首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The Asian citrus psyllid, Diaphorina citri Kuwayama, vectors the causal pathogen of huanglongbing (HLB), which is likely the most important disease affecting worldwide citrus production. Interplanting citrus with guava, Psidium guajava L., was reported to reduce D. citri populations and incidence of HLB. We describe a series of investigations on the response of D. citri to citrus volatiles with and without guava leaf volatiles and to synthetic dimethyl disulphide (DMDS), in laboratory olfactometers and in the field. Volatiles from guava leaves significantly inhibited attraction of D. citri to normally attractive host‐plant (citrus) volatiles. A similar level of inhibition was recorded when synthetic DMDS was co‐released with volatiles from citrus leaves. In addition, the volatile mixture emanating from a combination of intact citrus and intact guava leaves induced a knock‐down effect on adult D. citri. Compounds similar to DMDS including dipropyl disulphide, ethyl‐1‐propyl disulphide, and diethyl disulphide did not affect the behavioural response of D. citri to attractive citrus host plant volatiles. Head‐space volatile analyses were conducted to compare sulphur volatile profiles of citrus and guava, used in our behavioural assays, with a gas chromatography‐pulsed flame photometric detector. DMDS, produced by wounded guava in our olfactometer assays, was not produced by similarly wounded citrus. The airborne concentration of DMDS that induced the behavioural effect in the 4‐choice olfactometer was 107 pg/ml. In a small plot field experiment, populations of D. citri were significantly reduced by deployment of synthetic DMDS from polyethylene vials compared with untreated control plots. Our results verify that guava leaf volatiles inhibit the response of D. citri to citrus host plant volatiles and suggest that the induced compound, DMDS, may be partially responsible for this effect. Also, we show that field deployment of DMDS reduces densities of D. citri and thus may have potential as a novel control strategy.  相似文献   

2.
[目的] 明确佛冈县不同类型橘园柑橘木虱的种群动态,为当地柑橘木虱及柑橘黄龙病的防治工作提供科学依据。[方法] 通过2015-2016年的系统调查,对广东省佛冈县砂糖橘园的柑橘木虱种群消长动态进行研究,对比分析了不同处理措施对柑橘木虱种群数量的影响。[结果] 1-3月柑橘木虱发生危害较轻,随着嫩梢增多,其种群数量开始上升,6-9月为种群发生高峰期,期间出现多个发生高峰,10月之后种群数量逐渐进入消退期,种群数量维持在较低水平;2015、2016年佛冈县柑橘木虱的季节性消长动态基本一致,但种群发生量存在明显差别;3种不同类型橘园内柑橘木虱种群发生数量也存在显著差异,常年失管橘园柑橘木虱种群发生数量最高,常规水肥管理橘园次之,二者均显著高于常规水肥管理及化学防治橘园。[结论] 化学防治可在一定程度上控制柑橘木虱的种群数量,及时清理失管橘园对控制柑橘木虱和柑橘黄龙病传播至关重要。  相似文献   

3.
Summary For the first time the Authors have proved in the laboratory and in the fieldB. thuringiensis against the citrus-flower moth (Prays citri Mill.) successfully.

La memoria originale è stata publicata per esteso nelBollettino dell'Istituto di Entomologia Agraria e dell'Osservatorio di Fitopatologia di Palermo, 6.  相似文献   

4.
İsmail Kasap 《BioControl》2011,56(3):327-332
This study examined the efficacy of the predatory mite Typhlodromus athiasae Porath and Swirski (Acari: Phytoseiidae) as a biological control agent of the citrus red mite Panonychus citri (McGregor) (Acari: Tetranychidae) on seedlings of Washington and Valencia citrus cultivars at 1:10, 1:20 and 1:40 predator:prey release ratios under greenhouse conditions. At predator:prey ratios of 1:10, significant reductions on P. citri populations were observed one week after release of T. athiasae, and populations remained at low levels thereafter. The highest mean numbers of P. citri were found in the third week on the Washington cultivar and in the fourth week on Valencia, in a control group with no predators. This study demonstrates the potential of T. athiasae to effectively control P. citri on Washington and Valencia cultivars under greenhouse conditions at predator:prey ratios of 1:10. However, T. athiasae was unable to control the citrus red mite populations when the predator:prey ratio was reduced to 1:40. We therefore recommend a release ratio of 1:10 for effective control of P. citri in greenhouses on seedlings of Washington and Valencia citrus.  相似文献   

