Control of the haematophagous fly Hippobosca maculata, a series pest of equines, by deltamethrin.

This study reports the results of both a small-scale and a large-scale field treatment to assess control of the haematophagous fly Hippobosca maculata Leach a serious pest of equines in a stud in India using a deltamethrin based formulation, Butox. In the small-scale field trial application of 2 litres of deltamethrin at 0.001-0.003% concentration gave 90-100% control over 30 days. At 0.004% and 0.005% concentrations complete control was recorded for 45 and 90 days respectively. Mass application of 2 litres of 0.005% deltamethrin to equines and bovines controlled infestations of H. maculata for 1 year.     

Control of the haematophagous fly Hippobosca maculata, a serious pest of equines, by deltamethrin

Abstract. This study reports the results of both a small-scale and a large-scale field treatment to assess control of the haematophagous fly Hippobosca maculata Leach a serious pest of equines in a stud in India using a deltamethrin based formulation, Butox^®. In the small-scale field trial application of 2 litres of deltamethrin at 0.001-0.003% concentration gave 90–100% control over 30 days. At 0.004% and 0.005% concentrations complete control was recorded for 45 and 90 days respectively. Mass application of 2 litres of 0.005% deltamethrin to equines and bovines controlled infestations of H.maculata for 1 year.     

Deltamethrin-impregnated dog collars have a potent anti-feeding and insecticidal effect on Lutzomyia longipalpis and Lutzomyia migonei

Deltamethrin-impregnated PVC dog collars were tested to assess if they were effective in protecting dogs from sand fly bites of Lutzomyia longipalpis and Lu. migonei. A protective effect against Old World species Phlebotomus perniciosus was demonstrated before. Four dogs wearing deltamethrin collars and three dogs wearing untreated collars (not impregnated with deltamethrin) were kept in separate kennels for over eight months in a village on the outskirts of Fortaleza in Ceará, Brazil. Periodically, a dog from each group was sedated, placed in a net cage for 2 h in which 150 female sand flies had been released 10-15 min before. Lu. longipalpis were used 4, 8, 12, 16, 22, 27, and 35 weeks after the attachment of the collars. Lu. migonei were used 3, 7, 11, 15, 22, 26, and 36 weeks after attachment. During 35 weeks, only 4.1% (81 of 2,022) Lu. longipalpis recovered from the nets with the deltamethrin collared dogs were engorged, an anti-feeding effect of 96%. Mortality initially was over 90% and at 35 weeks was 35% with half of the sand flies dying in the first 2 h. In contrast, 83% of the 2,094 Lu. longipalpis recovered from the nets containing the untreated collared dogs were engorged and the mortality ranged from zero to 18.8% on one occasion with 1.1% dying in the first 2 h. Similar findings were found with Lu. migonei: of 2,034 sand flies recovered over this period, only 70 were engorged, an anti-feeding effect of 96.5%, and mortality ranged from 91% initially to 46% at 36 weeks. In contrast, engorgement of controls ranged from 91 to71% and a mortality ranged from 3.5 to 29.8%. These studies show that deltamethrin impregnated collars can protect dogs against Brazilian sand flies for up to eight months. Thus, they should be useful in a program to control human and canine visceral leishmaniasis.     

