Sublethal effects of abamectin on the development, fecundity, and wing morphs of the brown planthopper Nilaparvata lugens

Hong Yang,Cao Zhou,Dao-chao Jin,Ming-fu Gong,Zhao Wang,Gui-yun Long 한국응용곤충학회 2019 Journal of Asia-Pacific Entomology Vol.22 No.4

The brown planthopper Nilaparvata lugens negatively affects rice yield by sucking nutrients from the rice stem and spreading viruses. In this study, the effects of sublethal concentrations of abamectin on development, fecundity, and wing morphs of N. lugens were investigated. Treatment with sublethal concentrations of abamectin showed no significant effects on the developmental period of F 0 nymphs. Although LC 10 and LC 25 treatments resulted in 10% and 25% mortality, the LC 25 treatment significantly prolonged the lifespan of macropterous and brachypterous females. Abamectin-treated brachypterous females showed significantly lower fecundity than control females. Furthermore, abamectin treatment showed no significant effects on the developmental period of F 1 nymphs. However, LC 25 treatment significantly inhibited the fecundity of brachypterous F 1 females and significantly reduced the proportion of macropterous F 1 females and brachypterous F 1 males. LC 25 treatment showed no significant effects on the fecundity of macropterous F 1 females. Considering the proportion of macropterous and brachypterous F 1 females, the relative fitness of the macropterous F 1 nymphs in the control, LC 10 , and LC 25 treatment groups was 1, 1.02, and 0.84, respectively, and that of brachypterous F 1 nymphs was 1, 0.79, and 0.93, respectively. Sublethal concentrations of abamectin inhibited N. lugens emergence. The present findings indicate the potential of abamectin for N. lugens field control.

Research Progress on Leptotrombidium deliense

Yan Lv,Xian-Guo Guo,Dao-Chao Jin 대한기생충학열대의학회 2018 The Korean Journal of Parasitology Vol.56 No.4

A New Species of Chigger Mite (Acari: Trombiculidae) from Rodents in Southwest China

Tian-Guang Ren,Xian-Guo Guo,Dao-Chao Jin,Dian Wu,Quinn E. Fletcher 대한기생충학열대의학회 2014 The Korean Journal of Parasitology Vol.52 No.1

Relative Abundance of a Vector of Scrub Typhus, Leptotrombidium sialkotense, in Southern Yunnan Province, China

Yan Lv,Xian-Guo Guo,Dao-chao Jin,Wen-Yu Song,Rong Fan,Cheng-Fu Zhao,Zhi-Wei Zhang,Ke-Yu Mao,Yun-Ji Zou,Zhi-Hua Yang 대한기생충학ㆍ열대의학회 2020 The Korean Journal of Parasitology Vol.58 No.2

The chigger mite Leptotrombidium sialkotense is one of the 6 main vectors of scrub typhus in China. Before present study, L. sialkotense was found in some parts of Hunan province, China with a narrow geographical distribution. During field investigation 2016-2017, we found L. sialkotense in Jingha, southern Yunnan, China. Of 15 small mammal host species, L. sialkotense were collected from 6 species of the hosts. Rattus brunneusculus was a dominant host of L. sialkotense, from which 98.3% of the mites were collected. The chigger mite showed a relatively high infestation prevalence (PM=11.7%) and mean abundance (MA=0.5) in comparison with the rest 5 host species. These results reveal a certain host specificity of L. sialkotense to a rat R. brunneusculus. The mite L. sialkotense showed an aggregated distribution on the host (P<0.05). A positive correlation observed between L. sialkotense and the body length of hosts. There was a positive interspecific association between L. sialkotense and 2 other dominant vectors, L. deliense and L. scutellare.

