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1.
Grapholita molesta, a worldwide fruit-boring pest, is difficult to be effectively controlled due to the larvae feeding habit inside fruits. Neuropeptide F (NPF) is the crucial molecule modulating feeding behavior of insects. Herein, two genes, NPF1 and NPF2, were identified and cloned from G. molesta. GmolNPF1 had a higher expression in newly hatched larvae than in other developmental stages and mainly in the midgut (major expressive organ). Coincidentally, the stage of newly hatched larvae was the best control period to prevent larvae from entering the fruits. Further study demonstrated that only GmolNPF1 expression increased significantly after starvation and declined after refeeding. After GmolNPF1 knockdown by RNA interference (RNAi), the feeding amount, weight, body size and drill holes rate of larvae decreased significantly, and the number of larvae that ate food within 5 min declined significantly. The pET30-NPF1-BL21(DE3) RNase III system was successful constructed and produced large batch dsRNA (double stranded, ds) of GmolNPF1. The nanocarrier-mediated transdermal dsRNA delivery system enhanced the RNAi efficiency of dsNPF1, significantly decreased the fruit damage and increased the mortality of newly hatched larvae via spraying method. Our research not only revealed the regulation function of GmolNPF1 involved in the feeding behavior of G. molesta, but also showed the NPF1 as a molecular target combined the transdermal dsRNA delivery system will a potential control strategy for pest management in the field. 相似文献
2.
Bacillus thuringiensis (Bt), a naturally occurring entomopathogenic soil bacterium, has been the active ingredient of sprayable Bt biopesticides for over a century. Insecticidal Bt Cry proteins are particularly well suited for use as plant-incorporated protectants in transgenic crops (Bt crops) due to their specificity against insect pests and safety for non-target organisms. The sustainability of these Bt products, however, has been challenged by the development of resistance in the field. RNA interference (RNAi), a species-specific control alternative that has been deregulated and commercialized in the USA and Canada, provides a new mode of action to complement the existing Bt products. Based on our preliminary research, we hypothesized that pyramiding/integrating Bt with RNAi can address/manage resistance issues related to Bt traits. To examine this overarching hypothesis, we (1) cloned and characterized a serine/threonine kinase gene (fused) of the Hedgehog (Hh) signaling pathway in the diamondback moth, Plutella xylostella (L.), a global superpest; (2) profiled Pxfused expression in Bt-resistant P. xylostella strains; and (3) investigated the involvement of Pxfused in Bt Cry1Ac resistance in P. xylostella. Pxfused expression was elevated ubiquitously in all Bt-resistant strains, and silencing of Pxfused led to larval and pupal mortality in both Cry1Ac-susceptible and -resistant strains, suggesting that Pxfused is a potential target for RNAi-based resistance management. Taken together, our results not only identify a molecular target to control a devastating lepidopteran pest, but also shed light on a novel resistance management strategy through the integration of two biotechnological techniques with distinct modes of action. 相似文献
4.
Transgenic Bt-cotton now dominates the cotton-growing belt in northwestern China where there are few natural plant refuges to act as sources of moths susceptible to Bt toxin. As an initial step towards developing an insect resistance management (IRM) plan for the pest moth, Helicoverpa armigera, on Bt-cotton in this part of China, we assessed the potential of six crops grown in two configurations to act as refuge hosts for susceptible moth production in both broad-acre and small-holder farms. Egg and larval abundance indicated that H. armigera had a preference for chickpea, pigeon pea, and corn, over cotton, sorghum, and benne (sesame). There were no significant differences in egg or larval abundance between plot and strip configurations of these crop hosts. We found that sorghum was not attractive to H. armigera, contrary to the findings in other cotton production areas. Moreover, chickpea, pigeon pea, and corn were determined to be potential refuge hosts based on egg and larval abundance over the growing season. From the adult moth population dynamics in broad-acre and small-holder farms, the efficiency of alternative refuge crops, and local agricultural practices, we recommend that spring corn be grown as a strip crop as part of an IRM strategy to improve the probability of Bt-susceptible moth production and mating with resistant moths in broad-acre farms. In small-holder farms where current agricultural practices are entrenched, wheat and summer corn should be evaluated as refuge crops in the future. 相似文献
5.
