大链壶菌感染对致倦库蚊幼虫体内蛋白质及游离氨基酸的影响

目的 从生物有机化学的角度探讨大链壶菌的灭蚊机制。方法 采用生物分析化学技术测定正常蚊幼虫（蚊幼）与感染大链壶菌后不同时期蚊幼组织中蛋白质含量和26种游离氨基酸的变化。结果 正常蚊幼体内蛋白质随时间延长明显增加，而实验组蚊幼在被感染后24h和48h其体内蛋白质增加的幅度明显低于对照组，游离氨基酸测定结果显示，感染开始时，感染组蚊幼体内丝氨酸（Ser)含量明显低于对照组，组氨酸（His)含量明显高于对照组；感染24h,Ser,牛磺酸（Tau)，苏氨酸（Thr)，谷氨酸（Glu)，谷氨酰胺（Gln)，丙氨酸（Ala)，甲硫氨酸（Met)。酷氨酸（Tyr)，γ-氨基丁酸（Gaba)含量明显低于对照组，半胱氨酸（Cys)。瓜氨酸（Cit),His含量明显高于对照组；感染48h，羟脯氨酸（HyP)，胱硫醚（Hcy)，异亮氨酸（Ile)。亮氨酸（Leu)。苯丙氨酸（Phe),Gaba,His含量与对照组差异不明显，Cys,γ-氨正己酸（Aad),Cit明显高于对照组，其余氨基酸含量明显低于对照组，结论 大链壶菌感染引起蚊幼体内蛋白质及多种游离氨基酸含量的变化，导致体内营养代谢与生理功能紊乱，阻碍了蚊幼的正常发育和生命活动，是造成蚊幼死亡的重要原因。     

大链壶菌对致倦库蚊幼虫三种酶活性的影响

[目的 ]从生化代谢角度探讨大链壶菌灭蚊机制。 [方法 ]采用酶组织化学方法测定正常蚊幼与不同程度感染大链壶菌的蚊幼体内碱性磷酸酶 (AKP)、酸性磷酸酶 (ACP)及酯酶 (EST)活性 ,用显微摄影及定量图像法进行观察。其中 ,用钙 钴法检测AKP ,硝酸铅法检测ACP ,α 醋酸萘酚法检测EST活性。 [结果 ]用计算机图像分析仪检测 10～ 15个标本的单位面积平均黑度值 ,发现大链壶菌潜在感染蚊幼AKP和ACP活性降低 ,轻度感染和重度感染蚊幼酶活性降低明显 ;而EST活性在不同感染程度蚊幼的各种组织中均呈显著升高趋势。 [结论 ]大链壶菌感染引起蚊幼 3种酶活性变化 ,导致体内新陈代谢障碍 ,可能是其致死蚊幼的原因之一。     

大链壶菌感染对致倦库蚊幼虫体内蛋白质及游离氨基酸的影响

目的　从生物有机化学的角度探讨大链壶菌的灭蚊机制。　方法　采用生物分析化学技术测定正常蚊幼虫 (蚊幼 )与感染大链壶菌后不同时期蚊幼组织中蛋白质含量和 2 6种游离氨基酸的变化。　结果　正常蚊幼体内蛋白质随时间延长明显增加 ,而实验组蚊幼在被感染后 2 4 h和 4 8h其体内蛋白质增加的幅度明显低于对照组。游离氨基酸测定结果显示 ,感染开始时 ,感染组蚊幼体内丝氨酸 (Ser)含量明显低于对照组 ,组氨酸 (His)含量明显高于对照组 ;感染 2 4 h,Ser、牛磺酸 (Tau)、苏氨酸 (Thr)、谷氨酸 (Glu)、谷氨酰胺 (Gln)、丙氨酸 (Ala)、甲硫氨酸 (Met)、酪氨酸 (Tyr)、γ-氨基丁酸(Gaba)含量明显低于对照组 ,半胱氨酸 (Cys)、瓜氨酸 (Cit)、His含量明显高于对照组 ;感染 4 8h,羟脯氨酸 (Hyp)、胱硫醚(Hcy)、异亮氨酸 (Ile)、亮氨酸 (L eu)、苯丙氨酸 (Phe)、Gaba、His含量与对照组差异不明显 ,Cys、γ-氨正己酸 (Aad)、Cit明显高于对照组 ,其余氨基酸含量明显低于对照组。　结论　大链壶菌感染引起蚊幼体内蛋白质及多种游离氨基酸含量的变化 ,导致体内营养代谢与生理功能紊乱 ,阻碍了蚊幼的正常发育和生命活动 ,是造成蚊幼死亡的重要原因     

