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1.
Crops producing insecticidal crystal (Cry) proteins from the bacterium, Bacillus thuringiensis (Bt), are an important tool for managing lepidopteran pests on cotton and maize. However, the effects of these Bt crops on non-target organisms, especially natural enemies that provide biological control services, are required to be addressed in an environmental risk assessment. Amblyseius andersoni (Acari: Phytoseiidae) is a cosmopolitan predator of the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae), a significant pest of cotton and maize. Tri-trophic studies were conducted to assess the potential effects of Cry1Ac/Cry2Ab cotton and Cry1F maize on life history parameters (survival rate, development time, fecundity and egg hatching rate) of A. andersoni. We confirmed that these Bt crops have no effects on the biology of T. urticae and, in turn, that there were no differences in any of the life history parameters of A. andersoni when it fed on T. urticae feeding on Cry1Ac/Cry2Ab or non-Bt cotton and Cry1F or non-Bt maize. Use of a susceptible insect assay demonstrated that T. urticae contained biologically active Cry proteins. Cry proteins concentrations declined greatly as they moved from plants to herbivores to predators and protein concentration did not appear to be related to mite density. Free-choice experiments revealed that A. andersoni had no preference for Cry1Ac/Cry2Ab cotton or Cry1F maize-reared T. urticae compared with those reared on non-Bt cotton or maize. Collectively these results provide strong evidence that these crops can complement other integrated pest management tactics including biological control.  相似文献   

2.
Whiteflies Bemisia tabaci (Gennadius) and Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae) are important pests in pepper (Capsicum annuum L.) and tomato (Solanum lycopersicum L.) crops in many countries. Contrary to what is observed for all other countries, in Uruguay, B. tabaci is mainly found on pepper and rarely on tomato, while T. vaporariorum is exclusively found on tomato. This study tested the oviposition preferences and biotic potential of these two whiteflies reared on both host plants. The developmental time, survival rates, longevity, fecundity and main population parameters were characterized. Both whitefly species showed different preference patterns regarding their host plants. T. vaporariorum preferred tomato instead of pepper to oviposit. Their developmental time is longer on pepper. B. tabaci preferred pepper, but the difference from tomato was not very strong. Pepper affects the biotic expression of T. vaporariorum negatively, while B. tabaci is able to develop equally on both host plants. These results show that the distribution differences of both whiteflies observed on both host plants could have a biological basis.  相似文献   

3.
The sweet potato Ipomoea batatas (L.) Lam., which has extrafloral nectaries, was visited by nine indigenous ant species in south Kyushu, Japan. These ant species were evaluated for their ability to remove the eggs of two lepidopteran species—Aedia leucomelas (Linnaeus) and Spodoptera litura (Fabricius)—through ant-exclusion experiments. The results showed that Tetramorium bicarinatum (Nylander), one of the dominant ant species, is an efficient predator of lepidopteran eggs. This ant species removed A. leucomelas eggs from ant-visited plants in six trials conducted from mid-July to mid-October, with high removal rates (90–100%) occurring from mid-September onward. On ant-excluded plants, only 0–18% of exposed eggs were removed by ants that accidentally invaded the plants. Tetramorium bicarinatum also removed egg masses and the hatchlings of S. litura. The mean percent area of egg-laden leaves eaten by S. litura larvae was lower on ant-visited plants (0.9%) than on ant-excluded plants (57.3%). In contrast, Formica japonica Motschulsky, another dominant ant species, was not observed removing the eggs or larvae of the lepidopteran species. These results show that certain indigenous ant species are efficient as biocontrol agents. Thus, individual ant species need to be investigated for their ability to control insect pests in various crops.  相似文献   

4.
Characterization of new Bacillus thuringiensis strains is a valuable tool to discover novel insecticidal toxins and to manage resistance problems. In this study, seven Iranian Bt strains were selected according to their toxicity against Plodia interpunctella, to be thoroughly characterized based on their toxicity, protein profiling, proteomic analysis, gene content and β-exotoxin production. The toxicity was assessed by insect bioassays and cell viability assays (a less cost, time and material consuming technique), using four lepidopteran pests and four lepidopteran cell lines from Trichoplusia ni (Hi5), Helicoverpa zea (HzGUT), Spodoptera exigua (UCR-SE) and Spodoptera frugiperda (Sf21). The selected Bt strains showed similar protein electrophoretic profiles, but differed in toxicity. LC–MS/MS analysis of solubilized crystal proteins and gene content analyses (PCR screening) were compared and correlated with the toxicity results. Based on our data, three Bt strains could be considered as candidates for development of future bioinsecticides.  相似文献   