Pest management strategies relying on agrochemicals could be altered by climate change, because of the temperature-dependent toxicity of the compound involved. Many studies have explored the response of targeted pests to pesticide and temperature. Pesticides are seldom strictly selective and also affect nontarget pests. Surprisingly, the way temperature may shape these side effects of pesticides remains overlooked, limiting our understanding of the net impacts of future chemical treatments on the overall damage induced by different pests. We investigated how temperature modulates the response of a major grape insect pest (the tortricid moth Lobesia botrana) to a copper-based fungicide. We examined the lethal (larval survival) and sublethal (larval development, pupal mass, immune parameters) effects of exposure to different concentrations of copper in larval food. We found that copper concentration had negative linear effects on larval development and pupal mass. In addition, copper concentration had biphasic curvilinear effects on total phenoloxidase activity, which is indicative of hormesis (stimulation and inhibition of insect performance at low and high copper concentrations, respectively). Temperature stimulated development, while compromising immunity (total phenoloxidase activity). Significant interaction between copper concentration and temperature was detected for larval survival and phenoloxidase activity: warmer conditions improved pest tolerance to copper through temperature-driven hormesis (larval survival) or by shifting the hormesis-related peak of performance toward higher copper concentrations (phenoloxidase activity). This combination of simple and interactive effects could propagate to populations, communities and agroecosystem, with implications for future management of viticultural pests. 相似文献
6.
The nontarget effects of three plant growth stimulants (gibberellic acid, Siapton and triacontanol) and two plant growth retardants
(chlormequat chloride and mepiquat chloride) on the survivorship and developmental parameters of Spilarctia obliqua Walker (Lepidoptera: Arctiidae) were studied. For each compound, various concentrations (0.125×, 0.25×, 0.5×, × , 2× and
4×; × = labeled dose) bracketing the labeled dose were prepared by serial dilution and mixed with an artificial diet for the
insect. Gibberellic acid caused an increase in the larval period at × − 4×, but no marked difference was observed in the pupal
period or in larval survival at any concentration. Siapton induced a significant increase in larval period at the two highest
doses but caused significant reduction in pest survival at × − 4×. Interestingly, triacontanol induced a significant reduction
in pest survivorship at almost all doses. The LC 50 for triacontanol was 0.206% and LT 50 was 266.5 hours at the labeled dose. However, triacontanol did not cause any significant difference in larval or pupal periods
at any dose tested. Chlormequat chloride and mepiquat chloride caused significant reduction of larval survivorship at concentrations
higher than the labeled doses, and no effect on the larval period. Intriguingly, a significant reduction in pupal period was
observed with chlormequat chloride at × and 0.25×. Based on the marked effect of triacontanol on pest survivorship, this study
suggests incorporating triacontanol in integrated pest management modules for S. obliqua. Caution in the use of gibberellic acid and Siapton for pest infestations is also indicated. 相似文献
7.
The effect of various host plants; chickpea (varieties Arman, Hashem, Azad and Binivich), bean varieties ( Phaseolus vulgaris L.), common bean (Khomein), white kidney bean (Dehghan), red kidney bean (Goli), cowpea (variety Mashhad) and tomato (variety Meshkin) on the life table parameters of the cotton bollworm, Helicoverpa armigera (Hübner) were evaluated under laboratory conditions (25 ± 1 °C, 65 ± 5 % RH and a 16:8 h light:dark photoperiod). Records for larval period, pupal period, and development time of H. armigera were longest on tomato (24.9, 15.1, and 45.4 days, respectively) and shortest on chickpea Arman (17.5, 9.1, and 31.7 days, respectively). Among various host plants fecundity (total number of eggs laid per female) was highest (2,665 eggs) on chickpea Arman and the lowest (700 eggs) on tomato. The net reproductive rate ( R 0) was significantly affected by various host plants being highest on chickpea Arman (1,422) and lowest on tomato (111.3 females/female/generation). The highest and lowest intrinsic rates of natural increase ( r m) were observed on chickpea Arman (0.244 day ?1) and tomato (0.123 day ?1) varieties, respectively. Cluster analysis of the life table parameters of H. armigera on various host plants indicated that tomato, in comparison to other plants was an unsuitable host to H. armigera. 相似文献
8.
