Time filter

Source Type

Fang G.,General Station of Forest Pest Control
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011

Chironomids are a globally-distributed family of insects that can serve as biological indicators of environmental pollution. Pollution due to pesticide usage is of particular importance due to the heavy application of these chemicals. Three routinely-applied insecticides, omethoate, chlorpyrifos, and cyhalothrin, were selected for our study to investigate their toxicity against Propsilocerus akamusi and to determine their effects on carboxylesterase activity of 4th-instar larvae. After 12 h of exposure, the LC 50 values of omethoate, chlorpyrifos and cyhalothrin were 12. 508, 2. 478, and 0. 046 μg/L, respectively, indicating cyhalothrin has the highest level of toxicity to P. akamusi. The omethoate induced carboxylesterase activity at 3 and 12 h post-application when P. akamusi was challenged with 0. 05 μg/L. When challenged with the higher rates, 0. 05, 0. 125, 0. 25, 0.5, 1, 2 and 4 μg/L of omethoate, carboxylesterase activity was found to increase after 48 h. In addition, carboxylesterase activity was inhibited at 24 h and 48 h for the 0. 05 μg/L of omethoate while enzyme inhibition was observed for the earlier time points of 3, 12 and 24 h for all doses tested. The inhibition carboxylesterase activity ranged from 5. 149% -50.587% and 3.225%-36.403% under treatments with 0. 125, 0. 25, 0. 5, 1, 2, 4, and 8 μg/L at 3 and 12 h, respectively. Overall, at 24 h, the inhibition of carboxylesterase activity by omethoate ranged from 20.441% 48. 523%. In comparison, when chlorpyrifos was applied with the concentration of 0. 125, 0. 25, 1, 2 and 4 μg/L, the level of carboxylesterse was inhibited dramatically after 3 h treatment. This trend was also found at 12 h with the exception of the lower concentrations of 0. 125 and 0. 25 μg/L. Overall, the inhibition of carboxylesterase was found by the treatment of chlorpyrifos with the concentration of 0. 125, 0. 25, 1,2 and 4 μg/L ranged from 14. 145% 51. 254% at 24 h and 9. 772%-39. 659% at 48 h. For the cyhalothrin test, carboxylesterase activity was inhibited by 0. 00625, 0. 0125, 0. 05, 0. 25, and 1 μg/L of cyhalothrin treatments at 3, 12,24, and 48 h. The magnitude of the inhibition caused by cyhalothrin was found to be decreased following the cyhalothrin concentrations and treatment time. The differences in the carboxylesterase activities caused by omethoate, chlorpyrifos, and cyhalothrin indicated different responses of P. akamusi to different dose and time of these insecticides. The poisoning symptoms also indicated differences between the three insecticides tested. The symptoms of P. akamusi to omethoate and chlorpyrifos poisons in P. akamusi were overall excitation followed by a loss of consciousness and ultimately death. The poisoning symptoms of P. akamusi to cyhalothrin, however, showed an initial increase in activity followed by a period of inactivity, apparent recovery and finally death. These results suggest that the carboxylesterase activity of chironomids can be used as a biochemical marker to monitor pesticide pollution.

Baumgartner K.,University of California at Davis | Baker B.R.,Middle Tennessee State University | Korhonen K.,Finnish Forest Research Institute | Zhao J.,General Station of Forest Pest Control | And 4 more authors.
Fungal Biology | Year: 2012

Populations of Armillaria mellea (Basidiomycota, Agaricales) across much of its range are heterothallic; homothallic populations occur only in Africa (A. mellea ssp. africana), China (China Biological Species CBS G), and Japan (A. mellea ssp. nipponica). Monosporous isolates of heterothallic A. mellea are haploid and their mating behaviour is consistent with the requirement of two different alleles at two mating-type loci (tetrapolar mating system) to create a diploid individual. In contrast, monosporous isolates of homothallic A. mellea are putatively diploid; they bypass the haploid phase by undergoing karyogamy in the basidium (a unique type of secondary homothallism/pseudohomothallism). In order to determine the genetic origin of this homothallism, we analyzed genetic variation of 47 heterothallic isolates from China, Europe, and North America, and 14 homothallic isolates from Africa, China, and Japan. Gene trees and mutational networks were constructed for partial mitochondrial gene ATP synthase subunit 6 (ATP6) and for the following nuclear genes: actin (ACTIN), elongation factor subunit 1-alpha (EFA), glyceraldehyde 3-phosphate dehydrogenase (GPD), and the RNA polymerase subunit II (RPB2). Homothallic isolates from Africa and Japan shared a common mitochondrial ATP6 haplotype with homothallic isolates from China, and are likely introductions. Homothallic isolates from China that shared a common mitochondrial haplotype with all European isolates did not share European nuclear haplotypes, as revealed by median-joining networks, but instead clustered with haplotypes from China or were intermediate between those of China and Europe. Such mitochondrial-nuclear discordance in homothallic isolates from China is indicative of hybridization between lineages originating from China and Europe. © 2012 British Mycological Society.

