scholarly journals Functional characterisation of Dna methylation in the pest species Helicoverpa armigera

Author(s):  
Jack W. Royle
Author(s):  
Neil W. Forrester ◽  
Matthew Cahill ◽  
Lisa J. Bird ◽  
Jacquelyn K. Layland

SummaryIn response to field pyrethroid failures against Helicoverpa armigera (Hübner) in early 1983, an insecticide resistance management (IRM) strategy was introduced for insect control in summer crops in eastern Australia. The aims of this strategy were to contain the pyrethroid resistance problem, to prevent re-selection of historical endosulfan resistance (both curative IRM) and to avoid any future problems with organophosphate/carbamate resistance (preventative IRM). An alternation strategy was adopted which was based on the rotation of unrelated chemical groups on a per generation basis, along with a strong recommendation for the use of ovicidal mixtures. These chemical countermeasures were then integrated with other non-chemical control methods (biological and cultural) into a workable integrated pest management programme. The restrictions were applied to all Helicoverpa armigera susceptible crops (including cereals, oilseeds, grain legumes, tomatoes, tobacco and cotton) and even to other co-incident pest species. From its inception, compliance with the voluntary strategy has been exceptional.


Author(s):  
Yan-Li Li ◽  
Yan-Xue Li ◽  
Xiao-Pei Wang ◽  
Xin-Le Kang ◽  
Ke-Qin Guo ◽  
...  

G protein-coupled receptors (GPCRs) are the largest family of membrane receptors in animals and humans, which transmit various signals from the extracellular environment into cells. Studies have reported that several GPCRs transmit the same signal; however, the mechanism is unclear. In the present study, we identified all 122 classical GPCRs from the genome of Helicoverpa armigera, a lepidopteran pest species. Twenty-four GPCRs were identified as upregulated at the metamorphic stage by comparing the transcriptomes of the midgut at the metamorphic and feeding stages. Nine of them were confirmed to be upregulated at the metamorphic stage. RNA interference in larvae revealed the prolactin-releasing peptide receptor (PRRPR), smoothened (SMO), adipokinetic hormone receptor (AKHR), and 5-hydroxytryptamine receptor (HTR) are involved in steroid hormone 20-hydroxyecdysone (20E)-promoted pupation. Frizzled 7 (FZD7) is involved in growth, while tachykinin-like peptides receptor 86C (TKR86C) had no effect on growth and pupation. Via these GPCRs, 20E regulated the expression of different genes, respectively, including Pten (encoding phosphatidylinositol-3,4,5-trisphosphate 3-phosphatase), FoxO (encoding forkhead box O), BrZ7 (encoding broad isoform Z7), Kr-h1 (encoding Krüppel homolog 1), Wnt (encoding Wingless/Integrated) and cMyc, with hormone receptor 3 (HHR3) as their common regulating target. PRRPR was identified as a new 20E cell membrane receptor using a binding assay. These data suggested that 20E, via different GPCRs, regulates different gene expression to integrate growth and development.


2015 ◽  
Vol 7 ◽  
pp. IJIS.S29127 ◽  
Author(s):  
Monika Mishra ◽  
Kamal Kumar Gupta ◽  
Sarita Kumar

Helicoverpa armigera HÜbner is one of the most important agricultural crop pests in the world causing heavy crop yield losses. The continued and indiscriminate use of synthetic insecticides in agriculture for their control has received wide public apprehension because of multifarious problems, including insecticide resistance, resurgence of pest species, environmental pollution, and toxic hazards to humans and nontarget organisms. These problems have necessitated the need to explore and develop alternative strategies using eco-friendly and biodegradable plant products. In view of this, the efficacy of Thevetia neriifolia methanol stem extract was evaluated against the early fourth instars of H. armigera as an antifeedant and stomach poison agent. Feeding of larvae with the diet containing 0.005%–5.0% extract resulted in 2.06%–37.35% antifeedant index; the diet with 5.0% extract caused 54.3% reduced consumption. The negative impact of extract on larval feeding resulted in 37.5%–77.7% starvation, causing adverse effects on the larval weight. Choice between control and experimental diet resulted in feeding preference of larvae for the control diet, leading to 7.3%–42.9% reduced consumption of extract-containing diet. The only exception was the diet with 0.005% extract, which could not cause any deterrence. The midgut histological architecture of H. armigera larvae fed with 0.005%–0.05% extract-containing diet with negligible antifeedant potential showed significant damage, shrinkage, and distortion and vacuolization of gut tissues and peritrophic membrane, causing the disintegration of epithelial, goblet, and regenerative cells; the damage increased with the increase in concentration. These changes in the gut caused negative impact on the digestion and absorption of food and thus nutritional deficiency in the larvae, which could probably affect their growth and development. This study reveal the appreciable stomach poison potential of T. neriifolia stem methanol extract against H. armigera larvae, which can be explored as an eco-friendly pest control strategy.