[目的]构建白蜡虫(Ericerus pela)蜡酯合酶(wax synthase,WS)基因干扰载体并建立其体外dsRNA(doublestranded RNA,dsRNA)原核表达体系,低成本大量制备白蜡虫ws基因的dsRNA。[方法]克隆白蜡虫蜡酯合酶基因ws片段,连入L4440载体,将重组质粒转入大肠杆菌HT115感受态细胞,经IPTG诱导获得与目的片段相对应的dsRNA。[结果]白蜡虫ws基因RNA干扰(RNA interference,RNAi)载体成功构建,重组质粒转入HT115感受态细胞经IPTG诱导后菌体成功表达dsRNA,dsRNA的平均获得量1 705 ng·m L~(-1)。[结论]该研究通过原核表达白蜡虫ws基因的dsRNA,为后续利用RNAi实验研究白蜡虫ws基因功能及作用机理奠定基础。 相似文献
9.
Kaolin particle films and copper-based products can be considered as possible alternatives to traditional agrochemicals used for controlling the dominant pest of olive grove areas of the Mediterranean Basin, the olive fruit fly, Bactrocera oleae (Rossi) (Dip. Tephritidae), to which this pest has already evolved resistance. Psyttalia concolor (Szèpligeti) (Hym. Braconidae) is a koinobiont larval–pupal endoparasitoid of many Tephritidae of economic importance. It has been routinely used in the Mediterranean Basin for augmentative releases against B. oleae. Detailed knowledge of lethal and sublethal effects of these agrochemicals on non target arthropods is required for effective integrated pest management programmes. The aims of this study were to evaluate direct mortality caused by kaolin and copper salts on the parasitoid and the sublethal effects on emergence of adults from treated pupae and on beneficial capacity of females through four different experiments, three at laboratory level and one in semi-field conditions. Dual choice and no-choice experiments in the case of kaolin were also performed to test kaolin oviposition repellence. The results indicated that the tested agrochemicals were not harmful to the parasitoid. No lethal toxicity or effects on beneficial capacity were recorded. The behavioural experiments, however, showed that when females could choose between parasitising through a kaolin-treated surface and a water-treated one, there was a slight reduction in the percentage of parasitised hosts for kaolin. No differences were detected when females were not given a choice. 相似文献
10.
The cotton bollworm Helicoverpa armigera is a destructive pest that affects a variety of crop plants. Because of its polyphagous feeding habit, mobility as adults, and high fecundity, the expanding infestations of H. armigera in different crops have caused economic losses and difficulties for pest population management. In Brazil, a sequence of different crop systems in the same area and crop rotation during the year can create a spatio-temporal mosaic of crops where H. armigera can persist. However, the consequences of the simultaneous and/or alternating presence of host plants for H. armigera populations through generations are unknown. In this study, we simulated, in the laboratory, hypothetical situations for the availability of soybean and cotton crops in the landscape. We evaluated the effects of: (1) the number of generations during which a population feeds on a host-plant species; (2) the succession of host-plant species on which populations have fed for two generations; and (3) the parental host plant on the fitness of H. armigera populations. Only the current host plant on which larvae fed affected the performance of the H. armigera populations. Decrease of mortality rates during the immature period was slowed when the larvae fed on soybean. The lowest value of reproductive potential ( R 0) was found for individuals originating from mating between females and males reared in cotton. Our results indicated that pest-management and biological-control plans for H. armigera should be developed on a regional scale rather than for just a specific crop area. 相似文献
11.
