Synergism of insecticides provides evidence of metabolic mechanisms of resistance in the obliquebanded leafroller Choristoneura rosaceana (Lepidoptera: Tortricidae)

The interactions between six insecticides (indoxacarb, cypermethrin, chlorpyrifos, azinphosmethyl, tebufenozide and chlorfenapyr) and three potential synergists, (piperonyl butoxide (PBO), S,S,S-tributyl phosphorotrithioate (DEF) and diethyl maleate (DEM)) were studied by dietary exposure in a multi-resistant and a susceptible strain of the obliquebanded leafroller, Choristoneura rosaceana (Harris). The synergists did not produce appreciable synergism with most of the insecticides in the susceptible strain. Except for tebufenozide, PBO synergized all the insecticides to varying degrees in the resistant strain. A very high level of synergism by PBO was found with indoxacarb, which reduced the resistance level from 705- to 20-fold when PBO was administered alone and to around 10-fold when used in combination with DEF. DEF also synergized indoxacarb, cypermethrin, chlorpyrifos, azinphosmethyl and tebufenozide in the resistant strain. DEM produced synergism of indoxacarb, chlorpyrifos, azinphos-methyl and chlorfenapyr in the resistant strain. DEM was highly synergistic to cypermethrin, and to some extent to tebufenozide in both the susceptible and resistant strains equally, implying that detoxification by glutathione S-transferases was not a mechanism of resistance for these insecticides. The high level of synergism seen with DEM in the case of cypermethrin may be due to an increase in oxidative stress resulting from the removal of the antioxidant, glutathione. These studies indicate that enhanced detoxification, often mediated by cytochrome P-450 monooxygenases, but with probable esterase and glutathione S-transferase contributions in some cases, is the major mechanism imparting resistance to different insecticides in C. rosaceana.     

The use of two complementary DNA assays,AFLP and MLSA,for epidemic and phylogenetic studies of pectolytic enterobacterial strains with focus on the heterogeneous species Pectobacterium carotovorum

Amplified fragment length polymorphism (AFLP) markers and multilocus sequence analysis (MLSA) were used to analyse 63 bacterial strains, including 30 soft‐rot‐causing bacterial strains collected from Syrian potato fields and 33 reference strains. For the MLSA, additional sequences of 41 strains of Pectobacterium and Dickeya, available from the NCBI GenBank, were included to produce a single alignment of the 104 taxa for the seven concatenated genes (acnA, gapA, proA, icd, mtlD, mdh and pgi). The results indicate the need for a revision of the previously classified strains, as some potato‐derived Pectobacterium carotovorum strains were re‐identified as P. wasabiae. The strains that were classified as P. carotovorum during the analyses demonstrated high heterogeneity and grouped into five P. carotovorum highly supported clusters (PcI to PcV). The strains represented a wide range of host plants including potatoes, cabbage, avocados, arum lilies, sugar cane and more. Host specificity was detected in PcV, in which four of the six strains were isolated from monocotyledonous plants. The PcV strains formed a clearly distinct group in all the constructed phylogenetic trees. The number of strains phylogenetically classified as subspecies ‘P. c. subsp. brasiliensis’ in PcIV dramatically increased in size as a result of the characterization of new isolates or re‐identification of previous P. carotovorum and P. atrosepticum strains. The P. carotovorum strains from Syria were grouped into PcI, PcII and PcIV. This grouping indicates a lack of correlation between the geographical origin and classification of these pathogens.     

Resistance to Pseudomonas syringae in a collection of pea germplasm under field and controlled conditions

A total of 242 Pisum accessions were screened for resistance to Pseudomonas syringae pv. pisi under controlled conditions. Resistance was found to all races, including race 6 and the recently described race 8. Fifty‐eight accessions were further tested for resistance to P. syringae pv. syringae under controlled conditions, with some highly resistant accessions identified. Finally, a set of 41 accessions were evaluated for resistance to P. syringae pv. pisi and pv. syringae under spring‐ and winter‐sowing field conditions. R2, R3 and R4 race‐specific resistance genes to P. syringae pv. pisi protected pea plants in the field. Resistance sources to race 6 identified under controlled conditions were ineffective in the field. Frost effects were also evaluated in relation to disease response. Results strongly suggest that frost tolerance is effective in lowering the disease effects caused by P. syringae pv. pisi and pv. syringae under frost‐stress conditions, even in the absence of disease resistance genes, although the highest degree of this protection is reached when frost tolerance and disease‐resistance genes are combined in the same genetic background.     

