ABSTRACT
Actinomycetes constitute a large group of Gram-positive bacteria present in different habitats. One of these habitats involves the association of these bacteria with insects. In this work, we have studied twenty-four actinomycetes strains isolated from the intestinal tract and feces from larvae of the xylophagous coleopteran Cerambyx welensii and have shown that seventeen strains present hydrolytic activity of some of the following substrates: cellulose, hemicellulose, starch and proteins. Fourteen of the isolates produce antimicrobial molecules against the Gram-positive bacteria Micrococcus luteus. Analysis of seven strains led us to identify the production of a wide number of compounds including streptanoate, alpiniamide A, alteramides A and B, coproporphyrin III, deferoxamine, demethylenenocardamine, dihydropicromycin, nocardamine, picromycin, surugamides A, B, C, D and E, tirandamycins A and B, and valinomycin. A significant number of other compounds, whose molecular formulae are not included in the Dictionary of Natural Products (DNP), were also present in the extracts analyzed, which opens up the possibility of identifying new active antibiotics. Molecular identification of ten of the isolated bacteria determined that six of them belong to the genus Streptomyces, two of them are included in the genus Amycolatopsis and two in the genus Nocardiopsis.
ABSTRACT
BACKGROUND: Geographic variation in male response to sex pheromone lures has been studied in the field in a number of moth species. However, only a few studies have investigated geographic variation in female calling and sex pheromone under field conditions. For an effective field implementation of sex pheromone lures, it is essential to know the local sex pheromone blend and local timing of sexual communication. We investigated the level and extent of geographic variation in the sexual communication of the important agricultural pest Helicoverpa armigera (Lepidoptera, Noctuidae) in three continents. RESULTS: We found there is no genetic variation in the calling behavior of H. armigera. In the female sex pheromone, we found more between-population variation than within-population variation. In male response experiments, we found geographic variation as well. Strikingly, when adding the antagonistic compound Z11-16:OAc to the pheromone blend of H. armigera, significantly fewer males were caught in Australia and China, but not in Spain. This variation is likely not only due to local environmental conditions, such as photoperiod and temperature, but also to the presence of other closely related species with which communication interference may occur. CONCLUSION: Finding geographic variation in both the female sexual signal and the male response in this pest calls for region-specific pheromone lures. Our study shows that the analysis of geographic variation in moth female sex pheromones as well as male responses is important for effectively monitoring pest species that occur around the globe. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Subject(s)
Moths , Animals , Australia , China , Female , Male , Sex Attractants/pharmacology , SpainABSTRACT
We analysed electroantennogram (EAG) responses of male and female adults of the European grapevine moth Lobesiabotrana (Denis et Schiffermüller) (Lepidoptera: Tortricidae) collected as larvae from grapevine (Vitis vinifera L.) and flax-leaved daphne (Daphne gnidium L.). The host-plant odorants tested were either V. vinifera-specific [1-octen-3-ol, (E)-ß-farnesene, (E)-4,8-dimethyl-1,3,7-nonatriene], D. gnidium-specific (2-ethyl-hexan-1-ol, benzothiazole, linalool-oxide, ethyl benzanoate), or were shared by both host-plants (linalool, methyl salicylate). Sex pheromone compounds were also tested. The male response to the major pheromone component (E7,Z9-12:Ac) was higher than to any other stimuli, whereas the response to the minor pheromone components (E7,Z9-12:OH and Z9-12:Ac) was not different from the response to the plant odorants. The female response to pheromone was lower or not different from that to plant odorants. Methyl salicylate elicited a higher response in females and (E)-ß-farnesene elicited a higher response than several other plant odorants in both sexes. Non-significant interactions between host-plant odorant and sex indicated an absence of sex specialization for host-plant volatile detection. The lack of a significant interaction between plant volatiles and larval host-plants suggested that there was no specialization for plant-volatile detection between V. vinifera and D. gnidium individuals.
ABSTRACT
BACKGROUND: A binary co-occluded mixture (HearSP1B:LB6) of Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) variants was previously found to be highly pathogenic under laboratory conditions. The insecticidal efficacy and persistence of this mixture were determined in greenhouse and field-grown tomato crops in Spain and Portugal. RESULTS: Concentrations of 10(9) -10(11) occlusion bodies (OBs) L(-1) of HearSP1B:LB6 resulted in 89-100% mortality of larvae on treated tomato plants in growth chambers. In protected tomato crops, application of 10(10) OBs L(-1) of HearSP1B:LB6 was as effective as Bacillus thuringiensis (Bt) and spinosad in reducing the percentage of damaged fruits, and resulted in higher larval mortality than the Bt treatment. In open-field tomato crops, virus treatments were as effective in reducing the percentage of damaged fruit as spinosad, Bt and chlorpyrifos treatments. The persistence of the insecticides on tomato plants was negatively correlated with solar radiation in both field and greenhouse settings. Residual insecticidal activity of OBs on protected tomato crops at 6 days post-application was 55 and 35% higher than that of Bt and spinosad respectively. On field-grown tomato, OB persistence was significantly lower than with spinosad or chlorpyrifos. CONCLUSION: The efficacy and persistence of HearSP1B:LB6 OBs were comparable with those of commercial insecticides in both field and greenhouse tomato crops. Future studies should focus on reducing application rates to determine insecticidal efficacy at lower OB concentrations. © 2015 Society of Chemical Industry.
