Temporal host plant use in three polyphagous Heliothinae,with special reference to Helicoverpa punctigera (Wallengren) (Noctuidae: Lepidoptera)

Abstract Potential host plants of the polyphagous lepidopteran Helicoverpa punctigera (Wallengren) were surveyed in two ways. A broad survey, conducted in southern Queensland and northern New South Wales, indicated that H. punctigera larvae were present on relatively few plant species. A detailed survey of host plant use in a non-cropping area in which H. punctigera was numerous demonstrated restricted host plant use by this species. The density of H. punctigera on its principal host in the area, the indigenous daisy Ixiolaena brevicompta F. Muell., was much higher (as measured per unit of time searched) than on other plant species available. Also, I. brevicompta was used regularly by H. punctigera after rainfall events. Ixiolaena brevicompta represents a new host record and on the basis of the pattern of its use by H. punctigera should be considered a ‘primary host plant’ of this noctuid. In cropping areas sampled, usually more than one plant species hosted H. punctigera regularly and in large numbers. Usually a crop species was included (e.g. cotton and chick pea). Alternative hosts in cropping areas were Sonchus oleraceus L. (sowthistle) and possibly the native legume Sesbania cannabina (Retz.) Poiret. Our results imply that the polyphagy of H. punctigera is probably not as extensive as previously claimed. The criteria for inclusion of a plant species as a primary host for H. punctigera need to include the regularity of use of that species and the relative abundance of eggs and larvae on it. We suggest that an understanding of the host-searching mechanism of this species will be best achieved through study of the interaction of H. punctigera with its indigenous primary hosts. The surveys also yielded information on host plants of two other heliothine noctuids, H. armigera (Hübner) and Australothis rubrescens (Walker), and this is also presented.     

A simple and reliable method for discriminating between Helicoverpa armigera and Helicoverpa assulta (Lepidoptera: Noctuidae)

Abstract The cotton bollworm Helicoverpa armigera and the oriental tobacco budworm H. assulta are sibling species, both being important agricultural pests. Morphologically, the two insects are almost indistinguishable at the egg, larval and pupal stages. One of the big challenges in the study of these insects, in particular in integrated pest management, is a timely and dependable identification of these insects at their early stages of development. Here, we report a H. armigera‐specific nuclear DNA marker, and demonstrate that it can be employed to reliably discriminate between H. armigera and H. assulta by simple polymerase chain reaction amplification experiment.     

Binding of Cry δ-endotoxins to brush border membrane vesicles of Helicoverpa armigera and Helicoverpa punctigera （Lepidoptera： Noctuidae）

The relatively low susceptibility ofHelicoverpa armigera to CrylAc, its history of resistance to chemical insecticides and the seasonal decline in expression of CrylAc in transgenic cotton necessitated the development of cotton expressing two insecticidal proteins to provide sustainable control of this multinational pest. To manage the resistance issue, it was essential that the second insecticidal protein have a significantly different mode of action to CrylAc. A common feature of resistance to CrylA proteins in several species as well as H. armigera has been a change in the binding site. A study of binding sites for some Cry proteins in the brush border membrane vesicles （BBMV） ofH. armigera and Helicoverpa punctigera was undertaken. The binding affinity for CrylAc was higher than for CrylAb, matching their relative toxicities, and CrylAc and CrylAb were found to share at least one binding site in both I-1. armigera and I-1. punctigera. However Cry2Aa did not compete with CrylAc for binding and so could be used in transgenic cotton in combination with CrylAc to control H. armigera and manage resistance. Variation in the susceptibilities of three different H. armigera strains to CrylAc correlated with the parameter Bmax/Kcom.     

Aggregative oviposition behaviour of Helicoverpa spp. (Lepidoptera: Noctuidae) in contaminated chickpea crops

Abstract Aggregative egg distribution by Helicoverpa spp. within experimental field plots of chickpea containing various contaminant plant species was documented at different stages of plant growth. More eggs were laid on contaminant faba and wheat plants than on the surrounding chickpea. The level of egg aggregation on faba and wheat plants increased with general crop growth, becoming evident before a significant disparity in growth rates between these species and the surrounding chickpea became apparent. In chickpea plots contaminated with canola, aggregative oviposition activity on the contaminant plants was observed in the early seedling stage whilst a clear height differential between the two species was evident. Total Helicoverpa egg density on contaminant plants was not correlated with height above chickpea for any of the contaminant species. It is proposed that the aggregative oviposition behaviour of Helicoverpa spp. in contaminated chickpea results from differential apparency of the contaminant plants to ovipositing moths. Differential apparency may result from several factors including growth rate and morphological differences between chickpea and the contaminants. Physiological changes in chickpea, including growth stage-related changes in acid production by the foliage, may also contribute to the greater apparency of contaminant plants in chickpea plots. The implications of differential host plant apparency for insect pest management are discussed.     

