Insect Pests In China Research Articles

Mitochondrial DNA revealed the extent of genetic diversity and invasion origin of populations from two separate invaded areas of a newly invasive pest, Cydia pomonella (L.) (Lepidoptera: Tortricidae) in China.

Cydia pomonella is a serious invasive insect pest in China, and has caused severe damage to the production of apple and pear in its invaded areas. This species is distributing in the northwest and northeast of China, but no occurrence of it has been recorded in the large areas (about 3000-5000 km away) between the invaded northwestern and northeastern regions despite continuous monitoring. As yet the genetic diversity and invasion origin of the C. pomonella populations in Northwestern and Northeastern China is obscure. In this study, we investigate the genetic diversity of 14 populations of C. pomonella sampled throughout the main distribution regions in Northwestern (Xinjiang and Gansu Provinces) and Northeastern (Heilongjiang Province) China and compared them with nine populations from Europe and other continents using the mitochondrial COI, COII and Cytb genes. Both the populations from Northeastern and Northwestern China shared some haplotypes with populations from other countries. Haplotypes of the three mitochondrial genes had a different distribution in Northeastern and Northwestern China. The northeastern populations had more private haplotypes than the northwestern populations. A large number of the individuals from northwestern populations shared a few haplotypes of each of the three genes. The haplotype numbers and haplotype diversities of the northeastern populations were similar to those of field populations in other countries, but were higher than those of the northwestern populations. Populations from the Northwestern China showed similar haplotype number and haplotype diversity. We conclude that the population genetic background of C. pomonella populations in Northeastern and Northwestern China varies due to different invasion sources and that this should be considered before the application of new pest control tactics.

Can the predatory mites Amblyseius swirskii and Amblyseius eharai reproduce by feeding solely upon conspecific or heterospecific eggs (Acari: Phytoseiidae)?

The phytoseiid mite, Amblyseius swirskii (Athias-Henriot) is an exotic biological control agent of mites and small insect pests in China. Amblyseius eharai (Amitai & Swirski), on the other hand, is a native predacious mite common throughout East and South-East Asia and considered to be an important natural enemy of Panonychus citri (McGregor). Understanding the ways introduced predators affect native ones is vital if we wish to use the former as biological control agents in the field. In order to evaluate the interactions between these two predacious mites, we observed their life histories when they cannibalized or fed upon intraguild prey under laboratory conditions. Both male and female A. eharai and A. swirskii could develop to adulthood by feeding upon both conspecific and heterospecific (IGP) eggs. However, A. swirskii females supplied with IGP eggs had shorter developmental durations, higher fecundity, and higher intrinsic rates of increase (rm) than those supplied with conspecific eggs. On the other hand, A. eharai females supplied with conspecific eggs had higher rm than those supplied with heterospecific eggs, suggesting that A. eharai females may prefer to prey upon conspecific immatures, even when A. swirskii immature stages are present. As a result, A. swirskii females may decrease A. eharai populations, when extra-guild prey species, such as spider mites, and pollen are scarce.

Rice Grain Damage by Combination and Sequence Infestations by the Rice Leaffolder, Cnaphalocrocis medinalis Guenee (Lepidoptera: Pyralidae), and the White-Backed Rice Planthopper, Sogatella furcifera Horváth (Hemiptera: Delphacidae)

The rice leaffolder (RLF), Cnaphalocrocis medinalis Guenée (Lepidoptera: Pyralidae), and the white-backed rice planthopper (WBPH), Sogatella furcifera Horváth (Hemiptera: Delphacidae), are major insect pests in China and several other Asian countries. These two pests commonly occur simultaneously or in a temporal sequence. Thus, the investigation of the effect of complex infestations or temporal sequence infestations by these pests on rice yield has a practical significance for the control of these pests. The present study comprised experiments with the following four different variables in potted rice at the tillering stage: single pest species infestation, complex infestation, complete combination infestation and temporal sequence infestation (C. medinalis infestation prior to S. furcifera and S. furcifera infestation prior to C. medinalis). The results showed that the four infestations resulted in a significant decrease in 1000-grain weight (1000GW) and rate of yield loss (RYL) but an increase in blighted grain rate (BGR), with a significant positive correlation with the infestation density. However, the influences of the complex infestation, complete combination infestation or sequence infestation on the 1000GW, BGR and RYL were greater than those of the single pest species infestations but did not have addition effects, i.e., the effects of the complex infestation and combination infestation or sequence infestation on the 1000GW, BGR and RYL were less than the additive effects of the two single pest species infestations at the same densities. In the condition of the same total infestation pressure, no significant differences in the 1000GW, BGR and RYL were found between C. medinalis infestation prior to S. furcifera and S. furcifera infestation prior to C. medinalis as well as between the sequence infestation and the complex infestation.