1999 ◽  
Vol 89 (3) ◽  
pp. 201-207 ◽  
Author(s):  
J.P. Cunningham ◽  
M.P. Zalucki ◽  
S.A. West

AbstractRecent experimental evidence has shown that learning occurs in the host selection behaviour of Helicoverpa armigera (Hübner), one of the world‘s most important agricultural pests. This paper discusses how the occurrence of learning changes our understanding of the host selection behaviour of this polyphagous moth. Host preferences determined from previous laboratory studies may be vastly different from preferences exhibited by moths in the field, where the abundance of particular hosts may be more likely to determine host preference. In support of this prediction, a number of field studies have shown that the ‘attractiveness’ of different hosts for H. armigera oviposition may depend on the relative abundance of these host species. Insect learning may play a fundamental role in the design and application of present and future integrated pest management strategies such as the use of host volatiles, trap crops and resistant crop varieties for monitoring and controlling this important pest species.


2019 ◽  
Author(s):  
Wendy A. Valencia-Montoya ◽  
Samia Elfekih ◽  
Henry L. North ◽  
Joana I. Meier ◽  
Ian A. Warren ◽  
...  

AbstractHybridization between invasive and native species has raised global concern given the dramatic increase in species range shifts and pest outbreaks due to climate change, development of suitable agroecosystems, and anthropogenic dispersal. Nevertheless, secondary contact between sister lineages of local and invasive species provides a natural laboratory to understand the factors that determine introgression and the maintenance or loss of species barriers. Here, we characterize the early evolutionary outcomes following secondary contact between invasive Helicoverpa armigera and H. zea in Brazil. We carried out whole-genome resequencing of Helicoverpa moths from Brazil in two temporal samples: during the outbreak of H. armigera in 2013, and more recent populations from 2017. There is evidence for a burst of hybridization and widespread introgression from local H. zea into invasive H. armigera coinciding with H. armigera expansion in 2013. However, in H. armigera, admixture proportions were reduced between 2013 and 2017, indicating a decline in hybridization rates. Recent populations also showed shorter introgressed tracks suggesting selection against admixture. In contrast to the genome-wide pattern, there was striking evidence for introgression of a single region including an insecticide-resistance allele from the invasive H. armigera into local H. zea, which increased in frequency over time but was localized within the genome. In summary, despite extensive gene-flow after secondary contact, the species boundaries are largely maintained except for the single introgressed region containing the insecticide-resistant locus. We document the worst-case scenario for an invasive species, in which there are now two pest species instead of one, and the native species has acquired resistance to pyrethroid insecticides through introgression and hybridization, with significant implications for pest management in future population expansions and introductions of novel resistance genes from new invasive H. armigera populations.Author summarySecondary contact occurs when related species with non-overlapping ranges are geographically reunited. Scenarios of secondary contact have increased due to anthropogenic movement of species outside of their native range, often resulting in invasive species that successfully spread and stabilised in the new environment. This is the case for Helicoverpa armigera, a major agricultural pest in the Old World that has recently invaded the Americas, where it reunited with its closest relative, H. zea. While some authors reported hybridisation, and hypothesised about the potential emergence of novel ecotypes and the exchange of pesticide-resistant genes, these outcomes have not been tested yet. We examine these outcomes by sequencing individuals from both species in Brazil, collected in 2013 after outbreaks of H. armigera were reported, and individuals collected during 2017. We discovered that despite hybridisation, these moths have not collapsed into a single species nor formed new ecotypes, and that the species distinctiveness is maintained through selection against most of the foreign genotypes that cross species boundaries. However, we found that hybridisation mediated the rapid acquisition of a H. armigera gene conferring resistance to pyrethroids by H. zea. The overall decline in populations of both species during the interval covered by this study means that our results are likely to reflect the consequences of hybridization events early after invasion, despite the likely ongoing introduction of H. armigera genetic diversity through trade across the South American continent. Our results provide a rare example of adaptive transferral of variation right after invasion and elucidate the dynamics of insecticide resistance evolution in H. zea.