Bactrocera minax is a major citrus pest in China, Bhutan, and India. It is univoltine and exhibits pupal diapause during winter. To better understand pupal diapause in this pest, we investigated pupal survival and pupal developmental duration under field and laboratory conditions. Specifically, we tested if pupal chilling was required for diapause development and termination. Nearly all mature larvae collected at the end of the citrus season entered pupal diapause. For pupae exposed in the field, natural chilling for less than 3 months resulted in more than 70 % mortality. However, exposure to winter conditions for 3 months or more both decreased pupal mortality and developmental duration when pupae were returned to the laboratory and held under constant temperature (25 °C). When pupae were gathered from the field in November and exposed to different chilling regimes in the laboratory, the chilling duration (30 vs 60 days) had significantly more impact on pupal survival than the specific chilling temperature (6, 8, 10, or 12 °C constant). However, both chilling duration and chilling temperature impacted on the pupal developmental duration, with longer chilling duration and higher temperatures decreasing pupal developmental duration. In conclusion, we demonstrated that pupal diapause development and termination in B. minax is strongly influenced by chilling conditions. Increasing cold exposure led to significantly and consistently faster adult eclosion and improved synchronization of adult emergence. This knowledge will help with the laboratory rearing of B. minax, an essential step in the long-term management of this pest. 相似文献
12.
The pollen beetle Brassicogethes aeneus is a serious pest of oilseed rape (Brassica napus) in Europe. Management of this pest has grown difficult due to B. aeneus’s development of resistance to pyrethroid insecticides, as well as the pressure to establish control strategies that minimise the impact on nontarget organisms. RNA interference represents a nucleotide sequence-based, and thus potentially species-specific, approach to agricultural pest control. The present study examined the efficacy of targeting the coatomer gene coatomer subunit alpha (αCOP), via both microinjection and dietary exposure to exogenous complementary dsRNA, on αCOP-silencing and subsequent mortality in B. aeneus. Beetles injected with dsRNA targeting αCOP (at 0.14 µg/mg) showed 88% and 100% mortality at 6 and 10 days post-injection, respectively; where by the same time after dietary exposure, 43%–89% mortality was observed in the 3 µg dsRNA/µL treatment, though the effect was concentration-dependent. Thus, the effect was significant for both delivery routes. In working towards RNA-based management of B. aeneus, future studies should include αCOP as a target of interest. 相似文献
15.
Twenty-eight spotted potato ladybird beetle ( Henosepilachna vigintioctopunctata) is a polyphagous pest that infests various crop plants of the family Solanceae. It extensively infests Withania somnifera, a high-value medicinal plant of this family. Both the beetle and W. somnifera leaf spot pathogen ( Alternaria alternata) are individually found to be closely associated with the foliar damage and may rarely infest the same leaf simultaneously. Beetles fed on diseased leaves showed high pupal and larval mortality. Furthermore, the development of the larvae into pupa and from pupa to adult was also delayed, which in turn delayed the overall development of the insect. Adult emergence from pupae is also reduced in the insects fed on diseased leaves. Since the fungal pathogen is host specific to W. somnifera and does not infect the other solanaceous crops, therefore this fungal stain can be used in designing bio-control strategies for the other solanaceous plants frequently infested by the beetle. 相似文献
16.
目前使用的神经毒剂杀虫剂,通常以神经膜上的钠通道、乙酰胆碱酯酶或者神经递质受体作为靶标位点,如拟除虫菊酯类、氨基甲酸酯类及烟碱类杀虫剂.但长期单一使用某一种杀虫剂,昆虫往往会对其产生抗药性.对付害虫抗性的最棘手问题是因某个作用靶标部位对某种杀虫剂不敏感而产生抗性后,对以前即使没有使用过的同类杀虫剂也会产生抗性,即产生交互抗性(cross resistance).因此,寻找具有不同杀虫机理的新农药是控制抗性害虫的一条重要途径. 相似文献
17.