Rapid antibody-based field test to distinguish between Helicoverpa armigera (Lepidoptera: Noctuidae) and Helicoverpa punctigera (Lepidoptera: Noctuidae)

Helicoverpa armigera (Hübner) and Helicoverpa punctigera (Wallengren) are the two most important insect pests of cotton production in Australia and require application of insecticides to control them. H. armigera has developed resistance to several insecticides but H. punctigera has not. Cost-effective management of insecticide resistance requires that growers be able to determine the proportion of H. armigera eggs or young larvae present on their crop before applying insecticides. This is impossible visually. We generated two monoclonal antibodies that reacted with the insect protein "lipophorin" and were capable of discriminating individuals of the two species at all life-stages. The antibodies were incorporated into a rapid test kit that was tested under field conditions over two growing seasons. Results obtained with the kit agreed closely with those obtained by rearing larvae through to second instar.     

Toxicity of Bacillus thuringiensis insecticidal proteins for Helicoverpa armigera and Helicoverpa punctigera (Lepidoptera: Noctuidae), major pests of cotton

The susceptibilities of the major pests of cotton in Australia, Helicoverpa armigera and Helicoverpa punctigera, to some insecticidal proteins from Bacillus thuringiensis were tested by bioassay. A commercial formulation, DiPel, and individual purified insecticidal proteins were tested. H. armigera was consistently more tolerant to B. thuringiensis insecticidal proteins than was H. punctigera, although both were susceptible to only a limited range of these proteins. Only Cry1Ab, Cry1Ac, Cry2Aa, Cry2Ab, and Vip3A killed H. armigera at dosages that could be considered acceptable. There was no significant difference in the toxicities of Cry1Fa and Cry1Ac for H. punctigera but Cry1Fa had little toxicity for H. armigera. The five instars of H. armigera did not differ significantly in their susceptibility to DiPel on the basis of LC(50). However, there were significant differences in the susceptibility to Cry1Ac and Cry2Aa of three strains of H. armigera. Bioassays conducted with Cry1Ac and Cry2Aa showed that there was a small but significant negative interaction between these delta-endotoxins.     

Biology and fertility life table of Helicoverpa armigera (Lepidoptera: Noctuidae) in different hosts

In 2013, the presence of Helicoverpa armigera (Hübner) was reported in cotton, soybean, corn and weeds in diverse regions of Brazil. We studied the biology and the fertility life table of this pest when reared on cotton (293 cv. CNPA RF), soybean (cv. Brasmax Power), corn (cv. BRS 1010), wheat (cv. BR 18) and on an artificial diet. Caterpillars were reared using the vegetative and reproductive structures of the hosts, under laboratory conditions (temperature 25 ± 1°C; relative humidity (RH) 70 ± 10%; photoperiod =14 h). The experimental design was completely randomized, with five treatments (four host plants and artificial diet) and 17 replications. Significant effects were verified for the different types of hosts tested on the growth of the insect as well as on fecundity and laying rate. The results showed that cotton and soybean had higher viability at the stages of growth, higher rate of survival of adult females in the reproductive period than the other host crops, and similar values for insects reared on an artificial diet, which reveals that cotton and soybean can be appropriate for rearing H. armigera on a natural diet. Corn and wheat showed high larval and pupal mortality and low biotic potential.     

Forecasting Helicoverpa populations in Australia： A comparison of regression based models and a bioclimatic based modelling approach

Abstract Long-term forecasts of pest pressure are central to the effective management of many agricultural insect pests. In the eastern cropping regions of Australia, serious infestations of Helicoverpa punctigera (Wallengren) and H. armigera (Hübner)(Lepidoptera: Noctuidae) are experienced annually. Regression analyses of a long series of light-trap catches of adult moths were used to describe the seasonal dynamics of both species. The size of the spring generation in eastern cropping zones could be related to rainfall in putative source areas in inland Australia. Subsequent generations could be related to the abundance of various crops in agricultural areas, rainfall and the magnitude of the spring population peak. As rainfall figured prominently as a predictor variable, and can itself be predicted using the Southern Oscillation Index (SOI), trap catches were also related to this variable. The geographic distribution of each species was modelled in relation to climate and CLIMEX was used to predict temporal variation in abundance at given putative source sites in inland Australia using historical meteorological data. These predictions were then correlated with subsequent pest abundance data in a major cropping region. The regression-based and bioclimatic-based approaches to predicting pest abundance are compared and their utility in predicting and interpreting pest dynamics are discussed.     