5.
6.
The tea red spider mite, Oligonychus coffeae Nietner (Tetranychidae), is an economically important pest of agricultural and ornamental crops and considered one of the major pests of tea plants in North-east India. In view of increasing resistance recorded in insect and mite pests against pesticides, a study was conducted to determine the acaricidal, antiovipositional, repellent and ovicidal activities of clove oil (an essential oil from the clove plant, Syzygium aromaticum L. Merr. & Perry: Myrtaceae) against tea-red-spider-mite. Mortality of O. coffeae varied with the concentrations and the duration of exposure time of the mites after application of oil. Rate of deposition of eggs by mites on treated leaf surfaces as well as the viability rate of eggs decreased significantly. In addition, certain concentrations of clove oil have been proved effective against adult mites.  相似文献   

7.
Two species of true fruit flies (taxonomic family Tephritidae) are considered pests of fruit and vegetable production in Argentina: the cosmopolitan Mediterranean fruit fly (Ceratitis capitata Wiedemann) and the new world South American fruit fly (Anastrepha fraterculus Wiedemann). The distribution of these two species in Argentina overlaps north of the capital, Buenos Aires. Regarding the control of these two pests, the varied geographical fruit producing regions in Argentina are in different fly control situations. One part is under a programme using the sterile insect technique (SIT) for the eradication of C. capitata, because A. fraterculus is not present in this area. The application of the SIT to control C. capitata north of the present line with the possibility of A. fraterculus occupying the niche left vacant by C. capitata becomes a cause of much concern. Only initial steps have been taken to investigate the genetics and biology of A. fraterculus. Consequently, only fragmentary information has been recorded in the literature regarding the use of SIT to control this species. For these reasons, the research to develop a SIT protocol to control A. fraterculus is greatly needed. In recent years, research groups have been building a network in Argentina in order to address particular aspects of the development of the SIT for Anastrepha fraterculus. The problems being addressed by these groups include improvement of artificial diets, facilitation of insect mass rearing, radiation doses and conditions for insect sterilisation, basic knowledge supporting the development of males-only strains, reduction of male maturation time to facilitate releases, identification and isolation of chemical communication signals, and a good deal of population genetic studies. This paper is the product of a concerted effort to gather all this knowledge scattered in numerous and often hard-to-access reports and papers and summarize their basic conclusions in a single publication.  相似文献   

8.
Insecticides based on crystalline toxins of Bacillus thuringiensis are very good biological plant protection products. However, the spectrum of activity of some toxins is narrow or resistance among insects has been developed. We tested the insecticidal activity of crystals of the B. thuringiensis MPU B9 strain alone and supplemented with Vip3Aa proteins against important pests: Spodoptera exigua Hübner (Lepidoptera: Noctuidae), Cydia pomonella L. (Lepidoptera: Tortricidae) and Dendrolimus pini L. (Lepidoptera: Lasiocampidae). The Cry toxins were more active for D. pini but less active against S. exigua and C. pomonella than Vip3Aa. Supplementation of Cry toxins by small amounts of vegetative insecticidal proteins demonstrated synergistic effect and significantly enhanced the toxicity of the insecticide. The results indicate the utility of Cry and Vip3Aa toxins mixtures to control populations of crops and forests insect pests.  相似文献   

9.
The increase in the production of tomato, Solanum lycopersicon Mill. (Solanaceae), has favored the proliferation of pests, especially Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). In this study, the development, reproduction, survival, and demographic parameters of T. absoluta reared on six commercial tomato cultivars (Cherry, Cordilheira, Giuliana, Nemoneta, Paron, and Santa Clara) were evaluated. Tuta absoluta completed its development in all tomato cultivars. Development from newly hatched caterpillar to newly emerged adult varied between 24.8 and 28.2 days. Female fecundity ranged from 126.3 to 166.9 eggs, with fertility from 54.2 to 84.1%. Mortality during egg-adult development varied between 21.4 and 46.4% for insects reared on cultivars Cherry and Giuliana, respectively. The cultivars Cordilheira, Giuliana, and Santa Clara are promising options to tomato producers in order to decrease the attack and proliferation of T. absoluta. However, the development and population growth of T. absoluta is faster on the tomato cultivar Cherry.  相似文献   

