicotinoids undergo this reaction. The calculated limits of quantification are in the range from 10 ng to 27 ng on plate. A simple pre-treatment procedure using an acetonitrile extraction and a Chromabond SiOH clean up procedure leads to overall LOQs for bee samples of 48–108 µg/Kg. The method can be used to measure neonicotinoid contaminations of bees.