感染大链壶菌后致倦库蚊幼虫血淋巴细胞的观察

目的　探讨致倦库蚊幼虫被大链壶菌感染后可能的免疫防御反应。方法　采用蚊血淋巴涂片 ,姬氏染色光镜检查法结合相差显微镜技术 ,对致倦库蚊幼虫的血淋巴细胞进行观察计数和显微摄影分析。结果　①大链壶菌感染后随感染时间的延长蚊幼单位体积血淋巴细胞数出现“增加、急剧增加、然后逐渐减少”的变化特点。②在感染后 4 8和 72h浆血胞和粒血胞比例明显增加 ,原血胞比例下降 ;在感染后 96及 12 0h ,原血胞比例相对增加 ,珠血胞和类绛血胞所占比例越来越大 ,浆血胞与粒血胞比例相对减少。③感染大链壶菌后 ,浆血胞发生空泡、细胞变形等变化。结论　感染大链壶菌后致倦库蚊幼虫出现血淋巴细胞数量、分类及形态的变化 ,显示大链壶菌在蚊体内诱发了一定程度的免疫防御反应 ,其原因可能是大链壶菌释放某些抗原物质或毒性物质所致     

感染大链壶菌后蚊幼虫脂肪、酯酶和脂肪酶的变化

目的　从蚊虫生理生化代谢角度探讨大链壶菌(Lagenidiumgiganteum)灭蚊机制。　方法　采用组织化学方法检测正常致倦库蚊 (Culexquinquefasciatus)和白纹伊蚊 (Aedesalbopicus)幼虫于感染大链壶菌后不同时间两种蚊幼虫体内的脂肪含量、酯酶和脂肪酶活性,进行显微摄影和定量图像分析。　结果　感染后24h,致倦库蚊幼虫体内的脂肪含量低于对照组,而酯酶和脂肪酶活性高于对照组;感染后48h和72h,两种蚊幼虫体内的脂肪含量均明显低于对照组,酯酶和脂肪酶活性明显高于对照组。　结论　大链壶菌感染引起蚊幼虫体内脂肪含量减少,而与脂肪水解相关的酯酶和脂肪酶活性升高,导致体内脂肪代谢紊乱,是蚊幼虫致死的重要原因     

淡色库蚊和致倦库蚊对广东株班氏丝虫易感性的研究

本文用南京株和合肥株淡色库蚊以及广东株致倦库分别人工感染广东株周期型班氏丝虫，并对其易感性进行比较，用一名微丝蚴密度为２４条／６０μｌ的班氏丝虫微丝蚴血症者血液感染南京株淡色库蚊３３４只，合肥株淡色库蚊１３９只和致倦库蚊２４１只，Ｌ３阳性率分别为１２．５７％、．５．７６％和５．８０％。     

大链壶菌在致倦库蚊幼虫体内温度依赖性发育

大链壶菌(Lagenidium giganteum)是一种很有潜力的生物杀蚊菌,真菌在感染蚊幼虫体内的发育速率对其在宿主种群中的增殖和再循环影响很大。本文观察了温度和感染蚊龄对菌泡(无性期)和卵孢子(有性期)形成的影响。将保存在培养基上的真菌接种到盛去离子水的盆中诱发形成大量菌泡和游动孢子,选用4个龄期的致倦库蚊幼虫分别放入具有大量游离孢子(10~(?)/ml)的盆中,2h后将幼     

不同日龄致倦库蚊对马来丝虫易感性的比较研究

不同日龄致倦库蚊分别经胸内接种马来丝蚴后，比较观察了蚊虫体内微丝蚴的黑化率、三期幼虫率以及感染性蚊虫的比率，接种后第３、４、５、９ｄ解剖接种蚊虫，结果表明，１－２日龄蚊虫体内微丝蚴黑化率显著高于１５－１６日龄蚊虫，分别为８４．１和５７．５％。三期幼虫率则相反，分别为１．５％和３．７％。黑化的微丝蚴主要分布在蚊虫腹。占７２．３％和６９．１％。     

Effects of culture medium and formulation on the larvicidal activity of the mosquito pathogen Lagenidium giganteum (Oomycetes: Lagenidiales) against Aedes aegypti

