两种色型黄粉虫酚氧化酶原的cDNA克隆、生物信息学分析及表达水平检测

酚氧化酶是黑色素合成和昆虫免疫的关键酶, 通常以无活性的酚氧化酶原形式存在。为给黄粉虫Tenebrio molitor遗传分化和免疫防御研究提供参考, 本研究采用PCR和RACE技术克隆了黄、 黑两种色型黄粉虫幼虫的酚氧化酶原基因Tm-ppo, 对其cDNA序列及其推导的氨基酸序列进行生物信息学分析, 采用实时荧光定量PCR检测其在两种色型黄粉虫不同发育阶段mRNA表达水平上的动态变化。结果表明： 从黄、 黑两种色型黄粉虫幼虫中克隆出的两个Tm-ppo cDNA序列全长均为2 199 bp, 碱基序列一致性为99%, 包含一个2 055 bp的开放阅读框, 编码684个氨基酸, 它们的编码蛋白有3个氨基酸差异： 第176位（P→A）、 256位（V→A）和648位（I→M）。这两个基因分别被命名为Tm-ppo-1和Tm-ppo-2 （GenBank登录号分别为JX987235和JX987234）。 Tm-ppo-1和Tm-ppo-2编码的酚氧化酶原异构体蛋白（分别为Tm-PPO-1和Tm-PPO-2）存在一个可能的酚氧化酶原水解活化位点（R50~F51残基之间）和一个双铜结合中心（第196~239位残基和第344~411位残基）; 同时含有一个类似巯基酯区域的序列（第579~588位残基）及一个C 末端保守基序（第634~645位残基）; 但它们无氨基端疏水信号肽序列, 也不存在跨膜区域。Tm-PPO-1和Tm-PPO-2的二级结构由大量的α 螺旋、 β-折叠和无规则卷曲组成; 三级结构分为前导域（第16~66位残基）、 不相邻的功能域Ⅰ（第3~15位残基和第67~181位残基）、 功能域Ⅱ（第182~419位残基）和功能域Ⅲ（第420~679位残基）4部分。此外, Tm-ppo-1和Tm-ppo-2在黄、 黑两种色型黄粉虫的各发育期均有表达, 并且不同发育阶段的mRNA表达水平呈现明显的变化规律： 幼虫期﹥成虫期﹥蛹期。同时, 环境温度对Tm-ppo-1和Tm-ppo-2的mRNA表达具有显著影响： 与常温对照组（25~30℃）相比, 42℃暴露24 h和48 h的两种色型黄粉虫幼虫、 蛹和成虫的mRNA表达量明显下调。相同试验条件下, 黑色型黄粉虫幼虫和成虫的Tm-ppo-2 mRNA表达量明显高于黄色型幼虫和成虫的Tm-ppo-1 mRNA表达量, 但两种色型黄粉虫蛹的Tm-ppo异构体表达量无显著差异。本研究为进一步探讨黄粉虫的遗传分化和免疫防御提供了有益参考。     