5.
The parasitoid Encarsialahorensis has been present in Israel since its import in 1980 for biological control of Dialeurodes citri, a serious pest of citrus. The larvae of D. citri secrete honey dew, which is colonized by sooty mould fungi, leading to aesthetic impairment of the fruit as well as leaf drop and yield loss. In a process which took about 3years, the parasitoid reduced the pest to low levels and maintained the population beneath the economic damage threshold for several years. This study, carried out in a citrus orchard during the years1987–1991, was intended to demonstrate the existence of efficient biological control by comparing the pest populations before and after the unhindered introduction of the natural enemy to a new region. In the course of two years, the pest population decreased from a peak level of 122 eggs to 2–7 per half-leaf. Concurrently, the population of the vulnerable fourth nymphal in star decreased from a maximum of 12 to 3 perhalf-leaf. Thereafter, D. citri was maintained at this low level, with peaks of parasitism ranging from20 to 50%. It was concluded that D. citri is under successful biological control in Israel by the specific parasitoid E. lahorensis. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

6.
Planococcus citri (Risso) is one of the major pests of citrus orchards in India. For the control ofP. citri, an encyrtid parasite,Leptomastix dactylopii How. was introduced from West Indies in 1983. The parasite was mass bred and inoculative releases were made in 2 selected citrus orchards where infestation of mealybug on fruits (sweet orange, seedless lime and acid lime) ranged from 38 to 65 per cent. Establishment of the parasite in the 2 release orchards resulted in complete control of the mealybug within 3 to 4 months. No insecticidal sprays were required subsequently for the control ofP. citri in the following seasons. Contribution No. 152/85 of the IIHR, Bangalore — 560089.  相似文献   

7.
The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a major citrus pest that transmits the bacteria Candidatus Liberibacter asiaticus and Ca. L. americanus associated with huanglongbing (HLB) disease. Diaphorina citri population densities can affect the effectiveness of its monitoring and sampling methods. Thus, we compared different methods for adult D. citri monitoring in groves with and without insecticide application programmes. Four short‐term experiments were carried out, each one lasting four consecutive weeks. In these experiments, sticky cards with different colours (yellow, light green, green and dark green), sweep net, two suction device models, visual inspection and stem tap sampling were assessed. Two long‐term experiments were conducted for 4.5 and 5 years, in which only yellow sticky card and visual inspection for D. citri monitoring were assessed. For the short‐term experiments, psyllids were detected by all monitoring methods during all sampling periods in areas without chemical control. However, in areas with psyllid control via fortnightly and monthly applications of insecticides, only sticky cards, regardless of their colour, were able to detect the presence of D. citri. Similarly, for the long‐term experiments, yellow sticky cards were more effective than visual inspection for detecting and quantifying D. citri in all areas with or without insecticide application. Therefore, in areas where HLB is present and chemical control of psyllid is required, sticky cards are the most reliable option for monitoring D. citri.  相似文献   

8.
We investigated how chemical cues derived from female Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) and their host plants affect host acceptance choices by conspecifics. In four-choice cage and two-choice olfactometer assays, female psyllids avoided conspecific female cues in a density-dependent manner. However, odors from citrus plants actively damaged by psyllid feeding were attractive to conspecific females. When odors from feeding-damaged plants were presented simultaneously with odors from female D. citri, attraction of female conspecifics was no longer observed as compared with a clean air control in olfactometer assays. In subsequent experiments, D. citri females were released within arenas that contained actively feeding-damaged or non-damaged (control) citrus plants, each with previously psyllid-infested and uninfested young leaves. D. citri development is linked to the presence of these newly emerging leaves which is the only site of nymphal development. Female D. citri were initially attracted by the actively damaged plants as compared with non-damaged controls. After acceptance of plants that were actively damaged by feeding, D. citri females preferentially chose and settled on uninfested young leaves as compared with previously infested young leaves. A herbivore-induced plant volatile attractant and a female-specific odor repellent appear to be complementary foraging cues providing psyllids with information at two spatial scales: (1) the whole plant level for choosing a plant potentially harboring male conspecifics for mating, and (2) the within plant level to reduce intra-conspecific competition by identifying previously exploited resources.  相似文献   

