Return migration of Helicoverpa armigera (Lepidoptera: Noctuidae) during autumn in northern China

The autumn migration of Helicoverpa armigera (Hübner) was observed with radar and two types of light-trap at Langfang, Hebei province, China in 2001 and 2002. The sudden increase in the proportion of H. armigera moths in the searchlight trap indicated migration into the area and catches increased 10-fold during the second half of the night due to the landing of migrants before dawn. The moths' migratory flights took place at up to 2000 m above the ground, and moths flew differentially at times, and heights, when favourable (i.e. northerly) winds occurred. This facilitated the maximum displacement of moths towards the south during these 'return' migrations. The moths flew over the radar site at consistently high densities through the night, and the resulting flight durations of c. 10 h, at displacement speeds of 30-33 km h-1, would allow moths emerging in the far northeast of China (i.e. Liaoning and Jilin provinces and the Inner Mongolia autonomous region) to migrate into northern China (Hebei, Shandong and Henan provinces). The association of the seasonal migratory movements of H. armigera with crops in northern China is briefly discussed.     

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.     

Overwintering survival and spring emergence of Helicoverpa armigera (Lepidoptera: Noctuidae) in northern Greece

Overwintering survival of Helicoverpa armigera (Hübner) was studied under field conditions during the winter of 2004-2005 and 2005-2006 to clarify whether a local population of this insect is established in northern Greece. Additionally, the postdiapause eclosion times of the overwintering generation was compared with adult male dynamics using pheromone traps. Our study supplies strong evidence that part, if not all, of the late-season generation of H. armigera overwinters as diapausing pupa in northern Greece, suggesting that a local population exists in this area. Pupae enter diapause during September and October in response to declining temperatures and photoperiod. A limited number of degree-days in autumn prevented part of the population from developing to the diapausing pupal stage. Larvae of H. armigera that were placed in field conditions late in October were not able to pupate and died. The termination of diapause and the eclosion of adults in the following spring were determined by the local soil temperatures. Diapause terminated between mid-April and early May, and adult emergence occurred within a 4- to 6-wk period from late April to early June. Females emerged slightly earlier than the males. The emergence of 10, 25, 50, 75, and 90% of adults required 153, 199, 252, 303, and 347 DD, respectively. Differences in timing and degree of overlap between adult emergence from the experimental population and pheromone trap catches suggests that the spring population of this species also includes immigrants.     

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.     

Radar observations of the autumn migration of the beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) and other moths in northern China

The autumn return migration of the beet armyworm Spodoptera exigua Hübner and other insects in northern China was observed with radar and with a simultaneously-operated searchlight trap and ground light-trap at a site in Langfang, near Beijing. The searchlight trap was found to be an efficient tool for trapping migrants and, operated alongside a ground light-trap, could distinguish migrant from locally-flying species. It was confirmed that S. exigua and some other species were high-altitude nocturnal windborne migrants during September and October in northern China. Maximum density of moths typically occurred below 500 m, and strong layering was often observed at about 200 m above ground level in airflows that would carry the moths towards the south. Descent of S. exigua in the vicinity of the radar site in late September was often associated with rain.     

Mitochondrial genome of the cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) and comparison with other Lepidopterans

We present the complete sequence of the mitochondrial genome (mitogenome) of the cotton bollworm Helicoverpa armigera. The 15,347-bp mitogenome of H. armigera was arranged in the same order described for all other sequenced lepidopterans, which differs from the most common type found in insects, due to the movement of trnM to a position 5'-upstream of trnI. The gene overlap in the H. armigera mitogenome is totally 23 bp in six locations. The H. armigera mitogenome has a total of 175 bp of intergenic spacer sequences spread over 14 regions ranging in size from 1 to 45 bp. The nucleotide composition of the whole mitogenome of H. armigera is highly A+T biased, accounting for 80.97%, with a slightly positive AT skewness and negative GC skewness, indicating the occurrence of more A than T, C more than G. The protein-encoding genes have typical mitochondrial start codons, except for cox1, which contains the unusual CGA. The cox1, cox2, and nad4 genes have incomplete stop codons (T). The lrRNA and srRNA genes are 1395 and 794-bp long, respectively. All tRNAs have a typical cloverleaf structure of mitochondrial tRNAs, except for trnS1(AGN), the dihydrouridine arm of which could not form a stable stem-loop structure. The H. armigera A+T-rich region contains a conserved structure combining the motif ATAGA and a 19-bp poly-T stretch, but absence of the 9-bp poly-A element upstream of trnM.     