两种色型黄粉虫抗冻蛋白cDNA克隆、序列分析与表达分析

产生抗冻蛋白(antifreeze proteins, AFPs)是大多数昆虫抵抗低温的一个重要策略。为给黄粉虫Tenebrio molitotr耐寒机理研究提供参考, 本研究采用RT-PCR、 5′ RACE和3′ RACE法克隆了黄、 黑两种色型黄粉虫幼虫的抗冻蛋白基因Tm-afp, 分析了其基因序列及所编码的氨基酸序列, 并检测了其在这两种色型间的mRNA水平差异。结果表明： 从黄、 黑两种色型黄粉虫幼虫克隆出的Tm-afp cDNA全长分别为579 bp和588 bp, 它们包含一个20 bp的5′端非翻译区、 一个402 bp的开放阅读框和一个变异较大的3′ 端非翻译区, 其碱基序列一致性为95%。由于这两个抗冻蛋白基因编码的蛋白成熟肽存在两个氨基酸差异： 第35位（D→E）和130位（T→S）, 因此将其判定为黄粉虫抗冻蛋白基因Tm-afp的两个异构体, 并分别命名为Tm-afp-1和Tm-afp-2。Tm-afp-1和Tm-afp-2编码的抗冻蛋白异构体（分别为Tm-afp-1和Tm-afp-2 ）信号肽之间有3个氨基酸差异： 第2位（G→A）、 9位（S→T）和27位（Y→N）; 其成熟肽的第一个氨基酸为谷氨酰胺, 含8个高度保守的12 aa短串联重复序列, 每个重复序列的第2位和第8位为半胱氨酸。此外, Tm-afp-1和Tm-afp-2均属富含苏氨酸和半胱氨酸的昆虫抗冻蛋白, 其二级结构均由大量的β-折叠和无规则卷曲组成, 三级结构为8个特殊的右手β-螺旋, 每一圈螺旋由12个氨基酸组成; 在β-螺旋的一个侧面规则排列着由保守XCT形成的β折叠片层。同时, 低温可以诱导黄、 黑两种色型黄粉虫Tm-afp的表达, 但长时间低温诱导下黑色型黄粉虫幼虫的Tm-afp表达量显著高于黄色型黄粉虫幼虫Tm-afp表达量。结果提示, 黄粉虫种内不同色型间, 抗冻蛋白基因Tm-afp可能存在多种异构体, 并且黑色型黄粉虫Tm-afp比黄色型黄粉虫Tm-afp对低温的应答更强烈。这一研究结果为进一步探索黄粉虫的耐寒性机理提供了有益参考。     

中华锐缘蜱成虫和若虫的形态(蜱总科:软蜱科)

中华锐缘蜱Argas(Carios)sinensis(1982),是我们根据幼虫形态发表的一个软蜱新种。幼虫虽已报道,但成虫和若虫形态尚未描述。研究该虫生活史,发现若虫蜕变具有2—4个龄期。本文以培养所得各龄期的若虫皮和成虫为材料进行观察作出描述。包括三个不同发育型的若虫标本18只[Ⅰ(4龄)型♀、♂各4只共八只,Ⅱ(3龄)型♀、♂各3只共6只和Ⅲ(2龄)型♀、♂各2只共4只],成虫标本6只(Ⅰ、Ⅱ、Ⅲ型♀、♂各1只)。标本制作方法,先在双管解剖镜下,将若虫皮从侧缝处用解剖针撕成背面和腹面,制成干整装片后再以霍氏(Hoyer’s)液封装,成虫则置于乳酸中处理,用解剖针撕成背面和腹面,并以霍氏液封装。     

稀土氧化镧对黄粉虫生长发育和繁殖的影响

制备每kg麦麸分别含10,20,30,40,50,60,100,150,200和300mg氧化镧的饲料,用这10种剂量的饲料分别连续饲喂1日龄的黄粉虫TenebriomolitorL.幼虫和成虫。用40mg氧化镧kg麦麸的剂量处理79d后幼虫体重比对照组增加43%,同样的剂量使产卵高峰期的雌虫日平均产卵量增加59%,是最佳的处理剂量。自1日龄起连续取食50d最佳剂量氧化镧的幼虫,体内蓄积有0.4%的镧元素。用最佳剂量氧化谰处理黄粉虫在经济上具有很高的投入-产出比。     

斑痣悬茧蜂寄生对甜菜夜蛾幼虫取食和食物利用的影响

为研究甜菜夜蛾Spodoptera exigua幼虫被斑痣悬茧蜂Meteorus pulchricornis寄生后的取食以及食物利用情况,在室内采用重量法测定了甜菜夜蛾4龄幼虫被寄生后取食量、体重增加量、营养指标的变化。结果表明：被寄生甜菜夜蛾幼虫的取食量、生长率和食物利用效率等明显受到抑制,幼虫被寄生后第3-6 d 取食量显著小于未被寄生幼虫,寄生后第4 d 的幼虫取食量只有正常幼虫的29.89%,第5 d只有48.69%。幼虫在寄生后的第3-5 d体重增加量显著小于未被寄生幼虫,分别为正常幼虫的21.51%,38.87%和14.42%,相对生长率则也显著低于后者。被寄生甜菜夜蛾幼虫的营养利用表现也明显不同于未被寄生幼虫,反映生长和代谢效率的食物利用率（ECI）和食物转化率（ECD）均显著降低,而反映吸收效率的近似消化率（AD）则提高。虽然在寄生后第4 d出现了相反的现象,其原因可能在于第4 d取食量明显减少,而体重仍在增加。本研究表明,斑痣悬茧蜂寄生明显抑制寄主甜菜夜蛾幼虫的取食、食物利用效率和生长。     