细胞色素P450基因AsCYP6Z2在中华按蚊溴氰菊酯抗性维持中的作用

【目的】探究细胞色素P450基因AsCYP6Z2是否与中华按蚊Anopheles sinensis抗拟除虫菊酯有关。【方法】克隆中华按蚊AsCYP6Z2基因的编码区。采用实时定量PCR(real-time quantitative PCR, qPCR)检测该基因在中华按蚊溴氰菊酯敏感品系(WX-LS)和抗性品系(YN-LR)雌蚊不同发育阶段的表达和在敏感品系雌蛹不同组织中的表达。雌蛹腹部后端分别在25 mg/mL溴氰菊酯溶液和纯丙酮溶液(对照)中体外培养后,采用qPCR检测AsCYP6Z2在溴氰菊酯处理组和丙酮对照组中的表达差异。于化蛹后10 h分别注射dsAsCYP6Z2(RNAi组)和dsEGFP(对照组),采用qPCR检测AsCYP6Z2在RNAi组和对照组中的表达差异;采用生物测定方法测定RNAi组和对照组中雌成蚊接触0.05%溴氰菊酯药膜1 h内的击倒率及雌成蚊接触0.05%溴氰菊酯药膜1 h并恢复24 h时的死亡率。通过分子对接预测该基因与溴氰菊酯相互作用的氨基酸残基。【结果】克隆获得了AsCYP6Z2基因(GenBank登录号： MT840336)的编码区,其开放阅读框(ORF)长1 251 bp,编码416个氨基酸,无信号肽和跨膜结构域。发育表达谱表明,AsCYP6Z2基因主要在化蛹30 h至成蚊3 h期间高表达,且抗性品系的基因表达量明显高于敏感品系的;组织表达谱显示该基因在腹部后端的表达量较高,其次是在腹部前端和胸部,在头部的表达量最低。雌蛹腹部后端在25 mg/mL溴氰菊酯溶液中培养12 h和24 h后,处理组中AsCYP6Z2的表达量相比于对照组(纯丙酮培养组)分别上调4倍和13倍。RNAi干扰AsCYP6Z2后,RNAi组中AsCYP6Z2基因的表达量相较于对照组(dsEGFP注射组)下调了约80%。雌成蚊接触0.05%溴氰菊酯药膜1 h后,RNAi组中的个体比对照组中的约提前20 min出现明显的击倒现象,且击倒率明显高于对照组;雌成蚊接触0.05%溴氰菊酯药膜1 h并恢复24 h后,RNAi组中的个体死亡率相比对照组增加了17%, 表明沉默AsCYP6Z2基因导致蚊虫对溴氰菊酯的敏感度显著增加。溴氰菊酯与AsCYP6Z2预测蛋白的分子对接研究结果显示,溴氰菊酯可以进入AsCYP6Z2蛋白的结合口袋,并且与Cys-155形成Pi-硫相互作用以及产生较稳定的氢键,侧链也可与AsCYP6Z2的Ala-165, Val-72, Leu-76, Leu-82和Ala-24等氨基酸残基形成稳定的疏水相互作用网络。【结论】研究结果表明AsCYP6Z2基因参与中华按蚊溴氰菊酯抗性表型的维持,这为进一步探究该基因在拟除虫菊酯类杀虫剂代谢过程中的分子机理奠定了前期基础。     

Effects of insecticide sublethal concentrations on the ringlegged earwig, Euborellia annulipes (Lucas)

Integrated pest control of the sugarcane stem borer (SSB), Chila infuscatellus, recommends the use of a voracious predator as the ring legged earwig (RE), Euborellia annulipes (Lucas) and insecticide application. This study was conducted to determine sublethal effects of two recommended pyrethroid insecticides, cypermethrin and deltamethrin, on predation, the number of eggs/batch, % egg hatch and the developmental period of the offspring of RE adults. Sublethal concentrations of cypermethrin (10% EC) and deltamethrin (3% EC) at LC1 and LC10 were topically applied with a micro-applicator on tested individuals with direct and indirect methods. They were applied directly once on adults of RE or on ten 3rd instar larvae of SSB which were then fed to RE adults. Surviving adults were further investigated. Insecticide-treated RE adults with LC1 and LC10 of cypermethrin showed significantly slower onset of predation averaged 14.20 and 18.35 h, lower number of preys killed, averaged 4.8 and 4.2 larvae/d, respectively, as compared to those of untreated ones. The corresponding figures of treated adults with deltamethrin were 30.5 and 42.2 h, 4.6 and 3.8 larvae/d respectively. Similar results were obtained on RE adults that fed on insecticide-treated 3rd instar SSB larvae with the same concentrations of insecticides. The only different result was recorded on the number of preys killed by indirectly treated adults with LC1 of cypermethrin and deltamethrin averaged 9.6 and 8.8 larvae/d, respectively, which was not significantly different as compared to those of untreated ones. Insecticide-treated RE adults with LC10 of cypermethrin and deltamethrin showed significantly lower number of eggs/batch averaged 31.4 and 27.4 eggs, lower % egg hatch averaged 29.8 and 31.7%, prolonged developmental period of the offspring averaged 91.8 and 113.0 d, respectively, as compared to those of untreated ones. The corresponding figures of those from RE adults that fed on insecticide-treated 3rd instar SSB larvae were 30.7 and 37.5 eggs, 36.1 and 32.8%, 95.6 and 113.7 d, respectively, as compared to those of untreated ones. This study concluded that sublethal concentrations of cypermethrin and deltamethrin at LC1 and LC10 which did not kill RE adults reduced their predation, lowered the number of eggs/batch and % egg hatch, and prolonged the developmental period of their offspring. It is suggested that RE may not be totally safe for combination use with cypermethrin and deltamethrin in controlling SSB.     

