Freilanduntersuchungen über Ausschlüpfen,Begattung und Eiablage beim Springwurmwickler (Sparganothis pilleriana Schiff.)

Journal of Pest Science -     

The antihistaminic chlorpheniramine inhibitsin vitro growth of several fungi isolated from harvested fruits

Chlorpheniramine (CPA) is an antihistaminic that changes the conformation of DNA and inhibits polyamine biosynthesis in mammalian cells. In the present work, we tested the effect of CPA on four genera of fungi species (Altemaria alternata, Botrytis cinerea, Cladosporium cladosporioides and threePenicillium spp.) grownin vitro. Similar growth inhibitions of these genera were produced by 0.5 raM iprodione, CPA and histidinol, but CPA was the most effective. The CPA sensitivities of the twoB. cinerea strains were different. Putrescine did not restore the fungal growth inhibited by CPA.     

Distribution and diversity of leaf-cutting ants in Northeastern Argentina: species most associated with forest plantations

Abstract

Leaf-cutting ants (LCA) are considered one of the main herbivores and one of the most destructive pest insects of the Neotropics. Northeastern Argentina harbors the greatest species richness of these ants and in turn comprises the highest surface with forest plantations. Our aim was to establish which species of leaf-cutting ants are most commonly associated with forest plantations by analyzing their geographic distribution using published and unpublished species occurrence data. Also, estimate their potential areas of distribution along a latitudinal gradient that entirely encompasses northeastern Argentina using Ecological Niche Modeling. Only seven of the 20 species recorded were strongly associated with productive systems along the gradient, but only 2–3 species in each region could be considered high-risk species for forest plantations. High-risk species composition shows a turnover between regions. Our models show the potential distribution areas where LCA could become more abundant and dominant, and possibly causing a detrimental effect on the forest plantations in the studied region. We find that ecological niche models are useful tools to assess the environmental suitability of important LCA.     

Effects of huanglongbing on fruit quality of sweet orange cultivars in Brazil

Citrus huanglongbing (HLB), associated with Candidatus Liberibacter asiaticus and Ca. L. americanus and transmitted by the Asian psyllid Diaphorina citri, is the most serious disease of citrus worldwide because of crop devastation and difficulty to control. Since 2004, approximately 3 million trees were eliminated in attempts to limit its spread in Brazil. Where HLB becomes endemic, the disease progression in the orchard and the increasing symptom severity throughout the tree canopy can be relatively fast, greatly reducing the economic life of affected orchards because of tree decline and yield reduction. Although the majority of the fruit from symptomatic branches drop before harvest, a significant amount of affected fruit remain attached, are available for harvest, and can affect juice quality. To quantify and compare the effects of HLB on fruit quality of the most important sweet orange cultivars grown in São Paulo State, 4–6 year-old sweet orange trees from 26 blocks (two of ‘Valencia Americana’, eight of ‘Hamlin’, four of ‘Westin’, seven of ‘Pera’, and five of ‘Valencia’) were selected prior to harvest. In each block, 14–21 HLB-symptomatic trees were chosen. In each tree, the quality of 20 fruit normal in appearance from asymptomatic branches and 20 symptomatic fruit from symptomatic branches were assessed. In general, compared to normal fruit, the symptomatic fruit were small, light, more acidic, and had lower juice percentage, Brix, total soluble solids per box, total soluble solids per fruit, and Brix/acidity ratio. These effects of fruit quality were less pronounced on early and mid season sweet orange cultivars than on late season cv. Valencia.     

Resistance to polyoxin AL and other fungicides in Botrytis cinerea collected from sweet basil crops in Israel

A total of 568 B. cinerea isolates were collected from diseased sweet basil plants and the air in 10 sweet basil greenhouses. Mycelial growth tests were used to evaluate the sensitivity of these isolates to benomyl, fenhexamid, iprodione, polyoxin AL and pyrimethanil. EC₅₀ values for polyoxin, the main botryticide on sweet basil in Israel, ranged from 0.4 to 6.5 μg ml^?1 and had a bimodal distribution; the EC₅₀ values for sensitive isolates ranged from 0.4 to 1.5 μg ml^?1 and the EC₅₀ values for low-level resistant isolates ranged from 4 to 6.5 μg ml^?1. Among populations that had not been exposed to polyoxin treatments, 20 to 35 % of the collected isolates were low-level resistant for polyoxin. Polyoxin treatments in an experimental greenhouse shifted the equilibrium in favour of low-level resistant isolates, and the change occurred rapidly: from a frequency of 20 % low-level resistant isolates in the population that had never been treated with polyoxin to a frequency of 72 % after a few treatments over two seasons. Prolonged use of polyoxin in Israeli basil crops (in some sites for more than 10 years) does not appear to have led to the development of high-level resistance, but low-level resistant isolates were found in commercial greenhouses with the frequency of up to 73 %. High-level resistance to benzimidazoles was common (60 to 80 % of isolates) in greenhouses with a history of benzimidazole treatments; whereas 15–25 % of the isolates from greenhouses in which fungicides were not used were resistant. Low-level resistance to dicarboximides was fairly widespread (frequency of 30 to 80 % depending on the greenhouse) and a few cases of moderate resistance to dicarboximides were also noted (frequency of 0 to 9 %). Neither high- nor low-level resistance to anilinopyrimidines was common in sweet basil commercial greenhouses (0 to 7 %). However, 34 % of the isolates were strongly resistant in the experimental greenhouse, following a few treatments with anilinopyrimidine fungicides during the previous season. Before those treatments, the proportion of anilinopyrimidines resistant isolates had been 1 %. About 3 % of the isolates exhibited low-level resistance to fenhexamid and no isolates were found to be strongly resistant to fenhexamid. Low-level resistance to one fungicide was often associated with low-level resistances to other fungicides. Thirty-two phenotypes exhibiting resistance to one or more of the tested fungicides were noted among B. cinerea isolates. Resistant isolates showed similar or reduced fitness parameters in comparison to wild-type isolates.