Author(s):  
Snehel Chakravarty ◽  
C.P. Srivastava ◽  
Ram Keval

Background: Helicoverpa armigera (Hübner) is an important biotic constraint to major grain legumes in India. Biological characterization of any pest species is critical for making effective management decisions. Thus, this study comprehensively presents the biological and reproductive demographic traits of different geographic populations of H. armigera across the country. Methods: In this field-laboratory investigation (2015-18), populations from 20 localities were evaluated for developmental period of all the life stages, survival and reproduction and growth and fitness indices. All these parameters were recorded from the maintained insect cultures of each location from second filial (F2) generation.Result: The mean developmental periods of the immature stages, as well as adult longevity, were found to be longest in the Cooch Behar population. In contrast, the populations from South Zone took significantly shorter duration over others to complete their life cycle. All the populations were found to be female-biased, but significant differences were observed for reproductive competence of female moths. Wide variations were also observed in the relative growth and fitness indices, with the highest recorded from Varanasi population. Cluster analysis differentiated studied populations into two distinct groups. Such variations seem to be due to probable genetic heterogeneity in H. armigera populations of India.


2020 ◽  
Vol 37 (9) ◽  
pp. 2568-2583 ◽  
Author(s):  
Wendy A Valencia-Montoya ◽  
Samia Elfekih ◽  
Henry L North ◽  
Joana I Meier ◽  
Ian A Warren ◽  
...  

Abstract Hybridization between invasive and native species has raised global concern, given the dramatic increase in species range shifts and pest outbreaks due to anthropogenic dispersal. Nevertheless, secondary contact between sister lineages of local and invasive species provides a natural laboratory to understand the factors that determine introgression and the maintenance or loss of species barriers. Here, we characterize the early evolutionary outcomes following secondary contact between invasive Helicoverpa armigera and native H. zea in Brazil. We carried out whole-genome resequencing of Helicoverpa moths from Brazil in two temporal samples: during the outbreak of H. armigera in 2013 and 2017. There is evidence for a burst of hybridization and widespread introgression from local H. zea into invasive H. armigera coinciding with H. armigera expansion in 2013. However, in H. armigera, the admixture proportion and the length of introgressed blocks were significantly reduced between 2013 and 2017, suggesting selection against admixture. In contrast to the genome-wide pattern, there was striking evidence for adaptive introgression of a single region from the invasive H. armigera into local H. zea, including an insecticide resistance allele that increased in frequency over time. In summary, despite extensive gene flow after secondary contact, the species boundaries are largely maintained except for the single introgressed region containing the insecticide-resistant locus. We document the worst-case scenario for an invasive species, in which there are now two pest species instead of one, and the native species has acquired resistance to pyrethroid insecticides through introgression.


Genome ◽  
1989 ◽  
Vol 32 (6) ◽  
pp. 967-971 ◽  
Author(s):  
Jennifer H. Fisk

The economically important pest species Helicoverpa armigera and H. punctigera have a karyotype consisting of 31 pairs of chromosomes. The chromosomes are in a graded series of sizes such that pairs cannot be differentiated. Cytological evidence suggests that female meiosis is achiasmatic. Precocious separation of bivalents into univalents at metaphase I was observed in some spermatocytes of H. punctigera. This species also had a consistently greater number of bivalents with fully terminalised chiasmata in each spermatocyte at male metaphase I than H. armigera.Key words: Lepidoptera, Helicoverpa, achiasmatic meiosis, karyotype.


2019 ◽  
Vol 19 (5) ◽  
Author(s):  
Peng Wang ◽  
Michael J Furlong ◽  
Thomas K Walsh ◽  
Myron P Zalucki

Abstract Insect herbivores can modify their foraging behavior to obtain a balanced food intake, and they tend to move between food sources with different nutrient values. We investigated this movement in early instar larvae of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) using a putative optimal artificial diet (OP) and high protein (HP) and high carbohydrate (HC) artificial diets based on protein (p) and carbohydrate (c) ratios. Larvae were allowed to choose between the same kind of diet cubes (effectively no-choice), or diet cubes with different p: c ratios. In no-choice tests, we found that first instar larvae remained longest on OP diet and spent the least time on HC diet, while third instar larvae remained longest on HC diet and spent least time on OP diet. First instar larvae moved the most when provided with HC diet, while third instar larvae moved most when provided with OP diet. However, both stages moved the least when allowed to choose between diet cubes with different p: c ratios. The relative growth rate decreased when larvae increased their movement, but this influence was not evident when larvae fed on HC diet. Larvae that fed only on HC diet had the highest relative growth rate, followed by larvae with access to all diets simultaneously, indicating a behavior to mix nutrient intake. We relate these findings to behavior of this major pest species under field conditions.


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