Toxicity of Selected Insecticides to the Spined Soldier Bug, Podisus maculiventris (Heteroptera: Pentatomidae)

Susceptibility of Podisus maculiventris to the insect growth regulator teflubenzuron, the carbamate methomyl, the pyrethroid deltamethrin, and the bioinsecticide Bacillus thuringiensis subsp. kurstaki (Bactospeine) was evaluated in the laboratory. Newly-moulted fourth instars and seven-day-old female adults were exposed to formulated materials of each compound via ingestion for 48 h. Teflubenzuron was highly toxic to fourth instars (LC 50 = 14.7 mg a.i. l -1 ) of the predator, but proved to be harmless to female adults. Both fourth instars and females suffered the highest mortality when they were exposed to methomyl (LC 50 = 5.4 and 10.6 mg a.i. l -1 , respectively). Deltamethrin was relatively safe for the predator in either stage; however, fourth instars were more tolerant to the pyrethroid than females (LC 50 = 158.8 and 43.4 mg a.i. l -1 , respectively). Neither fourth instars nor females were affected by B. thuringiensis at 10 000 mg formulated material l -1 . Reproductive capacity of the predator was also examined when applying field concentrations of teflubenzuron (200 mg a.i. l -1 ) or deltamethrin (12.5 mg a.i. l -1 ) via ingestion. Treatment with deltamethrin only prolonged preoviposition period. A marked decline in egg hatch was observed when the insects were exposed to teflubenzuron compared with the control (7 vs 63%, respectively). Fourth and fifth instars that had ingested sublethal doses of teflubenzuron demonstrated longer developmental times than did those of the control. Ingestion experiments suggest that use of deltamethrin and B. thuringiensis may be compatible with releases of P. maculiventris . In contrast, populations of the predator may be harmed when methomyl or teflubenzuron are applied.     

Field Survey of Insecticide Resistance in Haematobia irritans exigua de Meijere (Diptera: Muscidae)

A survey of farms in northern New South Wales and southeastern, central, western and northern Queensland was conducted to determine levels of insecticide resistance in populations of buffalo fly Haematobia irritans exigua. A field bioassay using discriminating concentrations of 10 insecticides commonly used for buffalo fly control was used. Resistance to all synthetic pyrethroids tested (cypermethrin, deltamethrin, cyhalothrin, flumethrin and cyfluthrin) was common and widespread in coastal zones, but was lower in inland zones. In contrast, there was no resistance to the organophosphate diazinon and only low levels of resistance to ethion and chlorfenvinfos. Synergism between piperonyl butoxide and cypermethrin was demonstrated.     

Biological Control of the Shore Fly (Scatella tenuicosta) with Steinernematid Nematodes and Bacillus thuringiensis var. thuringiensis in Peat and Rockwool

Steinernema feltiae Filipjev and S. carpocapsae Weiser (Nematoda: Steinernematidae) at rates of 1, 5 and 20 million m^-2 in peat pots and at rates of 1, 2.5 and 5 million m^-2 in rockwool cubes were tested against the shore fly Scatella tenuicosta Collin (Diptera: Ephydridae) by applying the nematodes either preventatively 2 days before or curatively 9 days after, or both 2 days before and 9 days after exposing the pots and cubes to flies. Based on cumulative fly numbers that emerged from peat pots sampled weekly for 3 weeks, all application strategies with 5 or 20 million nematodes net-m^-2, irrespective of species, reduced fly numbers by 61-96% as compared to untreated controls. High temperatures in 1 week reduced control efficacy to 30-35% in some treatments. In rockwool, maximum control efficacies of 83-84% were achieved by both species in the second week in treatments that had received two applications at the rate of 5 million m^-2, but these did not differ significantly from the 69-75% efficacies achieved with 2.5 million nematodes m^-2. The cumulative control efficacy over 4 weeks was only 46% at maximum. The lower control efficacy in rockwool compared to peat was due to rapid disappearance of nematodes from rockwool.     