10.
Panonychus citri (McGregor) (Trombidiformes: Tetranychidae) is one of the main defoliator mites in citrus groves. In Brazil, P. citri was formerly considered a secondary pest, but in recent years, the population levels of this mite have increased in many groves, requiring additional acaricide applications for its control. The population growth of P. citri is associated with the increase in the number of applications of pyrethroid and neonicotinoid insecticides to control insect citrus pests. This study assessed the effects of pyrethroid (deltamethrin, esfenvalerate, λ-cyhalothrin) and neonicotinoid (imidacloprid and thiamethoxam) insecticides on biological, behavioral and demographic parameters of P. citri. None of the insecticides tested affected larval hatching, but deltamethrin, esfenvalerate, and λ-cyhalothrin reduced the survival of larvae and protonymphs. Deltamethrin, esfenvalerate, and λ-cyhalothrin induced a significant increase in the fecundity of surviving females. Pyrethroids also caused repellency and changed feeding and oviposition preferences. In contrast, imidacloprid and thiamethoxam did not affect the survival of immature stages, but imidacloprid significantly increased fecundity. Imidacloprid and thiamethoxam did not cause any repellent effect or changes in the feeding and oviposition preferences. Based on the demographic parameters, deltamethrin, λ-cyhalothrin, and imidacloprid increased Ro, r, and λ, whereas esfenvalerate and thiamethoxam were similar to the control. Therefore, the use of these insecticides (especially deltamethrin, λ-cyhalothrin, and imidacloprid) requires caution, such as avoiding repeated use of these compounds during the periods of P. citri incidence in citrus groves.  相似文献   

11.
The green peach aphid, Myzus persicae (Sulzer), is one of the most important aphid pests on pepper. Aphidius matricariae Haliday and Praon volucre (Haliday) are known as biological control agents for aphids in vegetable crops. In this research, age-specific functional responses of these two parasitoids were evaluated on different densities of 2, 4, 8, 16, 32, and 64 green peach aphids. Type of functional response varied from type II to type III for different ages of A. matricariae, but type of functional response was not affected by female age for P. volucre. The functional response of P. volucre was determined as type II in the whole parasitoid lifetime. The searching efficiency (a), b, and handling time (T h ) were estimated using the Rogers equations. The highest searching efficiency (a) and lowest handling time were observed during the first half of lifetime of A. matricariae and P. volucre. Aphidius matricariae and P. volucre caused reasonable mortality of the green peach aphid by parasitism of 52.17 and 47.05 host aphids, respectively, in 24 h. Therefore, they are suggested as suitable candidates for control of M. persicae in pepper greenhouses.  相似文献   

12.
In order to find novel strains of Bacillus thuringiensis that are toxic to some of the major pests that impact economically important crops in Argentina, we initiated a search for B. thuringiensis isolates native to Argentina. We succeeded in assembling a collection of 41 isolates, some of which show a high potential to be used in biological control programs against lepidopteran and coleopteran pests. About 90% of the strains showed toxicity against Spodoptera frugiperda and Anticarsia gemmatalis, two important lepidopteran pests in Argentina. It is noteworthy that only one of these strains contained a cry1-type gene, while another isolate showed a dual toxicity against the lepidopteran and coleopteran insects assayed. Genetic characterization of the strains suggests that the collection likely harbors novel Cry proteins that may be of potential use in biological insect pest control.  相似文献   

13.
Knowledge of the influence of both spatial and temporal environmental gradients on life history traits and population demographics is a critical requirement in the management of exploited fish populations. This study examined variation in the demographics of Arripis trutta, an economically-important pelagic fish species with a broad latitudinal distribution in the waters of coastal south-eastern (SE) Australia, a region dominated by the influence of the East Australian Current (EAC). A validated ageing protocol was first developed using sectioned sagittal otoliths, which in turn permitted examination of latitudinal variation in A. trutta growth, size compositions and age compositions. The von Bertalanffy growth function parameters for A. trutta in SE Australia were estimated to be L ?=?63.20?±?0.37 cm fork length (FL), k?=?0.26?±?0.01 yr?1 and t o?=??0.14?±?0.03 yr, with a maximum estimated age of 12.7 years. Growth was shown to be faster with decreasing latitude likely due to a simple relationship with the latitudinal gradient in water temperature; fastest growth occurring in northern NSW and slowest growth occurring in Tasmania. Latitudinal patterns in growth were remarkably similar to those previously reported for this species, despite age being estimated using scale readings some 40 years ago. This consistency in latitudinal growth patterns of a temperate fish can be attributed to the life history-related movements undertaken by A. trutta in this region. This temporally-consistent movement pattern is supported by the spatial gradient in the size and age composition of A. trutta sampled from different latitudes in both the current and historical research, whereby numbers of large and old fish increase progressively from Tasmania to northern NSW. These results highlight the need to consider the potential for spatial size- or age-structuring in the development of sampling designs and interpretation of results for any study examining spatial or temporal variation in demographic parameters of exploited fish populations.  相似文献   

