Seasonal parasitism and biological characteristics of Habrobracon hebetor (Hymenoptera: Braconidae) – a potential larval ectoparasitoid of Helicoverpa armigera (Lepidoptera: Noctuidae) in a chickpea ecosystem

Seasonal parasitism of Habrobracon hebetor (Say) on Helicoverpa armigera (Hübner) in chickpea was studied for three consecutive years. Parasitism by H. hebetor on larvae of H. armigera reached 12.3%. The parasitoid maintained reproductive activity on H. armigera from February to April coinciding with pod formation and maturation stages of the crop. In laboratory assays, we investigated the suitability of larval instars of H. armigera to the parasitoid H. hebetor. This parasitoid attacked third to sixth instars, though fourth and fifth instar larvae were found most suitable with 100% parasitism and development to adults. Parasitoid developmental time was longest in fifth instar (9.1 days) compared to other instars (8.1–8.9 days). Fifth instar larvae resulted in highest numbers of cocoons and adult emergence. In addition, suitability of seven lepidopteran species to H. hebetor was investigated. Corcyra cephalonica, Galleria mellonella and H. armigera were the most suitable hosts with 100% parasitism and development to adults. It was followed by Maruca vitrata and Autographa nigrisigna with 60–76.7% and 40–70% parasitism and parasitoid developmental success, respectively. Though there was 23.3% parasitism, there was no parasitoid development in Spodoptera litura. No parasitism was recorded in Spilarctia obliqua. Development of H. hebetor was most rapid in C. cephalonica (8.7 days), and longest in G. mellonella (9.3 days). Parasitoids that developed on these hosts resulted in highest numbers of cocoons and adult emergence. The parasitoid could be exploited for the biological control of H. armigera in a chickpea ecosystem.     

八种杀虫剂对韭菜迟眼蕈蚊发育和繁殖的亚致死效应

用胃毒触杀法确定8种常用杀虫剂对韭菜迟眼蕈蚊Bradysiaodoriphaga 3龄幼虫的LC₂₀和LC₅₀剂量后,以其LC₂₀分别处理3龄幼虫,将存活幼虫正常饲养,测定该剂量药剂对韭菜迟眼蕈蚊化蛹率、蛹重、羽化率,成虫存活率、雌雄比、单雌产卵量及卵孵化率等指标的影响。结果表明:毒死蜱等4种药剂的影响较显著,其影响程度由高到低依次为毒死蜱＞辛硫磷＞阿维菌素溴虫腈;而另4种药剂丙硫克百威、灭多威、丁硫克百威和吡虫啉则影响不显著。此外也测定了用后4种药剂LC₅₀剂量处理的存活试虫的上述生物学指标,结果表明：除化蛹率和羽化率较对照降低且差异显著外,其他生物学指标与对照处理无明显变化。     

甲氰菊酯和阿维菌素对柑橘全爪螨的亚致死效应

通过叶碟饲养的方法, 利用生命表技术,研究了甲氰菊酯和阿维菌素亚致死剂量LC₂₀处理柑橘全爪螨若螨后,对试验种群当代(F₀)和后代(F₁、F₂代)生长发育及繁殖的影响.结果表明: 甲氰菊酯LC₂₀处理若螨后,当代雌成螨产卵量显著增加;F₁、F₂代的产卵前期缩短,后代雌性比例增大,且均与对照差异显著;同时,F₁和F₂代种群内禀增长率(r_m)和周限增长率(λ)增大,世代历期(T)和种群加倍时间(Dt)缩短,且F₂代与对照相比差异显著.用阿维菌素LC₂₀处理若螨后,当代种群雌成螨产卵量显著下降; F₁和F₂代的产卵量也显著下降,但后代雌性比例增大,产卵前期显著缩短;F₁和F₂代的种群r_m和λ增大,T和Dt缩短,且F₂代比F₁代更为明显.总体来看,甲氰菊酯和阿维菌素亚致死浓度LC₂₀对柑橘全爪螨的影响并不完全相同,甲氰菊酯能够促进当代种群的发展,而阿维菌素对当代种群有一定的抑制作用;但两种杀螨剂亚致死浓度处理柑橘全爪螨对后代种群都有一定的促进作用.研究结果对柑橘全爪螨综合防治策略的制定有一定的指导意义.     