9.
In the present study, we determined the critical stages and the key factors of mortality for Planococcus citri (Hemiptera: Pseudococcidae) in Brazilian coffee plantations using a life table to understand the role of natural biological control on its population. Predators, parasitoids, rainfall, sunlight, physiological disturbances and fungal diseases were collectively responsible for 98.79% in the total mortality of P. citri. Predators belonging to the Chrysopidae, Syrphidae, Dolichopodidae and Coccinellidae families were the most important mortality factors in the early developmental stages of P. citri (i.e. eggs and 1st and 2nd instar nymphs), whereas predators belonging to the Coccinellidae and Chrysopidae families were the most important mortality factors for the last instars (i.e. 3rd instars and adults) for P. citri. The generalist predators Harmonia axyridis, Chrysoperla genanigra and Chrysoperla externa were the key mortality factors for P. citri. The third nymph stage was considered the critical life stage (i.e. the life stage that most influences population size). Our results show that generalist predators and climatic factors are important sources of natural mortality of P. citri governing the population dynamics of this pest in the field.  相似文献   

10.
Huanglongbing (HLB) is the most destructive disease of citrus worldwide. The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is the vector of the phloem‐inhabiting bacterium, Candidatus Liberibacter asiaticus, which is presumed to cause HLB in Florida citrus. Laboratory and field studies were conducted to examine the behavioral responses of male and female D. citri to their cuticular extracts. In olfactometer assays, more male D. citri were attracted to one, five, or 10 female cuticular extract equivalent units than blank controls. The results were confirmed in field studies in which clear or yellow traps baited with 10 female cuticular extract equivalent units attracted proportionately more males than clear traps baited with male cuticular extract or unbaited traps. Analyses of cuticular constituents of male and female D. citri revealed differences between the sexes in chemical composition of their cuticular extracts. Laboratory bioassays with synthetic chemicals identified from cuticular extracts indicated that dodecanoic acid attracted more males than clean air. Traps baited with dodecanoic acid did not increase total catch of D. citri as compared with blank traps at the dosages tested; however, the sex ratio of psyllid catch was male biased on traps baited with the highest lure loading dosage tested (10.0 mg).  相似文献   

11.
1. The response of a phytopathogen vector to pathogen‐induced plant volatiles was investigated, as well as the response of the phytopathogen vector's parasitoid to herbivore‐induced plant volatiles released from plants with and without drought stress. 2. These experiments were performed with Asian citrus psyllid (Diaphorina citri), vector of the plant pathogen Candidatus Liberibacter asiaticus (CLas) and its parasitoid Tamarixia radiata as models. Candidatus Liberibacter asiaticus is the presumed causal pathogen of huanglongbing (HLB), also called citrus greening disease. 3. Diaphorina citri vectors were attracted to headspace volatiles of CLas‐infected citrus plants at 95% of their water‐holding capacity (WHC); such attraction to infected plants was much lower under drought stress. Attraction of the vector to infected and non‐stressed plants was correlated with greater release of methyl salicylate (MeSA) as compared with uninfected and non‐stressed control citrus plants. Drought stress decreased MeSA release from CLas‐infected plants as compared with non‐stressed and infected plants. 4. Similarly, T. radiata was attracted to headspace volatiles released from D. citri‐infested citrus plants at 95% of their WHC. However, wasps did not show preference between headspace volatiles of psyllid‐infested and uninfested plants when they were at 35% WHC, suggesting that herbivore‐induced defences did not activate to recruit this natural enemy under drought stress. 5. Our results demonstrate that herbivore‐ and pathogen‐induced responses are environmentally dependent and do not occur systematically following damage. Drought stress affected both pathogen‐ and herbivore‐induced plant volatile release, resulting in concomitant decreases in behavioural response of both the pathogen's vector and the vector's primary parasitoid.  相似文献   