Exon-primed intron-crossing (EPIC) PCR markers of Helicoverpa armigera (Lepidoptera: Noctuidae)

Applying microsatellite DNA markers in population genetic studies of the pest moth Helicoverpa armigera is subject to numerous technical problems, such as the high frequency of null alleles, occurrence of size homoplasy, presence of multiple copies of flanking sequence in the genome and the lack of PCR amplification robustness between populations. To overcome these difficulties, we developed exon-primed intron-crossing (EPIC) nuclear DNA markers for H. armigera based on ribosomal protein (Rp) and the Dopa Decarboxylase (DDC) genes and sequenced alleles showing length polymorphisms. Allele length polymorphisms were usually from random indels (insertions or deletions) within introns, although variation of short dinucleotide DNA repeat units was also detected. Mapping crosses demonstrated Mendelian inheritance patterns for these EPIC markers and the absence of both null alleles and allele 'dropouts'. Three examples of allele size homoplasies due to indels were detected in EPIC markers RpL3, RpS6 and DDC, while sequencing of multiple individuals across 11 randomly selected alleles did not detect indel size homoplasies. The robustness of the EPIC-PCR markers was demonstrated by PCR amplification in the related species, H. zea, H. assulta and H. punctigera.     

Evaluation of Helicoverpa armigera Nucleopolyhedrovirus (HearNPV) for Control of Helicoverpa armigera (Lepidoptera: Noctuidae) on Citrus in South Africa

A concentration of 1.15×10⁷ OBs/mL of HearNPV, sprayed using a knapsack, resulted in a 100% reduction in Helicoverpa armigera larval infestation within 7 days on tomato plants in a hot house environment. A 10-fold lower concentration, 1.15×10⁶ OBs/mL, resulted in a 100% reduction within 16 days. These two concentrations reduced damage to tomatoes by 81 and 69%, respectively. In two field trials on navel oranges, the lower concentration and an additional even lower concentration of 7.26×10⁵ OBs/mL, both resulted in a 100% reduction in H. armigera infestation within 14 days or longer. H. armigera damage to fruit was reduced by up to 84 and 75%, respectively, in the two trials. Rejection for export was reduced by 96 and 62%. This could imply a saving of US$339 per hectare compared to the untreated control. These results were better than those achieved with Bacillus thuringiensis and various standard chemical insecticides used in the same trials. Reasons for these results are discussed.     

Resistance monitoring of Helicoverpa armigera (Lepidoptera Noctuidae) to Bacillus thuringiensis insecticidal protein in China

Sensitivities of Helicoverpa armigera (Hübner) field populations to Bacillus thuringiensis (Bt) insecticidal protein CrylAc were monitored during 1998-2000 in China. A total of 41 strains was sampled, and most of them were collected from Bt cotton planting regions. The range of IC50 values (concentration producing 50% inhibition of larval development to third instar) among different populations in 1998,1999, and 2000 were 0.020-0.105 microg/ml, 0.016-0.099 microg/ml, and 0.016-0.080 microg/ml, respectively. Diagnostic concentration studies (IC99) showed that the percentage of individuals reaching third instar ranged from 0 to 4.35%, with only eight of the 41 tested populations showing values above 0%. Also interesting was a trend over successive years in which fewer populations contained individuals that survived the diagnostic concentration by reaching third instar. Considering these data, it was determined that the field populations sampled during the 3-yr study were susceptible to CrylAc protein, and that movement toward resistance among H. armigera populations was not apparent.     

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。     

A true summer diapause induced by high temperatures in the cotton bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae)

Summer diapause in the cotton bollworm, Helicoverpa armigera (Hübner), which prolongs the pupal stage, particularly in males, is induced by high temperatures. In the laboratory, summer-diapausing pupae of H. armigera were induced at high temperatures (33-39 degrees C) with a photoperiod of LD8:16; winter-diapausing and non-diapausing pupae, cultured at 20 degrees C with a photoperiod of LD8:16 and at 27 degrees C, LD16:8, respectively, acted as a control. Retention time of eye spots, weight, and lipid and glycogen levels were compared. At high temperatures, both body weight and energy storage capacity were much higher in summer-diapausing pupae than in non-diapausing pupae reared at 33-39 degrees C. At temperatures (>33 degrees C) high enough to maintain summer diapause, the eye spots of summer-diapausing pupae did not move during the 30-day experiment. However, eye spots of summer-diapausing pupae placed at 30 degrees C began to move about 10 days after they were transferred, significantly later than in non-diapausing pupae reared at 33-39 degrees C or non-diapausing pupae reared at 27 degrees C, which initiated eye spot movement 2 days after pupation. The differences in retention time of eye spots between summer- and winter-diapausing pupae shows that winter diapause is more intense than summer diapause in this insect. The weight loss, and lipid and glycogen metabolism curves indicate that the summer-diapausing pupae's metabolism is very low. We conclude that summer diapause in the cotton bollworm is a true diapause and that the summer diapause enables the cotton bollworm to withstand the high temperatures of summer.     

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.     