叉角厉蝽对冷冻饲料黄粉虫蛹的适应性研究

叉角厉蝽Eocanthecona furcellata是农林业重要的天敌昆虫,其替代饲料黄粉虫蛹在饲养中常出现蛹期较短、蛹量过剩的问题。为提升黄粉虫蛹的利用效率,本文探究了-18℃冷冻蛹作为叉角厉蝽饲料可行性,测定了不同冷冻时间处理（1~180 d）后其营养成分的变化,通过计算营养摄入量与种群生命表构建,评价冷冻蛹作为替代饲料与黄粉虫幼虫和活蛹的繁育效果。结果发现,-18℃冷冻30 d以上会显著降低黄粉虫蛹的蛋白质和脂肪含量。取食冷冻蛹的叉角厉蝽种群,除成虫前期显著延长外,其余生物学指标与取食活蛹条件下无显著差异;与取食幼虫的种群相比,其净生殖率R0（94.60头）、周限增长率λ（1.1111 d-1）和内禀增长率r（0.1053 d-1）更高。研究表明经-18℃冷冻7~14 d的黄粉虫蛹仍具有较高的营养价值,叉角厉蝽对其有较好的摄食和繁殖适应性,适度冷冻储存黄粉虫蛹可以用于叉角厉蝽的替代猎物。研究结果为叉角厉蝽的规模化和标准化繁育提供理论依据。     

人工饲料饲养的叉角厉蝽对昆虫的捕食能力评价

叉角厉蝽Eocanthecona furcellate(Wolff)是广泛分布于热带亚热带地区的一种重要捕食性天敌昆虫。为评估人工饲料饲养的叉角厉蝽的捕食能力,在实验室采用捕食功能反应的方法,以黄粉虫作为中介猎物饲养的叉角厉蝽为对照,评价了人工饲料饲养的叉角厉蝽3龄若虫、5龄若虫以及雌成虫对黄粉虫Tenebriomolitor(L.)幼虫及斜纹夜蛾Spodoptera litura(Fabricius)3龄幼虫、5龄幼虫的捕食效能。结果表明,两种饲料饲养的不同虫态叉角厉蝽的捕食量均随着猎物密度的增加而上升,当猎物密度增加到一定水平,捕食量趋于稳定,其捕食功能反应均符合HollingII模型。人工饲料组饲养的各虫态叉角厉蝽与对照组的对黄粉虫幼虫的捕食量没有明显差异;在饱和猎物密度条件下,人工饲料饲养的叉角厉蝽3龄若虫、5龄若虫以及雌成虫对斜纹夜蛾3龄幼虫的日最大捕食量分别为7.20、9.20、14.60头,对斜纹夜蛾5龄幼虫的日最大捕食量分别4.20、5.80、6.20头,均略低于对照组,但从取食猎物数量上来看,仍保持较强的捕食能力。     

油菜蚤跳甲成虫趋色性观察

油菜蚤跳甲PsylliodespunctifronsBaly是我县十字花科作物的主要害虫之一。1992年春作者对该虫成虫趋色性进行了观察。选用白、黄、蓝、黑色涤良、黄、红绸及白棉纱布共7种织物（面积各为33X33cm），间隔33cm悬挂在1．6m高的菜地旁边进行观察。发现阴、雨天各种织物均未诱到成虫，只有晴天气温达到12℃以上时（成虫开始活动以后）白、黄色涤良及黄绸3种织物能诱到成虫，其他织物均未诱到。三种能诱成虫的织物中，以白色涤良诱虫数量最多，最高可达164头，为黄色涤良（2头）的82倍，为黄色绸布（17头）的。65倍。从时间分析，以17～19时诱…     