Effects of Heat Shock on Life Parameters ofFrankliniella occidentalis(Thysanoptera: Thripidae) F1 Offspring

Abstract The western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), an invasive insect pest in China, causes great economic losses worldwide. To understand the effects of heat shock on WFT population dynamics, we constructed life tables to quantify the effects of heat shock on the growth rate, survival, and fecundity of WFT offspring. WFT adults and 2nd instars were heat shocked at 45 °C, and the treatment was repeated after a 24-h recovery period. Heat-shocked and control insects were reared on the leaves of purple cabbage (Brassica oleracea L.; Brassicales: Brassicaceae), and various lifetable and development parameters of their F1 offspring were evaluated. The duration of the immature period of the offspring of heat-shocked adults was not significantly shorter than that of the control, whereas the duration of the immature period of the offspring of the heatshocked 2nd instars was longer than that of the other treatments, indicating that heat-shock of second instar...

Effect of synergists on susceptibility to chlorantraniliprole in field populations of Chilo suppressalis (Lepidoptera: Pyralidae).

The Asiatice stem borer, Chilo suppressalis (Walker), an important rice insect pest in China, has developed resistances to several classes of insecticides. To control C. suppressalis, chlorantraniliprole has been introduced as a novel insecticide in rice field since 2008. It is an anthranilic diamide insecticide that binds and activates ryanodine receptors (RyR). The susceptibility of field populations of C. suppressalis to chlorantraniliprole was determined in this study. The hypotheses of equality and parallelism showed that regression lines in the tested five populations were neither equal nor parallel. The Ruian, Cangnan, and Liangyungang populations (RA12, CN12, and LYG12) collected in 2012 had lower LD50 values, whereas the Zhuji populations (ZJ12 and ZJ13) collected in 2012 and 2013 were approximately 15 times more tolerant than the RA12 population. To determine the potential mechanisms involved in this tolerance variation, synergism bioassays were performed. Significant differences in susceptibility were found between without synergist and with synergist for the three populations (RA12, LYG12, and ZJ13), based on the tests for the hypotheses of equality. In RA12 and LYG12 populations with chlorantraniliprole, the addition of piperonyl butoxide (PBO) significantly synergized the activity, with synergism ratios of 2.68- and 2.33-fold, respectively, whereas addition of S,S,S-tributyl phosphorotrithioate (DEF) and diethyl maleate (DEM) had no synergist effect. In ZJ13 population with chlorantraniliprole, the addition of PBO and DEF increased synergism ratios by 12.43- and 6.31-fold, respectively, whereas addition of DEM had no significant effect on the toxicity against ZJ13 larvae. These susceptibility and synergism data suggested that detoxification enzymes might be involved in the tolerance variation to chlorantraniliprole in field populations of C. suppressalis.

Post-Mating Interactions and Their Effects on Fitness of Female and Male Echinothrips americanus (Thysanoptera: Thripidae), a New Insect Pest in China

Post-mating, sexual interactions of opposite sexes differ considerably in different organisms. Post-mating interactions such as re-mating behavior and male harassment can affect the fitness of both sexes. Echinothrips americanus is a new insect pest in Mainland China, and little is known about its post-mating interactions. In this study, we observed re-mating frequency and male harassment frequency and their effects on fitness parameters and offspring sex ratios of E. americanus females. Furthermore, we tested the impact of mating and post-mating interactions on fitness parameters of males. Our results revealed that the re-mating frequency in female adults was extremely low during a 30-day period. However, post-mating interactions between females and males, consisting mainly of male harassment and female resistance, did occur and significantly reduced female longevity and fecundity. Interestingly, increased access to males did not affect the ratio of female offspring. For males, mating dramatically reduced their longevity. However, post-mating interactions with females had no effects on the longevity of mated males. These results enrich our basic knowledge about female and male mating and post-mating behaviors in this species and provide important information about factors that may influence population regulation of this important pest species.

