Synthesis and insecticidal activity of new pyrethroids

BACKGROUND: Pyrethroids are among the most potent pesticides known, with great potential for structural variation with retention or enhancement of potency. The simple methyl ester is easier to prepare (at least one step shorter) than the more complex pyrethroids modified on the alcohol moiety. The objective was to synthesise methyl esters of pyrethroid acids containing an aromatic ring on the acid moiety and evaluate their biological activity against Ascia monuste orseis Latr., Tuta absoluta Meyrick, Periplaneta americana (L.), Musca domestica L. and Sitophilus zeamais (Motsch.). RESULTS: The synthetic sequence required seven steps: protection of the hydroxyl groups of D ‐mannitol, diol oxidative cleavage with sodium metaperiodate, alkene formation by Wittig reaction with methoxycarbonylmethylidene(triphenyl)phosphorane, cyclopropanation, acetal hydrolysis with perchloric acid and oxidative cleavage with sodium metaperiodate gave methyl (1S, 3S)‐3‐formyl‐2,2‐dimethylcyclopropane‐1‐carboxylate. The final step comprised reaction of the aldehyde with five different aromatic phosphorus ylides to give the pyrethroids. CONCLUSION: An efficient and versatile synthesis of ten new pyrethroid methyl esters has been accomplished from the readily available D ‐mannitol in seven steps. All compounds showed insecticidal activity, and methyl (1S, 3S)‐3‐[(Z)‐2‐(4‐chlorophenyl)vinyl]‐2,2‐dimethylcyclopropane‐1‐carboxylate was the most active, killing 90% of A. monuste orseis and 100% of T. absoluta and P. americana. Copyright © 2009 Society of Chemical Industry     

Does Thyrinteina arnobia (Lepidoptera: Geometridae) use different defense behaviours against predators?

Journal of Plant Diseases and Protection - The efficiency of biological control programs with predators depends on knowing defense behaviour of caterpillars to avoid or to reduce predation. The...     

A new lupene triterpenetriol and anticholinesterase activity of Salvia sclareoides

A new lupene triterpenetriol was isolated from the acetone extract of the aerial parts of Salvia sclareoides and characterised as (1beta,3beta)-lup-20(29)-ene-1,3,30-triol (1). In addition, nepetidin (2), nepeticin (3), lupendiol (4), (1beta,11alpha)-dihydroxy-lup-20(29)-en-3-one (5), ursolic acid (6), sumaresinolic acid (7) and hederagenin (8), were identified in this Salvia sp. To the best of our knowledge, the compounds 2 and 7 are new constituents in Salvia spp. The acetone, ethanol, butanol and water extracts of the plant were screened for the in vitro inhibitory activity of acetylcholinesterase (AChE) and butyrilcholinesterase (BChE), enzymes which play a role in the Alzheimer disease. All extracts inhibited acetylcholinesterase activity at 10 microg/ml, a remarkable activity since the standard drug rivastigmine does not inhibit acetylcholinesterase at the same concentration. Regarding the butyrilcholinesterase, the acetone extract at 1000 microg/ml was able to inhibit completely the enzyme activity and the butanol and ethanol extracts, at this concentration, produced a potent inhibition of BchE.     

Linalool production from the leaves of Bursera aloexylon and its antimicrobial activity

The oil of the leaves of Bursera aloexylon was found to contain a high linalool level (96.7 %). The antimicrobial activity tests indicated that the oil was effective against Rhodococcus equi (0.60 mg/ml) and Staphylococcus epidermides (0.15 mg/ml).     

Bioactivity of extracts and isolated compounds from Vitex polygama (Verbenaceae) and Siphoneugena densiflora (Myrtaceae) against Spodoptera frugiperda (Lepidoptera: Noctuidae)

The effects of crude extracts, fractions and isolated compounds from Vitex polygama Cham. and Siphoneugena densiflora Berg were evaluated on the development of Spodoptera frugiperda JE Smith, a destructive insect pest of corn and several other crops. The extracts and fractions were incorporated into an artificial diet at 1 mg g(-1) and offered to the insect during its larval stage. Length and viability of larval and pupal stages as well as pupal weight were assessed. Isolated compounds were tested through superficial contamination of the diet at 0.1 mg g(-1). Weight and viability of ten-day-old larvae were determined. Methanolic and hydroalcoholic S. densiflora extracts caused 100% larval mortality, while leaf and fruit hydroalcoholic extracts from V. polygama were the most active. Among the isolated compounds, flavonoids presented the best insecticidal results, and tannins the best larval growth inhibition.     

Identifying risk factors for European stone fruit yellows from a survey

ABSTRACT European stone fruit yellows (ESFY) is becoming a major economic problem for Prunus growers in Europe. The causal agent ("Candidatus Phytoplasma prunorum") and its vector (Cacopsylla pruni) have been identified, but the present knowledge of the risk factors for this disease relies, at best, on specific experiments. To assess the relative significance of several factors correlated with ESFY incidence in the field, an exhaustive survey was performed on apricot and Japanese plum orchards in the Crau plain (France). After a preliminary multivariate exploration of the data, we used a logistic regression model to analyze and predict the cumulative number of diseased trees on the basis of a set of quantitative (age, planting density, and area of the orchard) and categorical variables (species, cultivar, and rootstock). Because of the nature of the data, we used an overdispersed binomial model and we developed a parametric bootstrap procedure based on the beta-binomial distribution to obtain confidence intervals. Our results indicated that the age, species, and cultivar of the scion were the major factors explaining the observed number of diseased trees. The planting density and the rootstocks used in the zone under study were less significant, and the area of the orchard had no effect. The residuals of the model showed that some explanatory variables had not been taken into account, because part of the remaining variability could be explained by a grower effect. The spatial distribution of the residuals suggested that one of the reasons for this grower effect was the correlation between orchards closer than 100 m, possibly caused by the flight behavior of infectious vectors.     