亚致死浓度氯虫苯甲酰胺可降低亚洲玉米螟的种群增长

为了探讨氯虫苯甲酰胺对亚洲玉米螟Ostrinia furnacalis (Guenée)的抗性风险评估, 为科学使用氯虫苯甲酰胺防治亚洲玉米螟提供理论基础, 本研究在实验室条件下采用饲料混毒法测定了新型杀虫剂氯虫苯甲酰胺对亚洲玉米螟的毒力, 利用生命表技术研究了氯虫苯甲酰胺对亚洲玉米螟 3龄幼虫的亚致死效应。结果表明： 氯虫苯甲酰胺对亚洲玉米螟3龄幼虫的LC₁₀, LC₄₀ 和LC₅₀分别为0.038, 0.098 和0.123 mg a. i. /L。以氯虫苯甲酰胺LC₁₀和LC₄₀剂量分别处理亚州玉米螟3龄幼虫后, 幼虫和蛹的发育历期明显延长, 成虫寿命缩短, 产卵量也显著降低, 但对蛹重（雌： P=0.337, 雄： P=0.121）、卵孵化率（P=0.087）和性比（P=0.379）无显著影响。处理种群的净增值率（R₀）、内禀增长率（r_m）和周限增长率（λ）显著低于对照种群（P<0.0001）。结果提示, 氯虫苯甲酰胺的亚致死浓度可降低亚洲玉米螟的种群增长。     

四个大豆栽培种的花序转录组分析

针对大豆落花落荚问题,选取花器官脱落性质存在差异的4份大豆(Glycine max)花序样品进行了RNA提取、转录组测序和分析。共获得原始数据20 GB,其中有效数据14.87 GB。结果表明,多荚与少荚品种花序转录水平差异主要集中在物质代谢、胁迫应答(GLYMA02g03301、GLYMA02G03230等)、刺激应答、病害抗性等方面,与脱落直接相关的基因表达上并无显著差异,表明参与上述生理过程的相关基因表达的差异与不同品种大豆落花落荚性质上的差异具有一定相关性。该结果系统地了解了不同品种大豆在花期花序部分的转录组特征与差异,分析了相关表达差异对于大豆落花落荚的影响,同时丰富了大豆转录组数据信息。     

Interaction between MbMNPV and the braconid parasitoid Habrobracon hebetor (Hym., Braconidae) on larvae of beet armyworm,Spodoptera exigua (Lep., Noctuidae)

The survival of a braconid parasitoid Habrobracon hebetor was investigated on nucleopolyhedrovirus (NPV)-infected Spodoptera exigua larvae. The second-instar larvae were exposed to 30, 51.4 and 180 PIB/mm² of Mamestra brassicae NPV (MbMNPV) as under-LD₅₀, LD₅₀ and over-LD₅₀ values, respectively. They were accessible to be parasitized by H. hebetor after 24, 48 and 72 h post-treatment. Infection of the larvae with MbNPV was deleterious to the survival and parasitism of H. hebetor. The survival of H. hebetor in MbNPV-infected S. exigua larvae was dependent on the interval between viral infection and parasitization, as well as on the treatment dose of MbMNPV; very few adults of parasitoid emerged from infected hosts when host larvae were exposed to 180 PIB/mm² of MbNPV on 72-h interval treatment. The inoculation dose of MbNPV and the timing of parasitoid release had significant effect on the development of H. hebetor on virus-infected hosts. Field applications of virus for biocontrol of S. exigua may lead to substantial mortality of immature parasitoids.     