Interaction of HaNPVs with two novel insecticides against Helicoverpa armigera Hubner (Noctuidae: Lepidoptera)

Nucleopolyhedrosis viruses can be utilized for effective management of agriculture pests. Their efficacy can be increased if they are mixed with certain insecticides. In the current study, HaNPV was mixed with two insecticides: spinetoram and emamectin benzoate in various combinations and applied to larvae of H. armigera in laboratory conditions. There were a total of 15 combinations of HaNPV with each of the two insecticides in addition to five doses of HaNPV and three doses of insecticides alone. The synergistic and antagonistic effects of combinations were explored. The results revealed that there was synergistic effect of HaNPV @ 0.5 × 10⁹ PIB/ml × Spinetoram @ 40, 20, 10 ml/100 L of water. In case of emamectin benzoate, synergistic effects were recorded at 1 × 10⁹ PIB/ml HaNPV × emamectin benzoate @ 100 ml/100 L of water. However, 0.5 × 10⁹ PIB/ml HaNPV has synergistic effects with all three doses of emamectin benzoate. The results suggested that HaNPV can be used in combination with spinetoram and emamectin benzoate for the management of resistant population of H. armigera.     

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.     

Elevated CO2 may alter pheromonal communication in Helicoverpa armigera (Lepidoptera: Noctuidae)

Carbon dioxide (CO₂) as a greenhouse gas has been increasing in recent decades. Because an elevated atmospheric CO₂ influences insect physiology and behaviour, we hypothesize that pheromone–mediated communication in the moth is affected by an increased CO₂ level. We test the behavioural responses of male Helicoverpa armigera to sex pheromone in a wind tunnel, demonstrating a significant reduction of approaching behaviour to the odour source at a high CO₂ level (1000 ppm). Electroantennogram (EAG) responses of male to the pheromone component are also significantly suppressed in high CO₂ environments (600 and 1000 ppm), indicating that a high CO₂ level inhibits both behavioural and electrophysiological responses of male to the sex pheromone. Interestingly, the EAG response of the whole head preparation of males is influenced more by the elevated CO₂ level than that of the antenna‐cut preparation. A sequential increase of CO₂ levels from an ambient CO₂ level also decreases the EAG response of the whole head but not of the labial palp‐removed head, implying a potential mediation of labial palp in the head where the CO₂ receptor is located. By contrast, sex pheromone production in females reared under or shifted to an elevated CO₂ condition is increased, and the putative underlying mechanism for this is discussed. The present study provides an insight into the adaptive strategy of moth pheromone communication in a changing environment.     

基于支持向量回归的棉铃虫蛹发育历期估测

温度与发育速率关系模拟是昆虫学研究的一个重要内容, 传统基于经验风险最小的非线性参数模型(Logan模型、Lactin模型和王氏模型)存在诸多弊端。本文基于结构风险最小的改进支持向量回归（SVR）研究温度与棉铃虫Helicoverpa armigera蛹发育历期关系。结果表明: 与传统非线性模型相比, SVR模型性能优异; 基于全部92个样本, SVR模型拟合和留一法预测的决定系数R²分别为0.998和0.996, 估测的蛹期三基点温度更可信。从全部样本中依温度均匀选取部分样本实施独立预测, 当训练集为20个样本时, SVR模型独立预测的R²为0.981, 优于传统非线性模型中独立预测最佳的Lactin模型（R²=0.958）; 当训练集进一步减少到12个样本时, SVR模型的R²仅降低到0.964, 而传统非线性模型均已不适用。结果提示SVR模型在小样本情况下较传统非线性模型优势明显, 在昆虫发育历期估测建模中有应用前景。     

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.     

In-season changes in resistance to insecticides in Helicoverpa armigera (Lepidoptera: Noctuidae) in India

Discriminating doses of fenvalerate, cypermethrin, quinalphos, and endosulfan were determined with an insecticide-susceptible Helicoverpa armigera (Hübner) strain. In-season changes in insecticide resistance were monitored with discriminating dose assays at weekly intervals throughout the cropping season for 6 yr from 1993 to 1999 in central India. Resistance to pyrethroids was high throughout all seasons. Resistance to 0.75 microg of quinalphos was consistent, with seasonal averages ranging from 23 to 27% survival over the 6 yr. Resistance to 10.0 microg of endosulfan was moderately high at an average of 40-47% survival during 1993-1994 and in 1997-1998. It was lower in 1996-1997 at 27%, and in 1998-1999 at 33%. The weekly monitoring data for all seasons were pooled and the consolidated 6-yr seasonal average profile indicated that resistance to quinalphos and endosulfan was low during September at 21 and 27% survival, respectively, but increased to 28 and 37% by the end of November. Resistance levels to organophosphates and endosulfan increased during the season, depending on the use of these compounds. At almost all monitoring sites, the within-season changes in quinalphos resistance for all seasons through the study period followed a trend similar to that of endosulfan. The results suggest the possibility of cross-resistance between these compounds. Based on this study and the existing information on cotton pest management, we have developed a "window strategy" for cotton pest management with specific emphasis on the management of insecticides for effective control of H. armigera. This strategy has contributed to improved control at reduced costs in extensive trials.