Unraveling evolutionary relationships among the divergent lineages of colletotrichum causing anthracnose disease in turfgrass and corn

ABSTRACT Colletotrichum species cause anthracnose diseases on a number of grass hosts and are common inhabitants of many others. They are divided into four species: C. sublineolum is pathogenic to Sorghum spp.; C. caudatum is found on C4 grasses such as indiangrass and big bluestem; C. falcatum causes red rot of sugarcane; and C. graminicola sensu lato is a broadly defined species including isolates that attack maize, wheat, oats, and many forage, turf, and amenity grasses of the subfamily Pooideae. In this paper, a combination of hierarchal- and nonhierarchal-based analyses were employed to examine evolutionary relationships among the grass-infecting Colletotrichum species, with special emphasis on isolates from turf and other grasses in the subfamily Pooideae. Reconstructions performed with data sets from over 100 Colletotrichum isolates at three variable loci using phylogenetic and network-based methodologies unambiguously supported the taxonomic separation of maize-infecting isolates of C. graminicola from the pooid-infecting strains of Colletotrichum. To reflect the evolutionary relationships that exist between these distinct lineages, we propose the resurrection of the species name C. cereale to describe the pooid-infecting isolates. There was also support for further subdivision of C. cereale, but the current data are insufficient to confidently subdivide the species, as there was some evidence of recombination between lineages of this species.     

Drying and wetting of Mediterranean soils stimulates decomposition and carbon dioxide emission: the "Birch effect"

Observations on the net carbon exchange of forests in the European Mediterranean region, measured recently by the eddy covariance method, have revived interest in a phenomenon first characterized on agricultural and forest soils in East Africa in the 1950s and 1960s by H. F. Birch and now often referred to as the "Birch effect." When soils become dry during summer because of lack of rain, as is common in regions with Mediterranean climate, or are dried in the laboratory in controlled conditions, and are then rewetted by precipitation or irrigation, there is a burst of decomposition, mineralization and release of inorganic nitrogen and CO(2). In forests in Mediterranean climates in southern Europe, this effect has been observed with eddy covariance techniques and soil respiration chambers at the stand and small plot scales, respectively. Following the early work of Birch, laboratory incubations of soils at controlled temperatures and water contents have been used to characterize CO(2) release following the rewetting of dry soils. A simple empirical model based on laboratory incubations demonstrates that the amount of carbon mineralized over one year can be predicted from soil temperature and precipitation regime, provided that carbon lost as CO(2) is taken into account. We show that the amount of carbon returned to the atmosphere following soil rewetting can reduce significantly the annual net carbon gain by Mediterranean forests.     

Rapid Identification of Clavibacter michiganensis Subspecies Sepedonicus based on the Stable Low Molecular Weight RNA (LMW RNA) Profiles

Clavibacter michiganensis subsp. sepedonicus causes potato ring rot disease. The identification process for this bacterium is complex and long. This work demonstrates that the stable low-molecular-weight (LMW) RNA profiles allow their rapid identification. Staircase electrophoresis in polyacrylamide gels was used to analyze the LMW RNA profiles of 54 strains of C. michiganensis subsp. sepedonicus from different geographic origins. The profiles of several strains of other subspecies of C. michiganensis and other pathogens of potatoes were also analyzed. All the strains of C. michiganensis subsp. sepedonicus had the same LMW RNA profile. They had a band in class 2 of tRNA that was absent in the other subspecies of the species C. michiganensis. Also, the LMW RNA of C. michiganensis subsp. sepedonicus was different with respect to the LMW RNA profiles of other pathogens of potato. The results indicate the possible utilization of LMW RNA profiles in identification of the bacteria causing potato ring rot disease.     

Control of Cyclohexane Atmospheric Emissions During Soil Remediation

Gaseous effluent from the treatment of contaminated soils must becontrolled to avoid atmospheric emissions of volatile organiccompounds during remediation. The combination of carbonadsorption with catalytic deep oxidation for control ofcyclohexane emissions is analysed in this paper. The activitiesof activated carbons prepared with almond shells and impregnatedwith CoO, Co₃O₄ and CrO₃ were compared, inrelation with carbon structure, catalyst content and catalystspecies. The microcatalytic-chromatographic technique developedwas very suitable for rapid comparison of the catalyticactivities. Carbons with a better development of surface areaand pore volumes showed higher catalytic activities. Theincreasing of catalyst content also increased catalyticactivity. Cobalt is better than chromium to catalyse the deepoxidation of cyclohexane, the oxidation state of cobalt inCo₃O₄ being better than in CoO.