基于径向基小波网络的二代棉铃虫卵峰日预测模型

为了提高害虫预报的准确率, 将径向基小波网络首次引入农作物害虫预测预报领域, 改进了径向基小波网络的学习算法, 使之适合于害虫预测的应用: 利用径向基小波函数族时、 频两域支撑完全或部分覆盖被分析数据序列时、 频两域支撑的原理来确定小波函数族尺度参数和平移参数取值; 根据中心向量之间的欧式距离大小来初步筛选隐含层神经元。在实例分析中, 本文利用1966-1995年山东省惠民县棉铃虫Helicoverpa armigera的监测数据建立了基于径向基小波网络的2代棉铃虫卵量峰值日期预测模型, 利用1996-2000年的监测数据对模型进行了检验。检验结果表明: 在5年的预测数据中, 4年的预测数据偏差在3 d以内, 另外1年的预测数据偏差4 d, 预测效果令人满意。本文为害虫预测预报研究提供了一种可行的新方法。     

Helicostatins: brain-gut peptides of the moth, Helicoverpa armigera (Lepidoptera: Noctuidae)

Gene expression and immunolocalisation studies have determined that the helicostatins are brain-gut peptides in larvae of the lepidopteran, Helicoverpa armigera. Mapping of the distribution of these peptides in the nervous system and alimentary canal has provided evidence for multifunctional regulatory roles. In situ hybridisation studies have shown that the helicostatin precursor gene is expressed in neurones of the central and stomatogastric nervous systems, and endocrine cells of the midgut demonstrating that the helicostatins are true brain-gut peptides. Antisera raised against Leu-callatostatin 3 (ANRYGFGL-NH(2)), a peptide isolated from the blowfly, Calliphora vomitoria was used to map the distribution of allatostatin-like immunoreactive (Ast-ir) material in H. armigera to elucidate possible functions of the helicostatins. In situ hybridisation studies verified that the helicostatin precursor gene is expressed in neurones shown to contain Ast-ir, providing strong evidence that the Ast-ir material is helicostatins. Extensive immunoreactive axonal projections into complex regions of neuropile indicate that the helicostatins may have a neuromodulatory role in the brain and segmental ganglia of the ventral nerve cord. The presence of large amounts of immunoreactive material in axons within the corpora cardiaca (CC) and transverse nerves of the perisympathetic nervous system, two known neurohaemal organs, provides evidence for a neurohormonal role. The corpora allata (CA) were innervated only sparsely by Ast-ir axons suggesting that the CA are not a neurohaemal release site or a target. Thus, it is unlikely that the helicostatins regulate juvenile hormone (JH) biosynthesis or release. Ast-ir axons extended from the frontal ganglion through the recurrent nerve and many branches were closely associated with muscles of the foregut, stomodeal valve, and anterior midgut, implicating helicostatins in regulation of foregut motility. Ast-ir material was also present in nerves associated with muscles of the pyloric valve and rectum, and in endocrine cells of the midgut.     

棉铃虫围食膜的蛋白质组鉴定

【目的】围食膜(peritrophic membrane, PM)是昆虫抵御随食物摄入的病原微生物入侵的第一道天然屏障。本研究旨在鉴定出农业重大害虫棉铃虫Helicoverpa armigera围食膜的总蛋白成分,为进一步揭示昆虫围食膜的形成机制及研发新颖的害虫控制策略奠定基础。【方法】剥离棉铃虫5龄幼虫PM,用三氟甲磺酸(trifluoromethane sulfonic acid, TFMS)处理,采用液质联用技术(LC-MS/MS)鉴定围食膜蛋白质组,然后对鉴定结果进行生物信息学分析。【结果】本研究共鉴定出棉铃虫幼虫围食膜蛋白质169个,是目前鉴定最多的棉铃虫围食膜蛋白。通过GO分析,可以将这些鉴定的蛋白分为细胞组分、分子功能和生物学过程三大类;KEGG富集结果显示,鉴定蛋白可以富集在12条代谢通路中;蛋白互作分析(protein protein interaction, PPI)结果表明,以ACC和CG3011等蛋白为核心可以形成蛋白互作网络。【结论】本研究鉴定了169个棉铃虫幼虫围食膜蛋白质,并对其进行了GO, KEGG和PPI分析,结果有助于人们全面理解昆虫围食膜的分子结构和功能。     