Topical treatment of calves with synthetic pyrethroids: effects on the non-target dung fly Neomyia cornicina (Diptera: Muscidae)

Dung from calves treated with synthetic pyrethroids negatively influenced, in varying degrees, survival, reproduction and size of the common dung fly Neomyia cornicina (Fabricius). This was documented in assays where the coprophagous larvae and adults of N. cornicina were exposed to dung collected from calves dosed with topical preparations of deltamethrin, flumethrin, cyfluthrin, and alpha-cypermethrin. Larval mortality was significantly increased in dung collected up to at least seven days after treatment with deltamethrin, alpha-cypermethrin and cyfluthrin. Alpha-cypermethrin caused significant mortality of adults allowed to feed on moist dung. Nulliparous flies fed for six days on dung collected three days after treatment of calves with alpha-cypermethrin or deltamethrin showed little or no ovarian development. A tendency for a comparable effect with flumethrin was also observed. A connection between ovarian development and inhibition of feeding was indicated by the observation of significantly lowered excretion rates in flies exposed to residues of deltamethrin, alpha-cypermethrin and flumethrin. Larvae that survived exposure to dung from calves dosed with deltamethrin, alpha-cypermethrin, or cyfluthrin gave rise to smaller flies. The effect on adult fly size decreased when larvae were exposed to dung collected at longer times after treatment of the calves. Adult fly size was significantly reduced in dung collected up to 14 days (alpha-cypermethrin) or up to 28 days after treatment (deltamethrin and cyfluthrin). Fluctuating asymmetry of a wing vein character did not reflect the anticipated levels of exposure. The study strongly indicated that the use of synthetic pyrethroids affected the insect dung fauna and that such use may reduce dung decomposition.     

Farm-scale trials to compare the entomopathogenic fungus Beauveria bassiana with pirimiphos methyl + deltamethrin and essential oil of lemon grass for protection of stored cowpea against Callosobruchus maculatus (Coleoptera: Bruchidae)

In trials conducted in Benin, conidia of Beauveria bassiana were evaluated as a control method against the cowpea weevil, Callosobruchus maculatus , in stored cowpea. In the first trial using a high artificial infestation of C.   maculatus in 8-kg batches of cowpea in jerry cans under typical conditions, concentrations of 1 × 10⁹ and 1 × 10¹¹ conidia kg⁻¹ were compared with lemon grass oil at 2 mL kg⁻¹ and the synthetic pesticide mixture of 1.5% pirimiphos methyl + 0.05% deltamethrin at 0.5 g kg⁻¹. After 2 months of storage, seed losses (SD) were 20.63 (5.3)% in the untreated control, 8.04 (3.2)% in the low-dose B.   bassiana group, 3.12 (1.3)% in the high-dose B.   bassiana group, 2.52 (0.4)% in the lemon grass oil group and 0% in the pirimiphos methyl + deltamethrin group. In a second trial with natural infestations in 50-kg batches of cowpea in 200-L drums, treatment with B.   bassiana 1 × 10¹¹ conidia kg⁻¹ was compared with pirimiphos methyl + deltamethrin at 0.5 g kg⁻¹. After 6 months of storage on six farms, losses reached 30.76 (1.5)% in the control, 1.28 (0.2)% in the pirimiphos methyl + deltamethrin group and 3.69 (0.6)% in the B.   bassiana group.     

