Project description:Sugarcane stalk borer larvae were grown on artificial diet and maintained at 25°C and 60±10% relative humidity with a 14 h/10 h light/dark cycle. Second instar larvae were maintained under fasting conditions for 18 h and transferred to two-month old plants (genotype SP80-3280, CTC, Brazil). Leaves were collected after 30 min and 24 h of exposure to herbivory for the control and experimental groups. Two plantlets were used for each time point. Extraction of total RNA was performed separately on each sample pool. Keywords: time course of stress response
Project description:Diatraea saccharalis (Fabricius, 1794) (Lepidoptera: Crambidae), the sugarcane borer, spends most of its life cycle inside the galleries it burrows into sugarcane stalk, where two rot-causing fungi Colletotrichum falcatum (Went, 1893) and Fusarium verticillioides (Nirenberg, 1976) are commonly found. Results have shown that microbiota harbored by D. saccharalis inhibits the growth of F. verticillioides and C. falcatum. D. saccharalis larvae were collected from chemical-free field plants, and yeast and bacteria from third and fourth-instar D. saccharalis regurgitate were isolated onto appropriate media. The percentage of F. verticillioides and C. falcatum mycelial growth inhibition was recorded. Out of 32 yeast isolates, 9 exerted 30 to 40% growth inhibition of C. falcatum or F. verticillioides. When 24 bacterial isolates were confronted with rot-causing fungi, six inhibited C. falcatum growth by 30 to 60%, and 24 isolates inhibited 30 to 60% of F. verticillioides growth. Bacteria and yeast isolates were identified through DNA sequencing of part of 16S rDNA and part of ITS1-5.8S-ITS2, respectively, revealing an abundance of isolates with sequence similarity to Klebsiella and Bacillus and Meyerozyma, which have been used as biological control agents and their ability to promote plant growth has been demonstrated. We have shown that microorganisms from borer regurgitate inhibit phytopathogen growth in vitro. Still, further investigation of the possible functions of D. saccharalis-associated microorganisms may help understand their ecological role in plant-insect-phytopathogen interaction.
Project description:The sugarcane borer (Diatraea saccharalis, Fabricius, 1794) is a devastating pest that causes millions of dollars of losses each year to sugarcane producers by reducing sugar and ethanol yields. The control of this pest is difficult due to its endophytic behavior and rapid development. Pest management through biotechnological approaches has emerged in recent years as an alternative to currently applied methods. Genetic information about the target pests is often required to perform biotechnology-based management. The genomic and transcriptomic data for D. saccharalis are very limited. Herein, we report a tissue-specific transcriptome of D. saccharalis larvae and a differential expression analysis highlighting the physiological characteristics of this pest in response to two different diets: sugarcane and an artificial diet. Sequencing was performed on the Illumina HiSeq 2000 platform, and a de novo assembly was generated. A total of 27,626 protein-coding unigenes were identified, among which 1,934 sequences were differentially expressed between treatments. Processes such as defence, digestion, detoxification, signaling, and transport were highly represented among the differentially expressed genes (DEGs). Furthermore, seven aminopeptidase genes were identified as candidates to encode receptors of Cry proteins, which are toxins of Bacillus thuringiensis used to control lepidopteran pests. Since plant-insect interactions have produced a considerable number of adaptive responses in hosts and herbivorous insects, the success of phytophagous insects relies on their ability to overcome challenges such as the response to plant defences and the intake of nutrients. In this study, we identified metabolic pathways and specific genes involved in these processes. Thus, our data strongly contribute to the knowledge advancement of insect transcripts, which can be a source of target genes for pest management.
Project description:The sugarcane borer moth, Diatraea saccharalis, is one of the most important pests of sugarcane and maize crops in the Western Hemisphere. The pest is widespread throughout South and Central America, the Caribbean region and the southern United States. One of the most intriguing features of D. saccharalis population dynamics is the high rate of range expansion reported in recent years. To shed light on the history of colonization of D. saccharalis, we investigated the genetic structure and diversity in American populations using single nucleotide polymorphism (SNPs) markers throughout the genome and sequences of the mitochondrial gene cytochrome oxidase (COI). Our primary goal was to propose possible dispersal routes from the putative center of origin that can explain the spatial pattern of genetic diversity. Our findings showed a clear correspondence between genetic structure and the geographical distributions of this pest insect on the American continents. The clustering analyses indicated three distinct groups: one composed of Brazilian populations, a second group composed of populations from El Salvador, Mexico, Texas and Louisiana and a third group composed of the Florida population. The predicted time of divergence predates the agriculture expansion period, but the pattern of distribution of haplotype diversity suggests that human-mediated movement was most likely the factor responsible for the widespread distribution in the Americas. The study of the early history of D. saccharalis promotes a better understanding of range expansion, the history of invasion, and demographic patterns of pest populations in the Americas.
Project description:The sugarcane borer or corn stalk borer, Diatraea Guilding is polyphagous insect pest of many important crops such as corn, sorghum and sugarcane. Losses arising from the attack of Diatraea species have been a serious problem, which may cause loss in sugarcane production around 0.25% in sugar, 0.20% in alcohol and 0.77% of body weight for every 1% infestation and up to 21% in corn production fields. In Brazil, the most commonly reported species are Diatraea saccharalis (Fabricius, 1794) and Diatraea impersonatella (Walker, 1863) (= D. flavipennella). However, multiple other species of Diatraea have been identified in Brazil according to the literature. Currently, little information exists on the presence of the other species causing injury to sugarcane and corn. The objectives of this study were to improve the accuracy of species assignment, evaluate the population genetic structure, and address many of the outstanding questions of systematics and evolution of Brazilian populations of D. saccharalis. To address these main questions, classical taxonomic methods were used, focused on morphological characterization of the reproductive organs, especially the male genitalia. In addition, genetic studies were performed using simple sequence repeats (SSR) and a fragment of cytochrome C oxidase subunit I (COI) gene. The data and findings from this research will contribute to the understanding of evolutionary aspects of insect pests in order to develop more effective and sustainable population management practices.
Project description:We provide insights into how the interactions of two entomopathogenic fungi and a virus play a role in virulence, disease development, and pathogen reproduction for an economically important insect crop pest, the sugarcane borer Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae). In our model system, we highlight the antagonistic effects of the co-inoculation of Beauveria bassiana and granulovirus (DisaGV) on virulence, compared to their single counterparts. By contrast, combinations of Metarhizium anisopliae and B. bassiana, or M. anisopliae and DisaGV, have resulted in additive effects against the insect. Intriguingly, most cadavers that were derived from dual or triple infections, produced signs/symptoms of only one species after the death of the infected host. In the combination of fungi and DisaGV, there was a trend where a higher proportion of viral infection bearing conspicuous symptoms occurred, except when the larvae were inoculated with M. anisopliae and DisaGV at the two highest inoculum rates. Co-infections with B. bassiana and M. anisopliae did not affect pathogen reproduction, since the sporulation from co-inoculated larvae did not differ from their single counterparts.