Effectiveness of cyfluthrin dust treatment for control and protection of shelled maize against infestation by the larger grain borer,Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) in Tanzania

Abstract

Knockdown, mortality and residual activity of pyrethrins and cyfluthrin were studied on the larger grain borer (LGB), Prostephanus truncatus (Horn). Pyrethrum marc with 0.4% pyrethrins and cyfluthrin dust (0.1% a.i.) when applied on filter paper at 0.72 mg/cm² gave 98.6% and 100% knockdown (KD) respectively after 6 h. Cyfluthrin dust had a faster KD effect with 100% KD compared to 93.1% for pyrethrum marc, ½1/2>h after treatment. After 24 h there was no recovery from KD in both treatments. After 72 h, 23.2% of the LGB had recovered from KD while mortality was 76.8% in the pyrethrum marc treatment. After the same period, cyfluthrin resulted in 100% mortality. Mortality of P. truncatus exposed to different dosages of cyfluthrin dust in shelled maize was less than 100% at dosages lower than 1 part per million (ppm) but was 100% at 1 ppm and higher dosages 3 days after treatment. Progeny emergence was suppressed at all dosage levels above 0.25 ppm compared to a mean progeny of 68.8 in the check after 45 days. Cyfluthrin dust was more residually toxic at 0.5 ppm and higher dosages, with mortality of >90% at 5 months after treatment. This suggests that cyfluthrin dust at 0.1% a.i. mixed with shelled maize at 1 ppm will give protection and control of LGB infestation.     

The pyrethrins and related compounds. Part XXXVIII—optimisation of insecticidal activity in 3-[(alkoxyimino)methyl]-4-fluorobenzyl esters

Optimisation of activity in 3-[(alkoxyimino)methylbenzyl] esters has been investigated by introducing an α-cyano group and a fluorine atom in position 4 of the benzylic moiety in conjunction with varying the length and nature of the side chain. Of the five side-chain variations investigated, the 3-methoxyiminomethyl was more effective than others. Introduction of fluorine in position 4 of the benzylic moiety generally increased activity, particularly against mustard beetles, as in previous instances. Surprisingly, the effect on insecticidal activity of introducing an α-CN group ranged from positive to negative depending upon the nature of the alkoxyimino substituent, an effect not observed previously. The most effective esters were derived from α-cyano-4-fluoro-3-[(methoxyimino)methyl]benzyl alcohol, which was synthesised from 2-{4-fluoro-3-[(hydroxyimino)methyl]phenyl}-1,3-dioxolane.     

拟除虫菊酯类农药对哺乳动物神经毒理的研究进展

对拟除虫菊酯类(SPs)农药对哺乳动物的神经毒理学研究过程及其最新进展进行了综述。拟除虫菊酯类农药是目前使用广泛的一类神经毒性杀虫剂,主要用于农业和卫生害虫的防治。已有研究结果显示拟除虫菊酯类农药对非靶标野生动物和人类的神经系统有一定的毒性作用,其对哺乳动物的神经毒性主要表现为急性和慢性神经毒性,而且其毒性作用与拟除虫菊酯类农药的立体结构相关,有一定的对映体选择性差异。     

The pyrethrins and related compounds part XXXIX— structure-activity relationships of pyrethroidal esters with cyclic side chains in the alcohol component against resistant strains of housefly (Musca domestica)

Activities of a range of pyrethroidal esters, incorporating structural variations in all regions of the acid and alcohol components, have been measured against two fully characterised and homozygous resistant strains of Musca domestica L. (kdr and super-kdr). The results, limited in this paper to esters of alcohols with cyclic side chains, indicate uniform resistance to the kdr strain across the whole range of structural variations. Against the super-kdr strain, while variation in the acid component has little effect, the resistance factor is sensitive to the nature of the alcohol component, in particular on whether it contains an α-cyano substituent.     

The pyrethrins and related compounds part XL— structure-activity relationships of pyrethroidal esters with acyclic side chains in the alcohol component against resistant strains of housefly (Musca domestica)

Activities of a range of pyrethroidal esters, incorporating structural variations in all regions of the acid and alcohol components, have been measured against two fully characterised and homozygous resistant strains of Musca domestica (kdr and super-kdr). The results, limited in this paper to esters of alcohols with acyclic side chains, show the same level of uniform resistance as the kdr strain observed previously, across a range of acid and alcohol variations. Against the super-kdr strain, in contrast to the cyclic side chain set, resistance factors are barely higher than for the kdr strain. Against super-kdr flies, some dependence of resistance factor on the position of the side chain substituent was detected. Polyfluorobenzyl esters confer particularly low resistance factors.     

Trends in the formulation of pesticides—an overview

The customer increasingly requires safer and more convenient pesticide formulations. Emulsifiable concentrates and wettable powders are nowadays viewed less favourably by farmers and registration authorities. Suspension concentrates are now common and water-dispersible granules and emulsions in water are receiving increasing attention. Capsule suspensions offer both safer and more effective performance in favourable cases. For convenience the farmer requires multi-component products, either as mixtures of active ingredients, which might be as suspoemulsions, or with built-in enhancing surfactants and oils. Seed treatments are now required as aqueous suspensions and the seed is increasingly of interest as an eficient carrier for pesticides. Research into biological control agents sets the difficult challenge of formulating these products as viable organisms. Three examples of developments are described. These are the applications of polymeric surfactants for suspension concentrates and suspoemulsions, studies of enhancement of pesticide uptake with surfactants and developments in microencapsulation.     

不同壁材高效氯氰菊酯微囊悬浮剂在土壤中迁移与光解的差异性

分别制备了以脲醛树脂、密胺树脂、聚氨酯和聚脲为壁材的10%高效氯氰菊酯微囊悬浮剂,采用土壤薄层层析法、紫外光解法和室内自然光照对比法,通过高效液相色谱测定了各微囊悬浮剂在土壤中的迁移以及在紫外光和自然光照下的光解作用。结果表明:在粒径相近的情况下,以水为展开剂时,分别以聚脲、聚氨酯、密胺树脂和脲醛树脂为壁材的微囊悬浮剂的迁移性依次减小;同一壁材的微囊悬浮剂,迁移性随粒径增加而增大;在紫外光照射下,光解速率由大到小依次为高效氯氰菊酯原药,10%高效氯氰菊酯乳油,以及以聚脲、聚氨酯、密胺树脂和脲醛树脂为壁材的微囊悬浮剂,其半衰期分别是2.3、9.4、20.7、39.0、45.8 和51.9 h;在自然光照条件下,上述各药剂的半衰期分别是5.8、5.9、6.9、6.7、12.9和17.3 d。将高效氯氰菊酯制备成微囊悬浮剂后其在自然条件下的光解明显低于原药和乳油,可延长其持效期。     

异硫氰酸烯丙酯的农用活性与应用研究进展

异硫氰酸烯丙酯(allyl isothiocyanate,AITC)是十字花科植物的组成型代谢产物之一,关于其天然抗菌杀虫活性,以及在人类医学、农业、食品等领域的应用已有大量研究。本文重点对AITC的制备、农用活性及残留、安全性及作用机制研究等方面进行综述,以期为AITC在农业中的开发应用提供理论参考和技术支撑。