Sublethal effects of buprofezin on development, reproduction, and chitin synthase 1 gene (SfCHS1) expression in the white-backed planthopper, Sogatella furcifera (Hemiptera: Delphacidae)

Zhao Wang,Cao Zhou,Gui-yun Long,Hong Yang,Dao-chao Jin 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.2

The white-backed planthopper, Sogatella furcifera (Horváth) (Hemiptera: Delphacidae), is a major rice pest in some Asia-Pacific countries. Buprofezin is an insect growth regulator with relatively low mammalian toxicity but high efficacy to many rice pests. In this study, we estimated the toxicity of buprofezin against 3rd-instar nymphs of S. furcifera using the rice-stem dipping method. The results showed that the LC50 of buprofezin to 3rd-instar nymphs were 0.89 mg/L. When 3rd-instar nymphs were exposed to the LC10 and LC25 (0.10 and 0.28 mg/L) of buprofezin, the duration of juvenile development was significantly prolonged in the F0 and F1 generations. The fecundity (eggs per female) of the F1 females was reduced by 5.29% and 12.34%, respectively, in addition to the survival rate, emergence rate, copulation rate, and hatchability were decreased by treatment with buprofezin at LC10 and LC25, compared with the control group. The relative fitness of S. furcifera in LC10 and LC25 treatments was reduced by 47% and 63%, respectively. Furthermore, real-time quantitative PCR analyses revealed increased the expressions of SfCHS1 and its two variants following the exposure of nymphs to buprofezin. Increased these genes mRNA levels associated with reduced chitin biosynthesis may result from the inhibition of chitin synthase activity, and thereby leading to a higher mortality of S. furcifera. Overall, sublethal concentrations of buprofezin suppressed the population growth of S. furcifera.

Expression of three neuropeptide genes (SfEH, SfETH, and SfCCAP) in response to insecticide stress on the white-backed planthopper Sogatella furcifera (Hemiptera: Delphacidae)

Long Gui-yun,Wang Zhao,Yang Jia-peng,Tang Chen-hong,Jin Dao-Chao,Yang Hong,Zhou Cao,Yang Xi-bin 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.3

Insect neuropeptides are involved in many important developmental processes. Here, we cloned three neuro peptide genes (SfEH, SfETH, and SfCCAP) from Sogatella furcifera (Horváth) and analyzed the relative expression levels of these genes through Real-time Quantitative polymerase chain reaction (RT-qPCR) during different developmental stages and in different wing types of S. furcifera following exposure to sublethal concentrations (LC 10 and LC 25 ) of methylaminoavermectin benzoate. The results revealed that the three neuropeptide genes (SfEH, SfETH, and SfCCAP) of S. furcifera contained open reading frame sequences of 222, 636, and 408 bp, encoding 73, 211, and 135 amino acids, respectively. Moreover, the expression of SfEH and SfETH reached its peak on day 3 of the 5 th instar nymph stage, while the SfCCAP expressed pinnacle on 40 min after eclosion. Furthermore, the relative expression levels of the three genes were in the following order: SfEH, short-winged female > long-winged female > long-winged male; SfETH, long-winged female > short-winged female > longwinged male; and SfCCAP, short-winged female > long-winged male > short-winged female. Upon calculating the relative expression of the three peptide genes after 24 and 48 h of treatment with sublethal concentrations of methylaminoavermectin benzoate, it was found that the relative mRNA expression levels of SfEH and SfETH declined upon LC 10 treatment but increased upon LC 25 treatment. Meanwhile, the relative mRNA expression level of SfCCAP declined upon both LC 10 and LC 25 treatments. This result will help us understand the effects of pesticides on insect growth and development at the molecular level.

Sublethal effects of imidacloprid on the development, reproduction, and susceptibility of the white-backed planthopper, Sogatella furcifera (Hemiptera: Delphacidae)

Cao Zhou,Lei-lei Liu,Hong Yang,Zhao Wang,Gui-yun Long,Dao-chao Jin 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.3

Sogatella furcifera (Horváth) (white-backed planthopper, WBPH) is one of the most important pests on rice in Asia. It seriously impacts rice production by sucking phloem from the rice plant and transmitting southern rice black-streaked dwarf virus (SRBSDV). In the current study, we examined the sublethal effects of imidacloprid on the development, reproduction, and susceptibility of S. furcifera in the laboratory using the rice stem dipping method. The results showed that exposure of third-instar S. furcifera nymphs to sublethal concentrations (LC10 and LC25) of imidacloprid inhibited the rate of nymphal development in the F0 and F1 generations, and there was a significant difference between the LC25 treated group and the control group. The fecundity (eggs per female) of the F1 generation showed significant declines of 22.05% and 38.56% following exposure to LC10 and LC25, respectively compared with the control group. Emergence rate, copulation rate, and hatchability were significantly lower in the LC25-treated group. The relative fitness of S. furcifera treated with LC10 and LC25 imidacloprid was 0.46 and 0.22, respectively. These results showed that exposure to imidacloprid impacted the next generation of S. furcifera, thus affecting the population growth of this species. After third-instar S. furcifera nymphs were exposed to sublethal concentrations of imidacloprid LC10 and LC25, S. furcifera showed reduced susceptibility to treatment with thiamethoxam and buprofezin. Although the susceptibility of S. furcifera to chlorpyrifos was decreased after the exposure of third-instar nymphs to imidacloprid LC25, S. furcifera populations that had been exposed to imidacloprid LC10 showed enhanced susceptibility to chlorpyrifos. These results provided a reference point for the application of insecticides to control S. furcifera.