Aerosol delivery of trail pheromone disrupts the foraging of the red imported fire ant,Solenopsis invicta

BACKGROUND: The fire ant, Solenopsis invicta, is one of the most aggressive and invasive species in the world. The trail pheromone Z,E‐α‐farnesene (91% purity) was prepared, and disruption of worker trail orientation was tested using an ethanol‐based aerosol formulation presenting a single puff of this compound by airbrush and compressed air. Trail‐following behaviour was recorded by overhead webcam and ants digitised before and after presentation of the aerosol treatment at four rates (1.6, 16, 160 and 1600 ng cm^?2). RESULTS: Ants preferred 110 ng cm^?1 over 11, 1.1 and 0.11 ng cm^?1 for trail following. Within seconds of presentation of 1600 ng cm^?2, the highest dose tested, trail disruption was observed. Disruption was evident as reduced arrival success and reduction in the trail integrity statistic (r²), as well as increased deviation from the trail (deg). The distribution of walking track angles was also flattened. CONCLUSIONS: The feasibility of using aerosol for delivery of trail pheromone was demonstrated, but the need for high purity combined with the difficulty of commercial supply makes this technique impractical. However, the commercial production of Z,E‐α‐farnesene of high purity by industrial biotechnology or from (E)‐nerolidol may be possible in future, which would facilitate further development of trail pheromone disruption of S. invicta. Copyright © 2012 Society of Chemical Industry     

Design, synthesis, insecticidal activity and structure-activity relationship of 3,3-dichloro-2-propenyloxy-containing phthalic acid diamide structures

BACKGROUND: Phthalic acid diamide derivatives are among the most important classes of synthetic insecticides. In this study, a 3,3‐dichloro‐2‐propenyloxy group, the essential active group of pyridalyl derivatives, was incorporated into phthalic acid diamide derivatives with the aim of combining the active groups to generate more potent insecticides. RESULTS: Thirty‐one new phthalic acid diamides were obtained, and these were characterised by ¹H and ¹³C NMR. The structure of N²‐[1,1‐dimethyl‐2‐(methoxy)ethyl]‐3‐iodo‐N¹‐[4‐(3,3‐dichloro‐2‐propenyloxy)‐3‐(trifluoromethyl)phenyl]‐1,2‐benzenedicarboxamide was determined by X‐ray diffraction crystallography. The insecticidal activities of the compounds against Plutella xylostella were evaluated. The title compounds exhibited excellent larvicidal activities against P. xylostella. Structure‐activity relationships revealed that varying the combination of aliphatic amide and aromatic amide moieties, or the nature and position of substituent Y on the aniline ring, could aid the design of structures with superior performance. CONCLUSION: A series of novel phthalic acid diamides containing a 3,3‐dichloro‐2‐propenyloxy group at the 4‐position of the aniline ring were designed and synthesised. Structure‐activity relationships with the parent structure provided information that could direct further investigation on structure modification. Copyright © 2012 Society of Chemical Industry     

Laryngeal rhabdomyoma in a dog

A 3‐year‐old, female spayed Australian Shepherd dog was presented to Veterinary Healthcare Associates in Winter Haven, FL with a history of respiratory stridor, difficulty swallowing, and a change in bark for approximately 3 months. Radiographs revealed a soft tissue mass caudal to the epiglottis. Oral and computerized tomographic (CT) examinations were performed under general anesthesia and revealed a small firm mass in the caudal larynx on the right side. Cytologic evaluation of a fine‐needle aspirate of the mass revealed cells consistent with a rhabdomyoma, oncocytoma, or granular cell tumor. Histopathologic interpretation was rhabdomyoma or oncocytoma. Histochemical staining with periodic acid‐Schiff was mostly negative with a low number of weakly positive cells and with phosphotungstic acid‐hematoxylin was strongly positive with visible cross striations. Tumor cells did not express pancytokeratin AE1/AE3, were strongly immunoreactive for myoglobin and muscle‐specific actin, and did not express vimentin except for a low number of weakly immunoreactive cells. These findings confirmed a diagnosis of rhabdomyoma. Primary neoplasia of the larynx is rare, and widely varying types of neoplasms have been documented in this location. Due to the cytologic and histologic similarities between rhabdomyoma, oncocytoma, and granular cell tumor, these neoplasms should be differentiated using histochemical staining and immunohistochemical analysis.     

Pulmonary fibrosis and gammaherpesvirus infection in horses

Pulmonary fibrosis is a devastating and often progressive condition leading to exercise intolerance and frequently the demise of the animal. Although uncommonly encountered in horses, the condition is intensely researched both in human medicine and animal models. Viral infections have long been suspected to play a part in the development of pulmonary fibrosis and neoplastic conditions in other species. In 2007, an association between equine herpesvirus 5 (EHV‐5) infection and nodular pulmonary fibrosis in horses was suggested and the name equine multinodular pulmonary fibrosis (EMPF) was introduced. Recently, the presence of EHV‐5 in equine lymphoma has also emerged. The case report by Schwarz et al. in this issue describes a horse suffering from concurrent T cell leukaemia and EMPF in association with EHV‐5. This article summarises current knowledge about EMPF and EHV‐5 infections in horses, recent developments in the understanding of pulmonary fibrosis in man and the proposed contribution of viral infections to pulmonary fibrosis and neoplastic conditions.