飞行过程中棉铃虫对温度的主动选择

为了探讨温度对迁飞性昆虫空中群体聚集成层等行为的作用机制,在室内利用自行设计的连续温度梯度发生装置对棉铃虫Helicoverpa armigera在飞行过程中的温度选择行为进行了研究.结果表明：在存在明显温差的连续温度梯度中,所有棉铃虫飞行个体均对温度具有显著的选择行为.棉铃虫试虫群体表现出对空间最优飞行温度共同的主动选择,选择的温度范围是20~22℃之间;在这一温度范围内棉铃虫的振翅频率最高,持续振翅时间最长.对不同温度梯度条件下各温度区间内试虫的飞行时间进行定量比较发现,在16~22℃温度梯度场中的棉铃虫群体对最适温度的选择比在19~30℃的温度梯度场中的群体更显著,表明在温度较低的迁飞季节中温度对迁飞棉铃虫空中虫群聚集成层的影响要比在高温季节更明显.持续飞行时间对棉铃虫振翅频率的影响明显,表明昆虫迁飞高度与昆虫自身能量的消耗存在联系.     

烟青虫成虫脑结构解剖和三维模型构建

【目的】解剖分析烟青虫 Helicoverpa assulta 成虫脑的结构,并构建脑三维结构数字化模型。【方法】利用神经突触蛋白抗体,对烟青虫成虫脑进行免疫组织化学染色标记,利用共聚焦激光扫描显微镜获得脑扫描数码图像,并结合三维图像分析软件对烟青虫脑结构进行识别分析,构建三维模型。【结果】突触蛋白抗体免疫染色将烟青虫脑和颚神经节的神经髓区域清晰标记出来。烟青虫成虫脑与颚神经节愈合而成为一体,中间具有一个孔洞,为食道穿过的通道。脑主要包括前脑、中脑和后脑3部分。依据染色标记结果识别和构建了至少16个脑神经髓结构。这些神经髓包括边界清晰的视叶、前视结节、蕈形体、中央复合体和触角叶及其亚结构。除此之外,还包括围绕这些神经髓的其他前脑神经髓区域,但这部分前脑神经髓内部边界模糊,不容易细分,而将其与颚神经节区域作为一个整体标记为中间脑,占脑总神经髓的55.05%。【结论】识别出烟青虫脑的主要功能结构区域,并成功构建了三维模型。该研究结果为进一步研究烟青虫脑接收、处理和整合感觉信息及调控行为的机制奠定了解剖学基础,并为研究烟青虫或其他昆虫脑结构发育、变异和重塑提供结构形态和体积大小依据。     

Potentialities of methoxyfenozide for the integrated management of Helicoverpa armigera (Lepidoptera: Noctuidae) on cotton in Benin,West Africa

Intensive use of chemical insecticides against Helicoverpa armigera has led to the development of resistance to the major chemical families of insecticides. Consequently, management of H. armigera using conventional chemical insecticides is increasingly difficult. Methoxyfenozide is an agonist of the insect moulting hormone 20-hydroxyecdysone that acts faster than chitin synthesis inhibitors. The present work is aimed to assess the effectiveness of methoxyfenozide for use against H. armigera on cotton in Benin, West Africa. Laboratory tests and field experiments have been carried out. For laboratory studies, topical application of methoxyfenozide was done using L2 and L5 instar larva of H. armigera. Tested methoxyfenozide concentrations varied from 24 μl/ml to 144 μl/ml and the control is water only. For field experiments, a complete randomised block design was used with methoxyfenozide (72 μl/ml) and a control (no spraying). Berthoud Ultra Low Volume sprayer was used to spray methoxyfenozide suspension at 60-l per hectare. Two sprays were applied, 7 days apart. Laboratory tests indicated that 24 h after application of methoxyfenozide, about 100% of treated L2 and L5 larva were morbid or dead compared with 0% for the control larva. There are no significant differences between tested concentrations. Morbid larvae died within 2 days. In field experiments, cotton yield harvested on methoxyfenozide treated plants was double of that obtained on untreated plants (9375 kg and 4875 kg per hectare respectively). Thus methoxyfenozide may be used as component of Integrated Pest Control Programme on cotton in Benin, West Africa.