四种基质表面上常规杀虫剂对四纹豆象的药效评价（英文）

在害虫治理中, 在消费或贮藏粮食加工产品的建筑设施或场所进行害虫防治需要将杀虫剂施用在各种基质表面上。为了测定不同基质表面上杀虫剂的药效, 将四纹豆象Callosobruchus maculatus (F.)成虫接触田间推荐剂量的阿维菌素、 溴氰菊酯和毒死蜱。结果表明： 施用在玻璃、 瓷砖、 塑料和纸盘表面上, 阿维菌素对四纹豆象成虫的致死率分别为63.33%, 22.41%, 12.9%和11.9%, 而溴氰菊酯在这4种基质表面上对四纹豆象成虫的致死率分别为 55%, 44.2%, 41.3%和 37.4%。在所有基质表面上接触毒死蜱, 四纹豆象成虫的死亡率均为100%。对数据进行的Probit 分析表明, 毒死蜱制剂在玻璃、 瓷砖、 塑料和纸盘上对四纹豆象成虫 的LC₅₀ 值分别为 8.66, 13.6, 29.16和 56.5 μg/mL, 阿维菌素制剂的相应数值分别为119.4, 446.2, 774.2 和 836.4 μg/mL, 溴氰菊酯制剂的相应数值分别为 1 008, 1 131, 1 210和 1 336 μg/mL。据此推断, 毒死蜱对四纹豆象的毒性最强, 且在玻璃、 瓷砖、 塑料和纸盘表面上的毒性依次降低。     

Field efficacy of deltamethrin for rodent flea control in San Bernardino County, California, USA.

A study was conducted to determine the initial and residual activity of deltamethrin (0.05% dust) applied to rodent burrows (at approximately 14 g/burrow) against fleas in the Silverwood Lake area of San Bernardino County. In initial toxicity (2-d post-treatment), deltamethrin provided 97% flea control and in residual toxicity it resulted in 68% control of the rodent fleas at 15-d post-treatment. The flea fauna consisted of Oropsylla montana (89.9%) and Hoplopsylls anomalus (10.1%). All rodents captured in this study were California ground squirrels, Spermophilus beecheyi. In mark-release-recapture trials, using the microchip identification implant method at the treatment site, the recapture rate of rodents was 29% from 2- to 58-d post-treatment, declining to 21% after 98 d. In the tail-clip method at the treatment site, the recapture rate of 40% at 15-d post-treatment rose to 87% and 73% at 56- and 58-d post-treatment, respectively. At the control site, the recapture rate of 100% at 15-d post-post-treatment dropped to 20% after 98 d. In another trial at Camp Cedar Crest in the Running Springs area, deltamethrin applied to rodent burrows resulted in 70% control of fleas infesting S. beecheyi. Based on the two trials, deltamethrin showed a good initial control of rodent fleas in enzootic or epizootic plague control.     

溴氰菊酯对黄瓜幼苗过氧化氢酶活性的影响

用100mgL-1的溴氰菊酯喷施黄瓜幼苗2d后,体内过氧化氢酶活性升高49．65％．150mgL-1的溴氰菊酯使体内蛋白质含量升高33．25％,使DNA和RNA含量分别上升15．39％和11．49％．而500mgL-1的溴氰菊酯却使过氧化氢酶活性降低6．94％,蛋白质、DNA和RNA含量分别降低10．22％、9．85％和16．20％．溴氰菊酯对高体的过氧化氨酶活性无影响．放线菌酮对溴氰菊酯影响蛋白质含量和过氧化氢酶活性有抑制作用．初步讨论了低浓度溴氰菊酯影响过氧化氢酶活性的可能原因．     