饲喂浮萍对黄粉虫生长发育及繁殖的影响

为探索浮萍Lemna minor生物质利用新途径,解决浮萍在污水中引起的二次污染现象,本研究利用黄粉虫Tenebrio molitor L.食性杂,易饲养,可转化利用多种有机生物质资源的的特性,将浮萍烘干、磨碎后,与麦麸配制成50%浮萍∶50%麦麸,60%浮萍∶40%麦麸,70%浮萍∶30%麦麸,80%浮萍∶20%麦麸不同比例的混合饲料(加水使饲料含水量保持为18%)来饲养黄粉虫幼虫(以纯麦麸为对照组);同时以浮萍替代豆饼作为添加料,按照白菜∶麦麸∶浮萍=10∶4∶1做成混合饲料饲养成虫,来研究浮萍对黄粉虫生长发育及繁殖的影响。结果显示:与纯麦麸相比,幼虫试验中各处理组的生物量增长率、饲料利用率均降低,死亡率增高,而饲喂"50%浮萍∶50%麦麸"饲料的黄粉虫幼虫的各指标与对照组差异不显著,为最佳浮萍饲料配比;在成虫试验中,以浮萍为添加料的成虫单雌产卵量为586.33±6.84粒,成虫寿命为105.5±1.43 d,均显著高于以豆饼为添加料的对照组。本研究对利用黄粉虫转化处理浮萍的效果做出了初步评价,即黄粉虫取食转化浮萍是可行的,为浮萍的生物质利用提供参考。     

低含水量饲料对黑水虻生长发育的影响

【目的】了解低含水量饲料对黑水虻Hermetia illucens生长发育的影响。【方法】在27℃、RH 80%、光周期14L∶10D的饲养条件下,以含水量70%人工饲料饲养黑水虻为对照,比较饲料含水量降为30%和50%时黑水虻幼虫的存活率、幼虫体重、雌雄成虫体长、羽化率以及不同发育阶段持续时间等生物学参数与对照组的差异。【结果】30%和50%含水量饲料饲养幼虫平均体重与对照幼虫相比显著降低（P<0.05）,30%和50%含水量两个处理间体重亦有显著差异（P<0.05）。黑水虻幼虫不能在含水量30％的人工饲料中发育至预蛹,大部分幼虫至13 d时死亡。50%含水量饲料饲养幼虫比对照延迟5 d出现预蛹,滞后14 d结束预蛹,预蛹过程耗时18 d,比对照延长8 d;50%含水量饲料饲养雌雄虫比对照成虫体长显著缩短（P<0.05）,雌雄成虫羽化时间亦比对照延后5 d,雌雄成虫羽化历期均为18 d,比对照增加5 d;50%含水量饲料饲养黑水虻自卵孵化至蛹全部羽化为成虫所需时间比对照延长10.67 d,所需时间为55.67 d,而对照仅需45.00 d;但是50%含水量饲料饲养幼虫存活率和成虫羽化率与对照相比差异均不显著（P>0.05）。【结论】含水量低于70%的人工饲料不利于黑水虻的生长发育。     

Weight gain of the predator Podisus distinctus (Heteroptera: Pentatomidae) with combinations of the preys Tenebrio molitor (Coleoptera: Tenebrionidae) and Musca domestica (Diptera: Muscidae)

Little is known about Podisus distinctus (Stal) (Heteroptera: Pentatomidae) one of the Asopinae species with good possibilities for mass rearing and releasing against defoliator caterpillars in eucalyptus reforested areas in Brazil. We evaluated the impact of prey combinations on weight of nymphs and adults of P. distinctus. The prey were Musca domestica L. (Diptera: Muscidae) and Tenebrio molitor L. (Coleoptera: Tenebrionidae). The experiment was developed under 25 +/- 0.5 degrees C, 60 +/- 10% R.H. and photophase of 14 hr, with nymphs of P. distinctus individualized in Petri dishes and fed as: T1-larvae of M. domestica during its whole nymphal phase: T2-larvae of M. domestica during its II instar and of T. molitor during the other instars: T3-larvae of M. domestica during II and III instars and of T. molitor during the other instars: T4-larvae of M. domestica during II, III and IV instars and of T. molitor during the V instar; T5- larvae of T. molitor during all instars. P. distinctus presents lower weight when fed with larvae of M. domestica. For this reason it is recommended to feed P. distinctus with T. molitor during its whole nymphal phase or with larvae of M. domestica only during II and III instars and T. molitor during IV and V instars.     