12.
Tamarixia radiata Waterston (Hymenoptera: Eulophidae) is an effective idiobiont ectoparasitoid of the psyllid Diaphorina citri Kuwayama (Hemiptera: Psyllidae), vector of the huanglongbing (HLB). We examined the olfactory responses of T. radiata to volatiles emanating from D. citri or plant volatiles using a custom designed T-maze olfactometer and open arena bioassays. We also examined the behavioral response of male and female T. radiata to conspecifics of the opposite sex to determine whether olfactory signals mediate mate location. T. radiata adults exhibited a sexually dimorphic response to volatiles emanating from D. citri and citrus. Female T. radiata responded positively to the odors emanating from D. citri nymphs in both olfactometer and open arena bioassays. However, female wasps showed no response to odors emanating from D. citri adults, D. citri honey dew secretions, intact citrus or orange jasmine leaves. Odors emanating from D. citri damaged citrus were not attractive to T. radiata females but stimulated attraction of wasps to D. citri on damaged plants. T. radiata females were not attracted to D. citri immatures when they were presented as visual cues. Male T. radiata did not show attraction to D. citri nymphs or other putative odors that were attractive to female T. radiata. In olfactometer bioassays, more male T. radiata responded to the odor of female conspecifics than blank controls in the absence of associated citrus host plant volatiles. Odors emanating from female T. radiata were not attractive to male T. radiata. Male or female T. radiata were not attracted to the odors emanating from same sex conspecifics. Both male and female T. radiata adults showed positive phototactic behavior. Collectively, our results provide behavioral evidence that: 1) female T. radiata use volatiles emanating from D. citri nymphs to locate its host and: 2) female T. radiata release a volatile pheromone that attracts male conspecifics.  相似文献   

13.
Studies designed to measure dispersal capacity of Diaphorina citri Kuwayama (Hemiptera: Liviidae) are needed to provide the epidemiological knowledge necessary to improve management of citrus huanglongbing. In this study, a mark–release–recapture technique was used to investigate whether 1) host or non‐host plants of D. citri can act as barriers for dispersing insects and 2) presence or absence of young citrus leaves influence movement of D. citri towards citrus plants. The experimental field consisted of four circular and adjacent areas containing citrus trees, Citrus sinensis (L.) Osbeck cv. ‘Hamlin’, planted in concentric circles at 18, 24 and 30 m from the release centre. Insect activity was monitored by recapturing at each distance using yellow stick traps. Dense plantings of tall non‐host plants of D. citri such as corn had no effect on insect dispersal towards citrus plants when compared to a shorter cover crop such as grass. In contrast, suitable host plants acted as traps decreasing movement of D. citri. Diaphorina citri dispersed at greater speeds in the absence of young leaves reaching 140 m within 6 hours after release, whereas in the presence of young leaves, individuals reached at most 60 m at 1 day after release. Results suggest that D. citri control measures may be more efficient during periods of highest vegetative activity when insects are less active. Moreover, the use of suitable host plants for D. citri as trap plants may be a potential tactic to prevent movement of insects into the crop.  相似文献   

14.
Summary Pattern of population growth and characteristics of habitat utilization and of migration by two species of spider mites were studied under experimental conditions. The population growth ofOligonychus ununguis (Jacobi) on a chestnut occurred only on a single mite-release leaf over a long period, and few individuals moved away. Most of the 2nd progeny generation females of this species emigrated from the mite-release leaf as well as the sapling by means of ballooning threads. During this growth period, population density on the mite-release leaf levelled off, whereas that on the sapling increased. In contrast, the foundress ofPanonychus citri (McGregor) on citrus actively moved over several neighbouring leaves, and until the 2nd progeny generation females emerged, individuals were distributed over all the sapling leaves by means of walking. Emigration from the sapling was not observed until the 2nd progeny females emerged, and after that the mites emigrated by means of ballooning threads. The population density ofP. citri on the sapling levelled off and was rather decreased on the mite-release leaf at the time of mite emigration. Comparing the changing pattern of the relative degree of aggregation (m */m) measured in two different units between these two species, the pattern ofm */m in 1 cm2 on the mite release leaf inO. ununguis resembled that of the unit of leaves on the sapling inP. citri. This result as well as behavioural observations indicate that migration ofO. ununguis is the movement from leaf to leaf and that ofP. citri from sapling to sapling. It is, therefore, concluded that the boundary of the microhabitat is a single leaf forO. ununguis but sapling or foliage forP. citri. This work was presented in Annual Meeting of Jap. Soc. Appl. Ent. Zool., 1981 in Okayama.  相似文献   