Effect of Bacillus thuringiensis on Habrobracon hebetor during combined biological control of Plodia interpunctella

Abstract  The suitability of combining microbial pesticides and an insect parasitoid for pest management of stored cereal in China was evaluated using laboratory assays. For this purpose, interactions between Bacillus thuringiensis ( Bt ), Bt -intoxicated host larvae and the parasitoid Habrobracon hebetor (Say) (Hymenoptera: Braconidae) were tested against Plodia interpunctella Hübner (Lepidoptera: Pyralidae) . Bt or H. hebetor alone caused 41.67% and 35.35% P. interpunctella larval mortality respectively. The Bt –parasitoid combined treatment significantly increased mortality of P. interpunctella (86%). Progeny development of H. hebetor was dependent upon its susceptibility to Bt . Fewer parasitoids emerged from Bt –parasitoid combined treatment than in non- Bt treatments. However, since Bt did not prevent parasitoid development, a combined treatment with Bt and parasitoid release could produce better protection against P. interpunctella than either treatments when used singly, because their lethal effects were additive to each other.     

Sublethal toxicity of two insect growth regulators on Habrobracon hebetor (Hymenoptera: Braconidae) under laboratory conditions

The sublethal effects of lufenuron and lufenuron?+?fenoxycarb were tested on the adult stage of the parasitoid wasp Habrobracon hebetor under laboratory conditions. Bioassay tests were carried out in the incubator at a temperature of 26?±?1?°C, relative humidity of 65?±?10% and photoperiod of 16:8 (L:D). Exposure cages were used for the experiments. Tests were conducted in three replications. Young female wasps were exposed to the residues of the pesticides’ sublethal concentrations (LC₂₅) after 1, 24, 48 and 72 h, and then their mortalities were recorded. Results showed that both insecticide treatments had significant differences compared to the control, but not between themselves (df?=?1, F?=?29.21, α?<?.0001). It was also revealed that the time between insecticides application and H. hebetor release would significantly affect the survival of searching parasitoids (df?=?3, F?=?237.01, α?<?.0001). In this regard, the releasing programme should be postponed for at least 24 h after using these insect growth regulators.     

不同温度对麦蛾茧蜂实验种群生长发育的影响

在15,20,25和30℃4个温度梯度下,测定了麦蛾茧蜂Habrobracon hebetor(Say)成蜂寿命、生殖力、发育历期等生物学参数。结果表明,在实验温度范围内,卵期在15℃最长,为(9.50±1.39)d;幼虫发育历期在20℃最长,为(6.60±1.41)d;蛹期在15℃最长,为(23.71±2.63)d。雌蜂的寿命在15℃时最长,为(50.15±6.9)d;30℃时最短,为(9.20±3.12)d雄蜂的寿命在15℃时最长,为(11.45±3.52)d;30℃时最短为(5.90±1.62)d。产卵量在25℃最大,为(208.50±40.12)粒;羽化数、羽化率在30℃最高,分别为(23.60±9.33)%和(35.87±13.87)%;温度变化对麦蛾茧蜂雌成蜂生物学参数具有显著影响。     

Effect of cold storage of pupae parasitoid wasp,Habrobracon hebetor (Say) (Hymenoptera: Braconidae), on its efficiency

Cold storage is an appropriate way to extend the life of natural enemies such as insect parasitoids. Identification of risk factors for use in biological control and replacing it instead of chemical control is important, and therefore wasp species of genus Bracon have been used for controlling various pests in the past and present. The aim of this study was to determine the optimum temperature and time of storage of parasitoids pupae, Habrobracon hebetor (Say) in cold conditions. After in vitro rearing of the insect, the pupae of H. hebetor at the temperatures of 12, 9 and 4?°C for a period of six weeks in five replicates were stored. After these times, the effect of storage on the percentage of emerged adults and the longevity of male and female adults was evaluated on a weekly basis. The results of the survey conducted at 12?°C showed that the percentage of adults emerged from the first week has dropped by almost half. H. hebetor pupae could be stored for a week at 9?°C. At 4?°C, a significant reduction was caused in the efficacy of the stored pupae and is not recommended.     