Self-selection of two diet components by Tenebrio molitor (Coleoptera: Tenebrionidae) larvae and its impact on fitness

We studied the ability of Tenebrio molitor L. (Coleoptera: Tenebrionidae) to self-select optimal ratios of two dietary components to approach nutritional balance and maximum fitness. Relative consumption of wheat bran and dry potato flakes was determined among larvae feeding on four different ratios of these components (10, 20, 30, and 40% potato). Groups of early instars were provided with a measured amount of food and the consumption of each diet component was measured at the end of 4 wk and again 3 wk later. Consumption of diet components by T. molitor larvae deviated significantly from expected ratios indicating nonrandom self-selection. Mean percentages of dry potato consumed were 11.98, 19.16, 19.02, and 19.27% and 11.89, 20.48, 24.67, and 25.97% during the first and second experimental periods for diets with 10, 20, 30, and 40% potato, respectively. Life table analysis was used to determine the fitness of T. molitor developing in the four diet mixtures in a no-choice experiment. The diets were compared among each other and a control diet of wheat bran only. Doubling time was significantly shorter in groups consuming 10 and 20% potato than the control and longer in groups feeding on 30 and 40% potato. The self-selected ratios of the two diet components approached 20% potato, which was the best ratio for development and second best for population growth. Our findings show dietary self-selection behavior in T. molitor larvae, and these findings may lead to new methods for optimizing dietary supplements for T. molitor.     

Diet-switching by gypsy moth: effects of diet nitrogen history vs. switching on growth, consumption, and food utilization

Gypsy moth (Lymantria dispar (L.) (Lepidoptera: Lymantriidae)) larvae were reared from hatch on 1.25% N or 3.5% N artificial diet (previous diet) and switched reciprocally to the other diet (current diet) after molting into the second, third, fourth, or fifth instar. The nitrogen concentration of food consumed during previous instars had a strong residual effect on the growth rate in subsequent instars when a diet switch was made during instars two through four, but did not affect growth rate of fifth-instar larvae despite effects on food consumption and utilization. In early instars, larvae reared on 1.25% N artificial diet and then switched to 3.75% N diet had lower mass-adjusted growth rates than larvae continuously reared on 3.75% N diet. Conversely, larvae reared on 3.75% N diet and switched to 1.25% N had higher mass-adjusted growth rates than larvae reared continuously on 1.25% N diet. Relative to larvae previously reared on 1.25% N diet, fifth-instar male larvae previously reared on 3.75% N diet had slightly lower consumption rates, higher net growth efficiency (ECD), and higher gross growth efficiency (ECI). Larvae previously reared on 3.75% N diet tended to have lower food assimilation efficiency (AD) and lower nitrogen assimilation efficiency (AD(N)). Although both previous and current diet nitrogen concentration strongly affected larval growth and food utilization, the interaction term between these was not significant for any response variables except ECD and ECI. Because the interaction term reflects the effect of switching per se, the results indicate that there was a metabolic cost associated with switching, but no inherent net cost or benefit of diet-switching to growth.     