Reprint of: Biological control of rice insect pests in China

Rice is one of the most important food crops in the world. China has the second largest area of the rice growing in the world and the highest yield of rice produced. Infestation by insect pests, especially rice planthoppers, stem borers and leaf folders, is always a serious challenge to rice production in China. Current methods for controlling insect pests in China mainly include good farming practices, biological control, breeding and growing resistant varieties, and the use of chemical insecticides. However, for farmers, the favorite method for insect pest control is still the application of chemical insecticide, which not only causes severe environmental pollution and the resurgence of herbivores but also reduces populations of the natural enemies of herbivores. To control insect pests safely, effectively and sustainably, strategies encouraging biological control are currently demanded. Here we review the progress that has been made in the development and implementation of biological controls for rice in China since the 1970s. Such progress includes the species identification of the natural enemies of rice insect pests, the characterization of their biology, and the integration of biological controls in integrated pest management. To develop effective ecological engineering programs whose aim is to implement conservation biological controls, further research, including the evaluation of the roles of plants in non-crop habitats in conservation biological controls, volatiles in enhancing efficiency of natural enemies and natural enemies in manipulating insect pests, and education to increase farmers’ knowledge of biological controls, is proposed.

Erratum to “Biological control of rice insect pests in China” [Biol. Control, 67 (2013), pp. 8–20

Erratum to “Biological control of rice insect pests in China” [Biol. Control, 67 (2013), pp. 8–20

Biological control of rice insect pests in China

Rice is one of the most important food crops in the world. China has the second largest area of the rice growing in the world and the highest yield of rice produced. Infestation by insect pests, especially rice planthoppers, stem borers and leaf folders, is always a serious challenge to rice production in China. Current methods for controlling insect pests in China mainly include good farming practices, biological control, breeding and growing resistant varieties, and the use of chemical insecticides. However, for farmers, the favorite method for insect pest control is still the application of chemical insecticide, which not only causes severe environmental pollution and the resurgence of herbivores but also reduces populations of the natural enemies of herbivores. To control insect pests safely, effectively and sustainably, strategies encouraging biological control are currently demanded. Here we review the progress that has been made in the development and implementation of biological controls for rice in China since the 1970s. Such progress includes the species identification of the natural enemies of rice insect pests, the characterization of their biology, and the integration of biological controls in integrated pest management. To develop effective ecological engineering programs whose aim is to implement conservation biological controls, further research, including the evaluation of the roles of plants in non-crop habitats in conservation biological controls, volatiles in enhancing efficiency of natural enemies and natural enemies in manipulating insect pests, and education to increase farmers’ knowledge of biological controls, is proposed.

Biological control of arthropod pests in citrus orchards in China

China has a very long history of biological control in citrus. Hundreds years ago, predatory ants (Oecophylla smaragdina Fabricius) were used to manage pests by Chinese citrus growers. Considerable effort has been placed on the use of biological control in citrus plant landscapes during last three decades. Many scientific studies have now been published, and some additional implementations have already working. In this paper, we review the research, development and application of biological control of citrus insect pests in China. In addition, the importance of biological control for the future control of citrus insect pests is also discussed.

Isolation and characterization of Aschersonia placenta from citrus orchards and its pathogenicity towards Dialeurodes citri (Ashmead)

For selecting potential biological agents to control Dialeurodes citri, a major insect pest in China’s citrus orchards, 75 native Aschersonia isolates were selected from infected whiteflies in citrus orchards and were evaluated for virulence to third instar nymphs of D. citri at a concentration of 1×106conidia/ml. The mortality rates of D. citri varied from 0% to 72.70%. Among the 75 Aschersonia isolates, three (HB10, HB12 and ZJ9) were the most virulent and pathogenic to D. citri and caused more than 69% mortality. The 50% lethal concentration (LC50) values of them were 1.86×106, 3.40×106 and 6.81×106conidia/ml, respectively. The three isolates also produced conidia abundantly on potato dextrose agar medium (3.95×106, 6.19×106 and 7.34×106conidia/cm2, respectively). They were identified to be Aschersonia placenta based on their morphological analysis. Phylogenetic analysis showed that these three highly virulent Aschersonia isolates belong to a strongly supported clade that includes two other A. placenta isolates obtained from Vietnam and Thailand. In summary, these results indicate the possibility of developing the three most virulent A. placenta isolates as microbiological control agents against citrus whitefly.