星豹蛛四个羧酸酯酶基因克隆及溴氰菊酯胁迫下的表达模式

【目的】探究星豹蛛Pardosa astrigera羧酸酯酶基因PaCarE1-4是否与其代谢溴氰菊酯有关。【方法】采用RT-PCR技术克隆星豹蛛4个羧酸酯酶基因PaCarE1-4 cDNA序列,通过生物信息学软件分析其序列特性。采用RT-qPCR技术测定这4个羧酸酯酶基因在星豹蛛雌雄成蛛不同组织(头胸部、腹部和足)以及在不同浓度(LC₁₀=5.151 mg/L; LC₃₀=8.619 mg/L; LC₅₀=12.311 mg/L)溴氰菊酯胁迫12 h和LC₃₀浓度溴氰菊酯胁迫2, 4, 8, 12, 24和48 h雄成蛛中的相对表达水平。【结果】克隆获得星豹蛛羧酸酯酶基因PaCarE1-4(GenBank登录号分别为MZ643212, MZ643214, MZ643215和 MZ643216)的全长cDNA序列,开放阅读框(ORF)分别长1 653, 1 803, 1 827和1 818 bp,分别编码550, 600, 608和605个氨基酸。组织表达谱结果表明,PaCarE1和PaCarE2在星豹蛛雌雄成蛛腹部中的表达量最高,且在雄成蛛腹部中的表达量高于雌成蛛中的;PaCarE3和PaCarE4在雌雄成蛛头胸部中的表达量最高,且PaCarE3在雌成蛛头胸部中的表达量高于雄成蛛中的,PaCarE4在雄成蛛头胸部中的表达量高于雌成蛛中的。LC₃₀浓度溴氰菊酯胁迫12 h诱导了星豹蛛雄成蛛中PaCarE1的表达,LC₁₀和LC₃₀浓度溴氰菊酯胁迫12 h诱导了PaCarE2的表达。LC₃₀浓度溴氰菊酯胁迫不同时间后,与对照组(丙酮处理组)相比,星豹蛛雄成蛛中PaCarE4的表达量与对照组均无显著差异,而PaCarE1的表达量在处理后2, 8和12 h, PaCarE2的表达量在处理后12 h,以及PaCarE3的表达量在处理后24 h显著上调。【结论】羧酸酯酶基因PaCarE1, PaCarE2和PaCarE3可以被溴氰菊酯诱导表达,表明其可能参与星豹蛛对溴氰菊酯的代谢过程。本研究结果有助于了解星豹蛛对外源物质的代谢机理,为这一捕食性天敌的保护提供了新思路。     

Effects of Some Pesticides on Development of Ascaris suum Eggs

To evaluate the effects of pesticides to parasite eggs, Ascaris suum eggs were incubated with 5 different pesticides (1:1,500-1:2,000 dilutions of 2% emamectin benzoate, 5% spinetoram, 5% indoxacarb, 1% deltamethrin, and 5% flufenoxuron; all v/v) at 20℃ for 6 weeks, and microscopically evaluated the egg survival and development on a weekly basis. The survival rate of A. suum eggs incubated in normal saline (control eggs) was 90±3% at 6 weeks. However, the survival rates of eggs treated with pesticides were 75-85% at this time, thus significantly lower than the control value. Larval development in control eggs commenced at 3 weeks, and 73±3% of eggs had internal larvae at 6 weeks. Larvae were evident in pesticide-treated eggs at 3-4 weeks, and the proportions of eggs carrying larvae at 6 weeks (36±3%-54±3%) were significantly lower than that of the control group. Thus, pesticides tested at levels similar to those used in agricultural practices exhibited low-level ovicidal activity and delayed embryogenesis of A. suum eggs, although some differences were evident among the tested pesticides.     

辛硫磷和溴氰菊酯混剂对家蝇抗性发展的影响

以家蝇（ＭｕｓｃａｄｏｍｅｓｔｉｃａｖｉｃｉｎａＭａｃｑｕａｒｔ）为试虫,用辛硫磷溴氰菊酯单剂及不同配比的混剂进行汰选试验。所有混剂选育的家蝇抗性发展都很缓慢,而单剂抗性发展都很快。增效试验表明,辛硫磷与溴氰菊酯混配有明显增效作用,特别是对抗性品系。生化分析结果表明,对溴氰菊酯的抗性发展与酯酶的酶活升高有关。对辛硫磷抗性发展与多功能氧化酶的酶活升高和乙酰胆碱酯酶敏感性降低有关。混剂选育的家蝇其对单剂的敏感性的变化及酶系的变化,随着混剂的配比而变化     

Impact of deltamethrin aerial sprays on adult Cyrtobagous salviniae in Botswana

The risk and effect of the insecticide deltamethrin, applied aerially in Botswana to control and eradicate tsetse fly, was studied on the non-target weevil Cyrtobagous salviniae, a biocontrol agent of the aquatic weed Salvinia molesta. Environmentally-simulated short-term toxicity bioassay used open iron cages and closed plastic basins containing weevils and salvinia placed in riverine water bodies, where they were exposed to the aerial applications of deltamethrin over the Kwando–Linyanti system in 2006. Control samples were placed 40 km outside the sprayed area. Weevil mortality, determined at 12, 36 and 60 hours after the aerial application, reached a maximum of 27%. No significant difference in mortalities was observed between the closed basins and the open cages. The amount of deltamethrin deposited at ground level was between 1.2 and 6.4 μg m^?2  and the insecticide toxicity was related to the weevil mortality. Simultaneous field monitoring through five spray applications showed that weevil abundance declined in late winter. Deltamethrin had a negligible impact on the weevil's ability to control salvinia under field conditions, probably due to the weevils’ protective mechanism and because vegetation could act as a barrier, preventing the insecticide from reaching the weevils. Minimum impacts of deltamethrin on the weevils in the present study and their recovery in the field are consistent with those of earlier spray applications in the Okavango Delta, Botswana.     