14.
As soybean (Glycine max [L.] Merrill) is an important crop throughout the world, the action of herbivorous insects responsible for economic and productivity losses is the subject of constant research. Spodoptera frugiperda (J.E. Smith) caterpillars can cause extensive damage to soybean culture; this work investigated possible harmful effects on these caterpillars associated with the possible induced defenses of soybean plants. For this purpose, we assessed the biology of the insect (leaf consumption and performance traits) and chemical composition of the soybean leaves by ultraviolet–visible spectroscopy and chemometrics of three treatments: control, mechanically wounded soybean leaves, and S. frugiperda-damaged soybean leaves. The results reveal that both types of injuries induce changes in soybean metabolism regarding the production of phenolic substances, although only the herbivore-damaged plants provoke negative effects on insect biology. Variations in carotenoid production during the circadian cycle were also found in the control group. These results confirm that the soybean plants could endure and activate chemical defense mechanisms that impair the developmental lifecycle of the insect, suggesting possibilities for sustainable control strategies.  相似文献   

15.
Reducing the use of insecticides is an important issue for agriculture today. Sowing wildflower strips along field margins or within crops represents a promising tool to support natural enemy populations in agricultural landscapes and, thus, enhance conservation biological control. However, it is important to sow appropriate flower species that attract natural enemies efficiently. The presence of prey and hosts may also guide natural enemies to wildflower strips, potentially preventing them from migrating into adjacent crops. Here, we assessed how seven flower traits, along with the abundance of pollen beetles (Meligethes spp., Coleoptera: Nitidulidae) and true weevils (Ceutorhynchus spp., Coleoptera: Curculionidae), affect the density of parasitoids of these two coleopterans in wildflower strips sown in an oilseed rape field in Gembloux (Belgium). Only flower traits, not host (i.e. pollen beetles and true weevils) abundance, significantly affected the density of parasitoids. Flower colour, ultraviolet reflectance and nectar availability were the main drivers affecting parasitoids. These results demonstrate how parasitoids of oilseed rape pests react to flower cues under field conditions. Similar analyses on the pests and natural enemies of other crops are expected to help to develop perennial flower mixtures able to enhance biological control throughout a rotation system.  相似文献   

16.
The tomato leaf miner, Tuta absoluta (Meyrick), is a devastating pest of tomato worldwide. One of the control measures of T. absoluta is the use of biological control agents, such as Trichogramma wasps. Interactions between natural enemies and insect pests may be affected by application of fertilizers, because changes in plant quality through the fertilizer application may therefore affect herbivore characteristics and suitability of them to parasitism. Laboratory tests were carried out to evaluate the life table parameters of Trichogramma brassicae Bezdenko on T. absoluta eggs reared on tomato plants treated either with vermicompost (40%), humic fertilizer (2 g/kg soil), or control (suitable mixture of field soil and sand). Population growth parameters of T. brassicae were affected by fertilizer treatments. Significant differences were found for immature life period and total fecundity of T. brassicae on the treatments. Differences of intrinsic rate of natural increase (r m), finite rate of increase (λ), net reproductive rate (R 0), mean generation time (T), and doubling time (DT) of T. brassicae among treatments were also significant. The lowest values of r m, λ, and R 0 were recorded for T. brassicae developed on T. absoluta eggs on control treatment, whereas the highest values of these parameters were observed on 2 g/kg humic fertilizer. Furthermore, T. brassicae had the shortest T and DT values on 2 g/kg humic fertilizer and 40% vermicompost treatments. Our results showed that application of humic fertilizer and vermicompost could positively affect population growth parameters of T. brassicae on eggs of T. absoluta fed on tomato plants.  相似文献   