麦蛾柔茧蜂幼虫唾液腺的显微与超微形态观察

本文采用解剖学观察、显微摄影、透射电镜等方法对麦蛾柔茧蜂Habrobracon hebetor幼虫唾液腺的显微形态、超微结构以及发育特性进行了观察和分析。麦蛾柔茧蜂幼虫唾液腺为一对无色透明至乳白色的管状腺体,自口腔沿中肠两侧向后延伸,单侧腺体在中部先分支、后合并成一不规则环状,端部呈单盲管状。唾液腺管道长度随幼虫龄期增加而呈线性增长。对唾液腺切片进行超微结构观察,发现腺管由两类差异明显的单层细胞组成,I型细胞微绒毛层较厚,胞内除有丰富的内质网和线粒体之外,还含有大量囊泡,并观察到囊泡运输分泌颗粒的现象;II型细胞微绒毛短,胞内的内质网和线粒体数量丰富。本文研究为深入探究寄生蜂幼虫的消化生理以及寄生蜂-寄主互作机制奠定了基础。     

温度对麦蛾柔茧蜂功能反应的影响

为明确温度变化在麦蛾柔茧蜂Habrobracon hebetor对印度谷螟Plodia interpunctella寄生作用中的影响, 研究了室内17, 20, 23, 26, 29, 32和35℃条件下, 麦蛾柔茧蜂对不同密度的印度谷螟5龄幼虫的麻痹和寄生作用。结果表明: 在17～29℃范围内, 寄生蜂的寄主处理时间与温度成反比, 从17℃的0.341 d到29℃的0.068 d, 但温度再升高时, 处理时间又延长。寄主搜索率也随温度的改变而变化, 17℃时最低, 为0.056; 29℃时最高, 为1.895; 当温度升高到32～35℃时, 寄主搜索率又下降。温度调节的功能反应模型表明, 在26～29℃范围内, 寄生率较高。可见, 在26～29℃时, 麦蛾柔茧蜂对印度谷螟有较好的寄生效果, 对寄生蜂繁殖后代有利。     

阿维菌素和哒螨灵亚致死剂量对土耳其斯坦叶螨实验种群生命表的影响

为了了解阿维菌素和哒螨灵对土耳其斯坦叶螨Tetranychus turkestani Ugarov et Nikolski实验种群的亚致死效应, 为新疆土耳其斯坦叶螨的综合防治提供理论依据, 我们在室内通过叶碟饲养的方法, 利用生命表技术研究了阿维菌素和哒螨灵亚致死剂量对土耳其斯坦叶螨实验种群成螨和卵的影响。结果表明: 阿维菌素和哒螨灵LC₂₀、LC₁₀剂量处理成螨后, 可使成螨的产卵量、平均寿命和卵孵化率显著降低; 卵期、幼螨期、若螨期和产卵前期明显延长, 而成螨期和雌螨寿命又明显低于对照; 对次代种群的影响表现在净生殖率(R₀)、 周限增长率(λ)降低、生存率和平均每雌日产卵率明显降低, 内禀增长率（r_m）由0.37降低至0.17～0.29, 平均世代历期(T)除阿维菌素LC₂₀处理时长于对照外, 其他处理均低于对照, 种群倍增时间(Dt)延长。两种药剂亚致死剂量处理卵后, 内禀增长率（r_m）由0.32降低至0.11～0.22, 净生殖率(R₀)降低, 平均世代历期(T)和周限增长率(λ)降低, 而种群加倍时间(Dt)增长; 幼螨期、若螨期和产卵前期明显长于对照, 成螨期和雌螨寿命显著低于对照; 生存率和平均每雌日产雌率明显降低。这些结果证明, 在亚致死剂量下, 阿维菌素和哒螨灵能够降低土耳其斯坦叶螨种群的发育速率, 这对土耳其斯坦叶螨的综合防治策略的制定有积极意义。