Sustainable control of cotton bollworm in small-scale cotton-production systems

Insecticides currently account for around 45% of cotton-growing costs for over 30 million small-scale producers in Asia at a cost of US$811 million each year. In order to reduce the financial and environmental impact of cotton insecticide use, this project built on recent work in India to advance farmers’ ability to use insecticides appropriately for control of cotton bollworm in India, Pakistan and China. The project has provided detailed, practical recommendations to empower farmers to adopt insect resistance management, and has developed easy-to-use insecticide quality and resistance detection kits. Direct impact from the village programme in 2004/05 is a net benefit to participating farmers of US$11 million. This project provides UK input into a much larger (US$4 million) CFC projec

Changing trends in cotton pest management

The cotton crop sustains more insects than any other crop grown commercially world-wide. Any single insecticidal intervention to control a particular pest invariably sets up a chain reaction causing short-term imbalances in the ecosystem, mostly in favour of the pest in the long run. Thus over the years, insecticide use was establishing undesirable ecological and economic consequences for cotton cultivators and administrators in many countries. Individual insecticide molecules when first introduced have always been impressive in their rapid efficacy in controlling target insect pests. As long the target pests are effectively controlled with the pesticide, cultivators do not care for the naturally occurring predators and parasites in their ecosystems. Unfortunately almost all the insecticides have inadvertent adverse effects on naturally occurring beneficial insects. However, phytophagous target pests usually develop resistance much faster than entomophages, thereby causing pest populations to survive the pesticide, increase in numbers in the absence of natural control, and so generate outbreaks. The cotton crop has been subjected to more pesticide exposure than any other crop, in all cotton growing countries of the world. Intense insecticide use has resulted in insect resistance to insecticides, pesticide residues, and the resurgence of minor pests causing immense problems to cultivators. With the most reliable tools turning redundant, pest management experts started exploring the utility of naturally occurring pest control components as alternatives to replace the chemical insecticides. Thus, Integrated Pest Management (IPM) programs began to take shape as ‘intelligent selection and use of pest management tactics which results in favorable ecological, sociological and environmental consequences’ as defined by Rabb (1972). Insecticide Resistance Management (IRM) strategies have strengthened pest management systems by identifying appropriate insecticides, rates and timings so as to delay resistance, ensure effective control of target pests, and conserve naturally occurring biological control for enhanced sustainability of ecosystems. With the recent introduction of Bt-cotton, novel eco-friendly pesticides and IRM strategies, coupled with the trends in technology dissemination through area-wide farmer participatory approaches and farmer field schools, IPM programs all over the world have improved their sustainability and economic success

Mitochondrial DNA analysis of field populations of Helicoverpa armigera (Lepidoptera: Noctuidae) and of its relationship to H. zea

Background: Helicoverpa armigera and H. zea are amongst the most significant polyphagous pest lepidopteran species in the Old and New Worlds respectively. Separation of H. armigera and H. zea is difficult and is usually only achieved through morphological differences in the genitalia. They are capable of interbreeding to produce fertile offspring. The single species status of H. armigera has been doubted, due to its wide distribution and plant host range across the Old World. This study explores the global genetic diversity of H. armigera and its evolutionary relationship to H zea. Results: We obtained partial (511 bp) mitochondrial DNA (mtDNA) Cytochrome Oxidase-I(COI) sequences for 249 individuals of H. armigera sampled from Australia, Burkina Faso, Uganda, China, India and Pakistan which were associated with various host plants. Single nucleotide polymorphisms (SNPs) within the partial COI gene differentiated H. armigera populations into 33 mtDNA haplotypes. Shared haplotypes between continents, low F-statistic values and low nucleotide diversity between countries (0.0017 – 0.0038) suggests high mobility in this pest. Phylogenetic analysis of four major Helicoverpa pest species indicates that H. punctigera is basal to H. assulta, which is in turn basal to H. armigera and H. zea. Samples from North and South America suggest that H. zea is also a single species across its distribution. Our data reveal short genetic distances between H. armigera and H. zea which seem to have been established via a founder event from H. armigera stock at around 1.5 million years ago.Conclusion: Our mitochondrial DNA sequence data supports the single species status of H. armigera across Africa, Asia and Australia. The evidence for inter-continental gene flow observed in this study is consistent with published evidence of the capacity of this species to migrate over long distances. The finding of high genetic similarity between Old World H. armigera and New World H. zea emphasises the need to consider work on both pests when building pest management strategies for either

Haplotype network based on partial mtDNA COI (511 bp) of , sampled from Australia, Burkina Faso, Uganda, China, India and Pakistan

<p><b>Copyright information:</b></p><p>Taken from "Mitochondrial DNA analysis of field populations of (Lepidoptera: Noctuidae) and of its relationship to "</p><p>http://www.biomedcentral.com/1471-2148/7/117</p><p>BMC Evolutionary Biology 2007;7():117-117.</p><p>Published online 14 Jul 2007</p><p>PMCID:PMC1934911.</p><p></p> Each haplotype is represented by a circle, and is identified by a number 1–33. Haplotype 1 included 156 individuals; haplotypes 2, 3, 5 and 10 have 17, 15, 5 and 10 individuals respectively. Haplotypes 6, 32 and 33 each have 4 individuals. Haplotypes 13 and 17 each has 3 individuals, and Haplotype 4, 11, 14, 15 and 19 each have 2 individuals. All remaining haplotypes have 1 individual each. Each base change involved in the differentiation between haplotypes is represented by a solid circle

Maximum Likelihood (ML) tree of (Harm-1 to Harm-31), (Hzea-1, Hzea-2), and based on partial COI haplotypes sequences

<p><b>Copyright information:</b></p><p>Taken from "Mitochondrial DNA analysis of field populations of (Lepidoptera: Noctuidae) and of its relationship to "</p><p>http://www.biomedcentral.com/1471-2148/7/117</p><p>BMC Evolutionary Biology 2007;7():117-117.</p><p>Published online 14 Jul 2007</p><p>PMCID:PMC1934911.</p><p></p> Numbers above the nodes indicate bootstrap support. The outgroup used was . The inclusion of additional haplotypes Harm-32, Harm-33, and Hzea-3 to Hzea-11 did not alter the overall topology, and bootstrap values of the ML tree after 1,000 bootstrap replications remained high, with all haplotypes confidently clustered (bootstrap value = 96) within the clade. remained basal to (bootstrap value = 99), and the /clade (bootstrap value = 78) shared a most common ancestor with (bootstrap value = 97) (data not shown)