Comparative insecticidal power of three pyrethroids on netting

Adult mosquitoes, Anopheles gambiae Giles and Culex quinquefasciatus Say (Diptera: Culicidae), were exposed for 3 min to replicate samples of polyester netting cut from replicate bednets treated with pyrethroid insecticide formulations at the recommended concentration (alphacypermethrin SC at 40mg ai/m2; cyfluthrin EW at 50 mg ai/m2; deltamethrin WT at 25 mg ai/m2), or treated with only a quarter of those dosages. After 4 months domestic use of the bednets in Malawi, chemical assays showed that pyrethroid deposits on the netting were somewhat less than the target concentrations. Comparing the pyrethroid bioassay results with Anopheles at both treatment concentrations, deltamethrin gave significantly higher mortality (99.7-100%) than the other compounds (alphacypermethrin 94-96%, cyfluthrin 80-89%). Culex bioassay mortality was lower (alphacypermethrin 56-74%; cyfluthrin 63-65%; deltamethrin 50-81 %) and results with the three pyrethroid insecticides at their recommended doses did not differ significantly.     

Mutagenic evaluation of deltamethrin using rodent dominant lethal assay

The dominant lethal test was used to analyse the mutagenic potential of deltamethrin, a synthetic pyrethroid insecticide, in Swiss albino mice. In the treated series, the animals were exposed orally to three different doses (0.36, 0.72 and 1.08 mg/kg body weight) of deltamethrin dissolved in corn oil. Following the treatment, each male of control, as well as of the treated series, was mated with untreated females, every week for a period of 6 weeks. All mated females were sacrificed on the 13th day of separation and their ovaries and uterus were examined. The results revealed that deltamethrin treatment did not impair the mating capacity and fertility of Swiss albino mice. Mutagenic index, pre- and post-implantation losses were assessed. No significant pre-implantation losses were observed either weekly or averagely. Post-implantation losses were observed at medium and high doses of deltamethrin. A slight increase in dominant lethal mutation rate was observed by increasing doses of deltamethrin in early weeks but decreased in later weeks, so an apparent dose response was not observed.     

Relative Efficacy of Some Insecticides Against Brinjal Fruit and Shoot Borer,Leucinodes orbonalis Guen., and Their Impact on Fruit Yield

Six insecticides and their eight combinations were tested for their efficacy against brinjal fruit and shoot borer, Leucinodes orbonalis. Endosulfan + deltamethrin (0.07%, 0.0025%) and endosulfan + fenvalerate (0.07% + 0.005%) were highly effective against fruit borer that recorded only 13.3% damage as compared to 69.8% in control. The other promising treatments which significantly reduced the fruit damage over the control were in the order: carbaryl + fenvalerate = dichlorvos + fenvalerate (14.9%) > malathion + fenvalerate (16.4%) > fenvalerate + deltamethrin (16.6%) > dichlorvos = carbaryl + deltamethrin = malathion = dichlorvos + deltamethrin = malathion + deltamethrin (18.3%) > endosulfan (20.0%) > carbaryl (21.6%) with mean percentage of damage 14.9, 16.4, 18.3, 20.0, 21.6 and 69.8%, respectively. Carbaryl was least effective, but its combinations with pyrethroids were proved superior over carbaryl alone. Cost - benefit ratio ranged from a minimum of 1: 5.10 (carbaryl) to a maximum of 1: 20.44 (fenvalerate). Dichlorvos + fenvalerate combination gave the highest yield of 263.45 q/ha, whereas carbaryl was least effective giving 225.7 q/ha. with a net gain of Rupees 42,443.00 (US$ 886.00) and 28,141.00 (US$ 587.49), respectively. The other treatments were intermediate between the two insecticide regimes. However, all the treatments were superior over the control which produced 113.58 q/ha with a net gain of Rupees 340.00 only.