In this work, we examined the production of infective zoospores of Lagenidium giganteum in four culture media, and the larvicidal activity of the cultures was determined against Aedes aegypti larvae, as well as the effect of polymer encapsulation. Medium containing sunflower seed extract showed the greatest production of zoospores, 5.92 × 10⁶ zoospores/ml after six days of fermentation at 25 ± 2 °C and 150 rpm shaking. This culture tested against A. aegypti 1st stage larvae caused different mortality rates at 24, 48 and 72 h posttreatment. The LC₅₀ obtained was 43.9, 41.1 and 42.9 μl of total culture/ml, at 24, 48 and 72 h posttreatment respectively, while the culture grown in medium with soybean meal showed 3–5 times higher LC₅₀ values. Finally, the total culture including mycelium, zoospores and presporangia formulated with 2.5% pectin showed significantly higher mortality rates, around 100% more than the unformulated culture, whose values were from 40 to 1% at 3, 6, 9, and 12 d posttreatment in the bioassays carried out in the laboratory to determine residual activity.     

Seasonality of adult Culex quinquefasciatus and transmission of bancroftian filariasis in Pondicherry, south India.

Seasonal variations in biting Culex quinquefasciatus and transmission of bancroftian filariasis were investigated in Pondicherry, South India. The biting density of C. quinquefasciatus, the principal vector species, was lowest in the summer months and higher during the monsoon and winter months. The survival of the vectors as indicated by the proportion of parous mosquitoes was found to be less in the summer season. Biting mosquitoes with infective stage larvae were not encountered during the hottest months of May, June and July and the early monsoon month of August indicating seasonality of transmission. Maximum transmission took place between November and March. These findings suggest that vector control measures according to the season of transmission may produce more cost-effective results than year round control operations.     

Molecular analysis of knock down resistance (kdr) mutation and distribution of kdr genotypes in a wild population of Culex quinquefasciatus from India

Objective  To investigate the presence of knock down resistance ( kdr ) mutation, its frequency distribution in the principal vector of bancroftian filariasis, Culex quinquefasciatus from northeastern India, and to relate kdr genotypes with susceptibility and/or resistance to DDT and deltamethrin in this vectors.
Methods  Adult female mosquitoes were collected by aspiration from human dwellings in two villages, Benganajuli and Rikamari, and two military establishments, Field Units I and II. Insecticide susceptibility tests were performed following WHO methods with 4% DDT and 0.05% deltamethrin. Molecular identification of kdr mutation and genotyping of kdr locus was performed by allele-specific PCR (AS-PCR) and direct sequencing in a subset of samples.
Results  Mosquitoes were resistant to DDT and showed 11.9–41.2% mortality, whereas the knock down bioassay for deltamethrin suggests complete susceptibility to this insecticide in all study sites except Benganajuli. The result of AS-PCR confirmed the presence of three genotypes: susceptible (SS), resistant (RR) and heterozygous (SR) in the population. Genotype frequencies at kdr locus for DDT-resistant individuals conformed with the Hardy–Weinberg proportion, whereas DDT and deltamethrin susceptible individuals differed significantly ( P  < 0.05). The efficacy of AS-PCR in detecting the correct genotype was not encouraging.
Conclusions  This is the first report from India on kdr genotyping in C. quinquefasciatus , and it confirms the occurrence of kdr allele in this vector in northeastern India. This finding has serious implications for the filariasis control programmes in India.     

Characterization of knockdown resistance in DDT- and pyrethroid-resistant Culex quinquefasciatus populations from Sri Lanka

DDT and pyrethroid resistance in Culex quinquefasciatus have been previously reported in Sri Lanka, but the mechanisms involved have yet to be characterized. We report the presence of two mutant alleles of the sodium channel gene, the target site for both DDT and pyrethroid insecticides. Both mutations resulted in classic knockdown resistance (kdr) L1014F mutation because of either an A-to-T substitution or an A-to-C substitution. We developed two alternative assays to distinguish between the two mutations and used these to screen 214 individuals from nine geographic locations throughout Sri Lanka. Very high levels of kdr mutations were found throughout the country. A predominance of the A-to-C mutation was observed over the A-to-T with an average allele frequency of 50% and 2%, respectively. In addition to these non-synonymous kdr substitutions, we also found an indel (TCACA) in the intron downstream of the kdr mutation. After genotyping this indel in 136 individuals, we found no evident correlation between kdr genotypes and intronic indel. The presence of two alternative kdr mutations has implications for the reliance on single molecular diagnostics for detection of resistance in field populations. Furthermore, the high levels of these kdr mutations in C. quinquefasciatus populations throughout Sri Lanka are of concern for the future of pyrethroid-based control programmes on this island.     