Cloning and differential expression of three heat shock protein genes associated with thermal stress from the wolf spider Pardosa pseudoannulata (Araneae: Lycosidae)

Sun Liang-Yu,Liu Jing,Li Qin,Fu Di,Zhu Jia-Yun,Guo Jian-Jun,Xiao Rong,Jin Dao-Chao 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.1

Pardosa pseudoannulata is the main predatory natural enemy of crop pests in a paddy ecosystem. When P. pseudoannulata is exposed to unfavorable temperature conditions, the response of heat shock proteins could resist the damage, and is therefore, conducive to the organism’s rapid adaptation to the surrounding stress environ ment. In this study, we explored the roles of hsp70 and hsp90 genes in response to heat stress, using the rapid amplification of cDNA ends technique and cloned full-length cDNAs of Pphsp70, Pphsp83, and Pphsp90. The mRNA expression levels of the three genes under different temperature stresses (25, 28, 31, 34, 37, 40, and 43 ◦ C) and with different duration stresses (4, 8, 12, 16, and 20 h) were analyzed by quantitative real-time polymerase chain reaction. The full-length cDNA of Pphsp70, Pphsp83, and Pphsp90 was 2331 base pair (bp), 2466 bp, and 2663 bp, respectively. Phylogenetic analysis of amino acid sequences of Pphsp70, Pphsp83, and Pphsp90 showed that the sequences had high homology with that of other spiders. The mRNA expression of all three genes was extremely significantly up-regulated at 43 ◦ C. Moreover at 43 ◦ C, the expression of all three genes in both female and male spiders at the duration of 4 h was the highest compared to that of other stress duration groups. Therefore, it can be inferred that the three genes of P. pseudoannulata play a crucial protective role in resistance in a high-temperature environment.

Disease vector occurrence and ecological characteristics of chiggers on the chestnut white-bellied rat Niviventer fulvescens in Southwest China between 2001 and 2019

Yan-Ling Chen,Xian-Guo Guo,Wen-Yu Song,Tian-Guang Ren,Lei Zhang,Rong Fan,Cheng-Fu Zhao,Zhi-Wei Zhang,Wenge Dong,Xiao-Bin Huang,Dao-chao Jin 대한기생충학ㆍ열대의학회 2023 The Korean Journal of Parasitology Vol.61 No.3

Chigger mites are the vector of scrub typhus. This study estimates the infestation status and ecological characteristics of chiggers on the chestnut white-bellied rat Niviventer fulvescens in Southwest China between 2001 and 2019. Chiggers were identified under the microscope, and infestation indices were calculated. The Preston’s log-normal model was used to fit the curve of species abundance distribution. A total of 6,557 chiggers were collected in 136 of 342 N. fulvescens rats, showing high overall infestation indices (prevalence=39.8%, mean abundance=19.2, mean intensity=48.2) and high species diversity (S =100, H’=3.0). Leptotrombidium cangjiangense, Neotrombicula japonica, and Ascoschoengastia sifanga were the three dominant chigger species (constituent ratio=42.9%; 2,736/6,384) and exhibited an aggregated distribution among different rat individuals. We identified 100 chigger species, with 3 of them (Leptotrombidium scutellare, Leptotrombidium wenense, and Leptotrombidium deliense) as the main vectors of scrub typhus in China and nine species as potential vectors of this disease. Disease vector occurrence on N. fulvescens may increase the risk of spreading scrub typhus from rats to humans. Chigger infestation on N. fulvescens varied significantly in different environments. The species abundance distribution showed a log-normal distribution pattern. The estimated number of chigger species on N. fulvescens was 126 species.