Plusia acuta, hitherto reported as a minor pest of soybeans, now has become its a regular and serious pest in Madhya Pradesh, India. During kharif season of 1979 it infested severely about 10 hectares of soybeans in Jabalpur, Madhya Pradesh, India. Research was, thus, carried out to work out its biology in the laboratory in 1979. Single female moth laid 97.6 eggs in its life span on both the surface of leaves and some times on tender petiole and petiolets. The incubation, larval, prepupal and pupal periods lasted for about 4, 14, 1 and 7 days, respectively. Total life cycle completed in 24.8 days. Male and female moths lived for 5.6 and 4.8 days, respectively. The percentage emergence of adults was 73.8 in the laboratory. 26.3 percent larvae were found parasitized in fields. 相似文献
18.
RNA interference （RNAi）, a process that inhibits gene expression by the double-stranded RNA （dsRNA）, causes the degradation of target messenger RNA molecules. RNAi exists in almost all organisms. We review the recent history of RNAi studies, RNAi molecular mechanisms, characteristics and RNAi applications in higher plants. At the same time, the prospect of RNAi applications in functional genomics and genetic improvement of higher plants and possible future problems and possibilities are also discussed. 相似文献
19.
[目的]为了构建松材线虫( Bursaphelenchus xylophilus)果胶酶 Bxpel2基因干扰载体. [方法]通过Trizol 法提取松材线虫总RNA,反转录合成cDNA,设计带T 7启动子的果胶酶 Bxpel2基因引物,以cDNA为模板扩增出果胶酶 Bxpel2基因片段,连接到RNA干扰载体,再以干扰载体为模板,PCR扩增出目的片段后进行测序鉴定,合成果胶酶 Bxpel2基因双链RNA(dsRNA),采用RT-PCR检测松材线虫 Bxpel2基因干扰后的表达情况. [结果]表明:1)提取的松材线虫总RNA完整性好,无降解;2)成功克隆出松材线虫果胶酶 Bxpel2基因片段(790 bp)并将其连接至pMD19-T载体;3)以RNA干扰载体为模板合成dsRNA,浓度分别为1.313 mg·mL -1和1.152 mg·mL -1;4)RT-PCR结果显示,松材线虫经过dsRNA干扰后, Bxpel2基因表达基本受到抑制. [结论]成功构建松材线虫果胶酶 Bxpel2基因干扰载体,为进一步研究Bxpel2基因在松材线虫致病过程中的作用和功能奠定了良好的基础. 相似文献
20.
Methanolic extract of Melia azedarach fruits enriched by washing with petrolether and ethyl acetate was used for laboratory treatments of two lepidopteran pests in Egypt. The experiments were carried out with concentrations of 10, 15, 25, 50, 100 and 1000 ppm in a diet and compared with control insects. In both insects food consumption, weight gain and conversion of ingested food (ECI) in body matter decreased with increasing extract amounts. The conversion of digested food (ECD) was lowered gradually by using higher concentrations of Melia extract. Some antifeedant activity was observed in larvae of S. littoralis and A. ipsilon. The percentage of mortality increased with application of higher concentrations of Melia extract in both species. Starting from 3rd larval instar the larvae of both species reduced significantly their weight until pupation in 25 ppm and higher extract concentrations, while the larval period was prolonged. The pupal weight was significantly reduced at 15, 25 and 50 ppm. At higher concentrations the larvae failed to pupate. Duration of pupal period was affected only in A. ipsilon. All reproduction parameters, as period of oviposition, fecundity, fertility and longevity of males and females were affected using emerged adults from treated larvae with concentrations of 10, 15 and 25 ppm Melia extract. In S. littoralis no adult emerged from pupae originated from larvae treated with 50 ppm and higher amounts and no larva hatched from eggs laid by adults treated with 25 ppm Melia concentration as larvae. In both species the oviposition period was shortened at 15 and 25 ppm extract, the fecundity and fertility were drastically reduced, and the longevity of males and females was reduced. Cross sections of the midgut showed that the epithelial cells are destroyed in both pests. This can be one of the reasons for the observed effects. 相似文献
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