Effects of maternal diet on fecundity and larval development in the 'primitive' granivorous carabid Amara (Curtonotus) macronota

Granivory is one of the most specialized food habits in the Carabidae and has been reported for species from the tribes Zabrini and Harpalini. Most studies of carabid granivory have been conducted using specialized granivorous species, and few have examined primitive ones. This study examined effects of maternal diet on fecundity and larval development in Amara ( Curtonotus ) macronota (Solsky) (Coleoptera: Carabidae), a member of the most basal clade of the tribe Zabrini; a previous study indicated that larvae of this species are omnivores with a tendency toward carnivory. Three diet types, Tenebrio molitor L. larvae, mixed seeds [ Bidens frondosa L. (Asteraceae), Setaria spp., and Digitaria ciliaris (Retz.) Koeler (both Poaceae)], and T. molitor larvae + mixed seeds, were used as maternal diets, and larvae were reared on T. molitor larvae + mixed seeds (optimal diet) or T. molitor larvae (suboptimal diet). Fecundity differed significantly among treatments, with individuals fed the T. molitor larvae + mixed seeds diet having the highest fecundities and the mixed seeds diet producing the lowest values. Larval development [survival and duration of development through pre-overwintering stages (first and second instars)] was not significantly affected by either maternal or larval diets, but the addition of seeds to the maternal diet had a weak negative effect on larval survival. These results are in contrast with findings from specialized granivorous carabids, in which both adults and larvae performed best with pure-seed diets. Recent molecular phylogenies indicate that these specialized granivorous carabids belong to derived lineages, while A. macronota is the most basal clade of each tribe. These results are compatible with the hypothesis that carabid granivory has evolved gradually from ancestral carnivory, with omnivorous habits occurring as a transient state.     

发酵牛粪对黄粉虫幼虫生长发育的影响

为寻找大型养殖场牛粪资源化与产业化利用途径,本文探讨了杂食性黄粉虫转化与利用牛粪的可行性.将牛粪和黄粉虫常规饲料(65％麦麸、30％玉米面、5％豆粕)按梯度比例混合后,用有益微生物菌群(EM)发酵,筛选出FD1、FD2(牛粪含量分别为60％、80％)两组发酵饲料作为处理,以常规饲料为对照(CK)进行黄粉虫幼虫饲养试验,研究不同发酵料对黄粉虫幼虫生长曲线、死亡率、化蛹率、抗氧化系统等的影响,评价黄粉虫幼虫对发酵牛粪饲料的适应性.结果表明:与CK相比,虽然FD1处理黄粉虫幼虫生长周期延长了20 d,死亡率有所上升,但黄粉虫幼虫单体取食总量增加49％ (P＜0.01),末龄幼虫单体质量增加28％(P＜0.01),粗脂肪含量提高26％(P＜0.05),不饱和与饱和脂肪酸含量的比值比CK高32％(P＜0.05),抗氧化酶活性显著增强,对发酵饲料表现出良好的适应性;而FD2处理各项指标均比CK差,表现出较低的适应性.表明在FD1处理条件下,可利用黄粉虫3龄幼虫对牛粪进行资源化利用,具有较好的应用前景.     

室内条件下莱氏猛叩甲对松墨天牛和黄粉虫的捕食能力

【目的】本研究旨在明确莱氏猛叩甲Tetrigus lewisi老熟幼虫分别对黄粉虫Tenebrio molitor和松墨天牛Monochamus alternatus末龄幼虫和蛹的捕食量的差异,评估莱氏猛叩甲的捕食能力,为松墨天牛M.alteratus的有效治理找到潜在的高效生物防治因子。【方法】于2014年11月在浙江富阳昌东村马鞍山砍下松墨天牛虫害木,通过林间野外调查,明确松墨天牛和莱氏猛叩甲的发生情况;将野外采集到的莱氏猛叩甲幼虫带回室内,分别饲喂黄粉虫和松墨天牛的末龄幼虫和蛹,每天记录捕食量,确定莱氏猛叩甲的捕食能力。【结果】野外调查中,我们在松墨天牛幼虫蛀食的坑道中发现了莱氏猛叩甲幼虫和松墨天牛幼虫被取食后的残体;在采集到1 094头松墨天牛幼虫的危害木内,共采得莱氏猛叩甲末龄幼虫36头,约为松墨天牛幼虫数量的3%。室内捕食实验表明,5 d内莱氏猛叩甲捕食黄粉虫幼虫总量为3.2头,平均每天捕食约0.6头,而捕食松墨天牛幼虫总量为8.0头,平均每天捕食约1.6头,莱氏猛叩甲对松墨天牛的总捕食量显著高于对黄粉虫幼虫的总捕食量(P0.0001);4 d内莱氏猛叩甲捕食黄粉虫蛹总量为5.6头,平均每天捕食约1.4头,而捕食松墨天牛蛹总量为7.8头,平均每天捕食约2.0头,莱氏猛叩甲对松墨天牛蛹的捕食量显著高于黄粉虫蛹(P=0.028)。回归分析还表明,莱氏猛叩甲幼虫的捕食量不受叩甲个体大小的影响。【结论】莱氏猛叩甲普遍分布在松墨天牛发生区,同时发现松墨天牛被取食后的残体,表明莱氏猛叩甲是松墨天牛的捕食性天敌。莱氏猛叩甲均能捕食黄粉虫和松墨天牛的幼虫和蛹;相比于捕食黄粉虫,莱氏猛叩甲对松墨天牛的幼虫和蛹具有更好的捕食效率,具有很好的生物防治前景,是未来松墨天牛治理潜在高效生物防治因子。     