Baculoviruses and insect pests control in China

China is rich in insect viruses. Helicoverpa armigera nucleopolyhedrovirus (HaSNPV), was the first commercial insecticide registered in 1993. Subsequently, 13 viral insecticides were registered and released into the market as pesticides, including nine nucleopolyhedrovirus (NPV), three granulovirus (GV), one densonucleosis virus (DNV), and one cytoplasmic polyhedrosis virus (CPV). Industrial exploitation of viruses in China started more than three decades ago. To date, at least 24 baculovirus insecticides have been or are currently used in field trials in China, 12 of which are unregistered. Examples of successful applications and benefits of entomopathogenic viruses as microbial insecticides are presented in the current paper. However, chemical prevention is still the main measure for the management of insect pests in China. Effective public extension services, government policies, and farmer education are important to expand the use of viral insecticides as well as for the further development in the production and use of these insecticides. Key words: Microbial control, baculoviruses, viral insecticide, sustainable agriculture.

Migratory Adaptations in <I>Chrysoperla sinica</I> (Neuroptera: Chrysopidae)

The green lacewing Chrysoperla sinica (Tjeder) (Neuroptera: Chrysopidae) is a common natural enemy of various insect pests in China and is frequently employed for augmentation biological control. Adults of this species perform migration flights after emergence, the nature of which affects its value for biological control program. In this manuscript, we report characteristics of C. sinica migratory populations captured during 2008-2009 using a light trap at Beihuang Island (Bohai Gulf), 40-60 km from mainland China, and their relationships with flight performance. In total, 1,452 migratory C. sinica adults were caught for these 2 yr. Throughout the sampling period, migratory populations consisted of >50% female individuals, most of which were in preoviposition period and had low degrees of ovarian development. During autumn, most migratory females were unmated. C. sinica females began oviposition since 7 d after emergence. Flight mill tests showed that 5-d-old females in preoviposition period flew over the longest distance (i.e., 4.50 ± 1.31 km) over 8 h and mating status did not affect flight performance. For 3-d-old individuals, males flew over larger distances than females, and unmated individuals exhibited stronger flight capability than mated ones. Hence, gender, mating status, and age all determine C. sinica flight performance. Based upon those findings, we can indicate that C. sinica migratory populations appear adapted to long-distance flights. This research should help understand C. sinica population dynamics and aid its incorporation within integrated pest management (IPM) packages for several crops.

Flight Mill Performance of the Lacewing Chrysoperla sinica (Neuroptera: Chrysopidae) as a Function of Age, Temperature, and Relative Humidity

The lacewing Chrysoperla sinica (Tjeder) (Neuroptera: Chrysopidae) is an important predator of several insect pests in China and has considerable potential as a biological control agent. An inoculative approach would be the releasing adults early in the season to ensure that populations are present before pest densities increase. However, an understanding of adult flight activity under different conditions is necessary to develop appropriate release strategies. Therefore, we used a 32-channel, computer-monitored flight mill system to determine the effect of age on the flight activity of unmated female and male adults. Both sexes had high total flight activity levels as well as the longest individual flight bouts 2 and 3 d after emergence. The effects of temperature (between 13 and 33 degrees C at 75% RH) and relative humidity (between 30 and 90% RH at 23 degrees C) on the flight activity of 3-d-old unmated adults also were determined. Flight activity declined at the lowest (13 degrees C) and highest (33 degrees C) temperatures tested, as well as at the lowest relative humidity (30% RH). These findings are discussed within the context of selecting the appropriate environmental conditions for releasing C. sinica.

Lethal Effect and In Vivo Genotoxicity of Profenofos to Chinese Native Amphibian (Rana spinosa) Tadpoles

Amphibian populations are decreasing in size due to environmental stressors in most areas of southern China. Pesticides are known to be a group of potential stressors to amphibians, especially in agricultural ecosystems. Profenofos, an organophosphate insecticide and acaricide, is widely used for controlling insect pests in China. The aim of this study is to evaluate the acute lethality and genotoxicity of profenofos to amphibian under controlled conditions. Results showed that profenofos was highly lethal to tadpoles of Rana spinosa, with 50% lethal concentration (LC(50)) values of 1.59, 1.14, 0.77, and 0.58 mg l(-1) at 24, 48, 72, and 96 h, respectively. DNA damage of erythrocytes was observed by alkaline single-cell gel electrophoresis assay at all tested sublethal concentrations. The study also showed, by micronucleus test, that profenofos at moderate to high sublethal concentration might have genotoxicity to the tadpole after 96 h exposure. Furthermore, based on our results, it is suggested that the alkaline single-cell gel electrophoresis assay could be used as a screening tool for biomonitoring of pesticide contamination in aquatic systems or agricultural ecosystems.

The Cost of Mating

The Cost of Mating