Guo T.,CAS Kunming Institute of Botany | Guo T.,University of Chinese Academy of Sciences | Wang H.C.,Chongqing Normal University | Xue W.Q.,Chongqing Normal University | And 2 more authors.
PLoS ONE | Year: 2016

Fungal species of Armillaria, which can act as plant pathogens and/or symbionts of the Chinese traditional medicinal herb Gastrodia elata ("Tianma"), are ecologically and economically important and have consequently attracted the attention of mycologists. However, their taxonomy has been highly dependent on morphological characterization and mating tests. In this study, we phylogenetically analyzed Chinese Armillaria samples using the sequences of the internal transcribed spacer region, translation elongation factor-1 alpha gene and beta-tubulin gene. Our data revealed at least 15 phylogenetic lineages of Armillaria from China, of which seven were newly discovered and two were recorded from China for the first time. Fourteen Chinese biological species of Armillaria, which were previously defined based on mating tests, could be assigned to the 15 phylogenetic lineages identified herein. Seven of the 15 phylogenetic lineages were found to be disjunctively distributed in different continents of the Northern Hemisphere, while eight were revealed to be endemic to certain continents. In addition, we found that seven phylogenetic lineages of Armillaria were used for the cultivation of Tianma, only two of which had been recorded to be associated with Tianma previously. We also illustrated that G. elata f. glauca ("Brown Tianma") and G. elata f. elata ("Red Tianma"), two cultivars of Tianma grown in different regions of China, form symbiotic relationships with different phylogenetic lineages of Armillaria. These findings should aid the development of Tianma cultivation in China. © 2016 Guo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Yang S.,Southwest forestry University | Zhang B.,Southwest forestry University | Zhuang X.,Southwest forestry University | Xia J.,Southwest forestry University | Chai S.,General Station of Forest Pest Control
Journal of the Entomological Research Society | Year: 2014

The mortality rate of overwintering population of the pine bark-weevil, Pissodes punctatus and causes of mortality were examined on newly infested host trees in Northeast Yunnan Province of China. We found an 80.76% mortality rate of P. punctatus that was greatly higher than the healthy (survival) rate. Life stages of overwintering population of this pest were overlapping including older larvae (3rd-4th instar) (71.20%), pupae (16.47%) and adults (12.32%). The causes of mortality were identified into different biotic factors, which included woodpecker predation, parasitism by insect parasitoids, tree resistance and undetermined diseases. Predation by woodpeckers (41.83%) was the dominant factor causing the mortality of immature stages of P. punctatus and significantly higher than the parasitism by insect parasitoids (18.99%), tree resistance (17.97%) and undetermined diseases (1.98%). Moreover, three hymenopteran ectoparasitoids (Triaspis sp., Rhopalicus sp. and Eurytoma sp.) were observed to attack immature stages of P. punctatus. Triaspis sp. was the dominant species amounting 70.59% of the parasitoids, indicating a high potential in the biological control programme of P. punctatus. Relevance of these findings to biological control associated with forest management of P. punctatus was discussed.

Ge S.-L.,Northeast Forestry University | Cao C.-W.,Northeast Forestry University | Fang G.-F.,General Station of Forest Pest Control | Wang Z.-Y.,Northeast Forestry University
Chinese Journal of Applied Ecology | Year: 2011

Taking the 4th-instar larval Propsilocerus akamusi as test object, this paper studied the acute toxicity of phenol, and the body mass, pupation rate, protective enzyme activities, and detoxifying enzyme activities of the larvae under exposure to phenol. The LC 50 value of phenol to the larvae after exposure for 6, 24, 48, 72, and 96 h was 222.52, 134.86, 67.74, 47.39, and 35. 76 mg · L -1 , respectively, and the dry mass, fresh mass, and pupation rate of the larvae decreased under the exposure of 0. 4, 4, and 40 mg phenol ·L -1. During 72 h exposure to phenol, the larval catalase (CAT) , superoxide dismutase (SOD) , glutathione S-transferase (GST) , and carboxylesterase (CarE) activities responded to phenol in concentration- and time-dependent way, while the acid phosphatase (ACP) and alkaline phosphatase (ALP) activities responded slowly and were only inhibited significantly under the exposure to 40 mg · L -1 of phenol for 48 and 72 h, respectively. It was suggested that the body mass, pupation rate, and CAT, SOD, GST, and CarE activities of 4th-instar larval P. akamusi could be used as the biological markers to monitor the phenol pollution of water body.

Discover hidden collaborations