Toxicity,persistence, and efficacy of indoxacarb on cabbage looper (Lepidoptera: Noctuidae) on cabbage

Toxicity of indoxacarb was bioassayed against eggs and young (first and second instars) and older larvae (third and fourth instars) of cabbage looper, Trichoplusia ni (Hübner), on cabbage (Brassicae oleracea variety capitata L.), and persistence of field-aged leaf residues of indoxacarb was bioassayed with second and third instars of T. ni on cabbage. Efficacies of indoxacarb and several other newer insecticides to T. ni were tested under field conditions for two seasons in south Texas. LC50 and LC90 values for T. ni eggs were relatively high, indicating that indoxacarb has little ovicidal effects on T. ni eggs. Indoxacarb was highly toxic to T. ni larvae, having low LC50 and LC90 values. Bioassays of field-aged leaf residues of indoxacarb tested in the spring of 1998 (0-, 3-, 5-, and 12-d-old residues) and the fall of 2000 (0-, 3-, 5-, 7-, 9-, and 13-d-old residues) indicated that ingesting indoxacarb was highly toxic to the second and third instars of T. ni, giving 100% mortality for the second instars at 2 d after exposure, and 100% mortality for third instars at 5 d after exposure. Two trials conducted under field conditions show that indoxacarb at 0.072 g (AI) /ha rate was effective against T. ni in cabbage, providing marketable cabbage with three applications per season. In addition, indoxacarb was as effective as spinosad and chlorfenapyr and significantly more effective than tebufenozide and emamectin benzoate.     

In-vitro assessment of food consumption,utilization indices and losses promises of leafworm,Spodoptera litura (Fab.), on okra crop

The lepidopteran insect pests have significant importance in vegetable production. The present study was performed to investigate the baseline studies about the assessment of feeding and consumption potential, utilization indices and losses promises of leafworm, Spodoptera litura (Fab.) on Okra. The data regarding feeding potential, food utilization and consumption indices as well as losses of different larval instars were recorded and subjected to appropriate statistical analysis. The results showed that, in the beginning, the approximate digestibility of various instars was increase, e.g. third instar (51.36%–64.03%), fourth instar (63.42%–69.45%) and fifth instar (70.25%–76.10%). However, after a certain period, the digestibility was decreased and efficiency to convert the ingested food into biomass varied significantly. The consumption index values increased with an increase in time but the consumption and growth rate was declined of fourth instar larvae. The ingestion and digestion increased of third (10.01–13.06, 8.32–11.91 mg), fourth (11.27–17.28, 10.96–14.03 mg) and fifth (12.60–19.40, 11.93–15.28 mg) larval instars. The corrected weight of consumed leaves increased with a gain in body weight. However, in the third instar, a decline was observed on the last day of feeding. Maximum leaf area was consumed by fifth instar larvae (44.66 cm²) followed by fourth (35.41 cm²) and third (27.98 cm²) instars. In conclusion, all the dependent parameters, including food utilization potential, consumption indices and losses were higher for fifth instar larvae than others. These results emphasized the re-establishment of fundamental (economic threshold level: ETL, economic injury level: EIL) integrated pest management concepts.