17.
The bacterial species of the genus Xenorhabdus in the family Enterobacteriaceae have a mutualistic association with steinernematid entomopathogenic nematodes (EPNs), which have been used as biological control agents against soil insect pests. In this study we present the genetic and phenotypic characterizations of the Xenorhabdus species isolated from steinernematid nematodes in Japan. The 18 Japanese Xenorhabdus isolates were classified into five bacterial species based on 16S ribosomal RNA (16S rRNA) gene sequences: Xenorhabdus bovienii, Xenorhabdus hominickii, Xenorhabdus indica, Xenorhabdus ishibashii, and Xenorhabdus japonica. There was no genetic variation between the 16S RNA sequences among the three X. ishibashii isolates, 0–0.1% variation among the five X. hominickii isolates, and 0–0.5% among the eight X. bovienii isolates. Phenotypic characterization demonstrated that representative isolates of the five bacterial species shared common characteristics of the genus Xenorhabdus, and only X. hominickii isolates produced indole. Symbiotic association and co-speciation of Xenorhabdus bacteria with Steinernema nematodes from Japan are discussed.  相似文献   

18.
The weevil Nastus fausti Reitter (Coleoptera, Curculionidae) was evaluated for its potential in the biological control of invasive giant hogweeds (Heracleum spp.). Quantitative sampling suggested that at a high population density (more that 3–4 mature larvae per plant) damage by N. fausti larvae could have some negative impact on the above-ground part of the plant. However, no-choice laboratory tests showed that N. fausti females were able to feed on a number of Apiaceae genera, including such important cultivated crops as carrot, parsnip, and celeriac. Feeding on these plants did not cause any significant decrease in female survival or fecundity. Moreover, at least part of N. fausti larvae may feed and develop on roots of these plants, and the rate of their growth and development does not differ significantly from that in larvae fed on roots of H. mantegazzianum. N. fausti adult and larval feeding on Angelica purpurascens, representative of related genus of the same tribe, was recorded under natural conditions, too. In combination, these data suggest that N. fausti is an oligophagous species connected with plants from at least several genera of Apiaceae and thus it cannot be considered a potential agent for biological control of invasive Heracleum species.  相似文献   

19.
A survey on lepidopteran pests of mangrove was conducted in different Islands of Sunderban Biosphere Reserve within the district of South 24 Parganas, West Bengal, India, over a period of 4 years (2012–2016). During the survey, a severe lepidopteran infestation was observed on the Avicennia alba Blume, which is one of the major mangrove species of Sunderbans. The life history of the lepidopteran species was studied in field as well as in laboratory conditions. The adults were identified as Hyblaea puera (Cramer, 1777) (Lepidoptera : Hyblaeidae) which is being reported for the first time from the Indian part of Sunderbans. The study revealed that the Hyblaea puera (Cramer, 1777) completed its life cycle in 21–25 days in both laboratory and field conditions. The biology and ecology of the said species and the nature of damage caused to the mangroves by these moths are discussed.  相似文献   

20.
A chimeric Bacillus thuringiensis toxin (Bt) gene, cry2AX1was cloned in a bi-selectable marker free binary vector construct. The cry2AX1 gene, driven by the Chrysanthemum rbcS1 promoter, was introduced into JK1044R, the restorer line (Oryza sativa L. ssp. Indica) of a notified commercially grown rice hybrid in India, by Agrobacterium-mediated transformation. Its effect against two major lepidopteran insect pests viz., yellow stem borer (YSB) Scirpophaga incertulas, rice leaf folder (RLF) Cnaphalocrocis medinalis and one minor insect pest, oriental army worm (OAW) Mythimna separata was demonstrated through bioassays of transgenic rice plants under laboratory and greenhouse conditions. The rbcS1 promoter with chloroplast signal peptide was used to avoid Cry2AX1 protein expression in rice seed endosperm tissue. A total of 37 independent transformants were generated, of which after preliminary molecular characterization and YSB bioassay screening, five events were selected for their protein expression and bioefficacy against all three rice insect. One elite transgenic rice line, BtE15, was identified with Cry2AX1 expression ranging from 0.68 to 1.34 µg g?1 leaf fresh weight and with 80–92 % levels of resistance against rice pests at the vegetative and reproductive stages. Increase in Cry2AX1 protein concentration was also observed with crop maturity. The Cry2AX1protein concentration in the de-husked seeds was negligible (as low as 2.7–3.6 ng g?1). These results indicate the potential application of cry2AX1 gene in rice for protection against YSB, RLF and OAW.  相似文献   

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