Control of pyrethroid-resistant Anopheles gambiae and Culex quinquefasciatus mosquitoes with chlorfenapyr in Benin

Objective  To compare the efficacy of chlorfenapyr applied on mosquito nets and as an indoor residual spray against populations of Anopheles gambiae and Culex quinquefasciatus in an area of Benin that shows problematic levels of pyrethroid resistance.
Method  Eight-week trial conducted in experimental huts.
Results  Indoor residual spraying killed 82.9% of An. gambiae overall (mean mortality: 79.5%) compared to 53.5% overall (mean mortality: 61.7%) in the hut containing the lower dosed ITN. Analysis of data on a fortnightly basis showed high levels of mosquito mortality and blood-feeding inhibition during the first few weeks after treatment. Control of C. quinquefasciatus by the IRS and ITN interventions showed a similar trend to that of An. gambiae and though the average level of mortality was lower it was still much higher than with pyrethroid treatments against this population. Chlorfenapyr's reputation for being rather slow acting was evident particularly at lower dosages. The treatments showed no evidence of excito-repellent activity in this trial.
Conclusion  Chlorfenapyr has the potential to control pyrethroid resistant populations of A. gambiae . There is a need to develop long-lasting formulations of chlorfenapyr to prolong its residual life on nets and sprayed surfaces. On nets it could be combined with a contact irritant pyrethroid to give improved protection against mosquito biting while killing pyrethroid-resistant mosquitoes that come into contact with the net.     

Evaluation of Aedes aegypti,Aedes albopictus,and Culex quinquefasciatus Mosquitoes Competence to Oropouche virus Infection

The emergence of new human viral pathogens and re-emergence of several diseases are of particular concern in the last decades. Oropouche orthobunyavirus (OROV) is an arbovirus endemic to South and Central America tropical regions, responsible to several epidemic events in the last decades. There is little information regarding the ability of OROV to be transmitted by urban/peri-urban mosquitoes, which has limited the predictability of the emergence of permanent urban transmission cycles. Here, we evaluated the ability of OROV to infect, replicate, and be transmitted by three anthropophilic and urban species of mosquitoes, Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus. We show that OROV is able to infect and efficiently replicate when systemically injected in all three species tested, but not when orally ingested. Moreover, we find that, once OROV replication has occurred in the mosquito body, all three species were able to transmit the virus to immunocompromised mice during blood feeding. These data provide evidence that OROV is restricted by the midgut barrier of three major urban mosquito species, but, if this restriction is overcome, could be efficiently transmitted to vertebrate hosts. This poses a great risk for the emergence of permanent urban cycles and geographic expansion of OROV to other continents.     

几种人体代谢化合物诱捕致倦库蚊效果

目的评价6种人体代谢化合物在室内场所对家栖蚊虫致倦库蚊成蚊的诱捕效果。方法采用陷阱诱捕法,分别比较乙酸、丙酸、辛酸、乳酸、1-辛烯-3醇和尿素6种人体代谢化合物单组分,液态乳酸、乙酸、丙酸、辛酸和1-辛烯-3-醇分别与固态尿素等质量混合后组合物以及乳酸、尿素按不同质量比混合后组合物诱捕致倦库蚊成蚊的效果,并以脱氯自来水作为对照。结果乙酸、丙酸、辛酸乳酸、1-辛烯-3醇和尿素诱捕致倦库蚊成蚊效果均优于脱氯自来水。按1∶1质量比制备乙酸、丙酸、辛酸或1-辛烯-3-醇与尿素组合物,其诱蚊效果与各单组分比较差异均无统计学意义(P均>0.05)。按1∶1质量比制备的乳酸-尿素组合物,其平均累计诱捕量[(35.60±8.11)只]显著优于乳酸[(20.80±8.53)只]、尿素[(17.00±7.18)只]和脱氯自来水[(7.20±2.68)只](P均<0.05)。按1∶1、1∶2、1∶3、1∶4、1∶5质量比制备的乳酸-尿素组合物,其诱蚊效果均显著优于乳酸、尿素和脱氯自来水(P均<0.05);其中最优质量比为1∶4,该组合物平均累计诱捕量为(56.20±9.88)只,显著高于乳酸[(17.00±3.94)只]、尿素[(16.40±3.78)只]和脱氯自来水[(7.40±3.44)只](P均<0.05)。结论将乳酸和尿素按一定质量比制备的组合物能明显提高致倦库蚊成蚊诱捕数量;该组合物气味微弱,适合在家居办公环境使用。