15.
16.
Crops in the Family Malvaceae are attacked by various insect pests especially Podagria species (Coleoptera: Chrysomelidae) at different stages of their development. The emergence of biodegradable pesticides (botanicals) as safe option has reduced the problems that result from the use of synthetic insecticides, thus creating a renewed interest in their development and use in integrated pest management of crops. Therefore, field experiments were conducted to investigate the control capability of water extracts of Piper guineense seeds and Cypermethrin on flea beetles (Podagrica spp.) infesting okra (Abelmoschus esculentus (L.) Moench). The experiments were conducted in two locations in the rain forest zone of Nigeria. The first experiment was conducted at the Teaching and Research Farm of The Federal University of Technology Akure, Ondo State (2011 Early cropping season), while the second experiment was carried out at the Teaching and Research Farm of Rufus Giwa Polytechnic, Owo, Ondo State (2011 Late cropping season). A synthetic insecticide (Cypermethrin) was included in the treatments as a standard check alongside the untreated (control). The experimental design was laid out in a randomised complete block design with five treatments replicated three times. The effectiveness of the treatments was determined based on reduction in the population of the adult insects. The results showed that water extract of P. guineense seeds and the synthetic insecticide significantly (p?<?0.05) reduced the population of the flea beetles as compared with the control. The synthetic insecticide-treated plots produced the highest standard check, but this was not significantly different from the dried yield recorded in the plots sprayed with aqueous extracts of P. guineense seeds. The results of field trials in both cropping seasons showed that all the treatments significantly suppressed the infestation by the flea beetles throughout the study period. In view of the ability of water extract of P. guineense seeds to control the infestation of Podagrica spp. its use by farmers is therefore recommended.  相似文献   

17.
The Asian citrus psyllid, Diaphorina citri Kuwayama, a vector of citrus huanglongbing, is now present in all citrus‐producing states in the USA and Mexico. In addition to citrus, the insect can reproduce on several other plant species in the Rutaceae family; orange jasmine (Murraya spp.) and curry leaf (Bergera koenigii) are among its preferred hosts. There are several indigenous Rutaceae species in North America, and some are popular ornamentals. A study was therefore initiated to determine the suitability of some of these plants for feeding and development of the psyllid in choice and no‐choice experiments. D. citri was found to reproduce successfully on Choisya ternata, C. arizonica and Helietta parvifolia in no‐choice tests, but preferentially selected orange jasmine and curry leaf for feeding and reproduction, in choice tests. On Amyris madrensis, A. texana and Zanthoxylum fagara, adult psyllids laid eggs which hatched, but no successful nymphal development was recorded beyond the first instars. No oviposition was recorded on Esenbeckia berlandieri, Ptelea trifoliata and Casimiroa tetrameria, although adult psyllids were able to survive on these species for several days. Results showed that C. ternata, C. arizonica and H. parvifolia can serve host plants of D. citri and this constitutes the first report of these plants serving as host for D. citri. The findings of the present study suggest that native rutaceous host plants can serve as host plants and thus affect D. citri population dynamics and the epidemiology of Huanglongbing, the deadly citrus greening disease whose pathogen is vectored by D. citri. Thus, area‐wide management of this pest also should target these riparian habitats where these host plants are present with D. citri biological control agents for sustainable management of this pest.  相似文献   

18.
We determined the effect of ground cover on phytoseiid predatory mite populations and the potential biological control of Panonychus citri (McGregor). Results showed that citrus trees with ground cover contained higher population densities of predatory mites and provided better regulation of P. citri than trees in bare soil. The ground cover Ageratum conyzoides L. performed better than Palspalum notatum Flugge in sheltering phytoseiid mites.  相似文献   

19.
Considering the fact that Prays oleae is one of the most pathogenic insects to the olive tree in the Mediterranean particularly in Tunisia, the mode of action of Cry insecticidal toxins of Bacillus thuringiensis kurstaki in Prays oleae midgut was investigated. The proteolysis of Bacillus thuringiensis δ-endotoxins in the midgut was a key step in determining their potency against Prays oleae. The latter's proteases activated the δ-endotoxins early, yielding stable toxins. The in vitro and in vivo binding of these toxins to Prays oleae larvae midgut was studied immunohistochemically, evidencing a midgut columnar cell vacuolization, microvilli damage, and then a pass of epithelium cell content into the larvae midgut. Moreover, Bacillus thuringiensis toxins were shown to bind to the apical microvilli of the midgut epithelial cells. The in vitro study of the interaction of Prays oleae midgut proteins with biotinylated Bacillus thuringiensis toxins allowed the prediction of four suitable receptor proteins in Prays oleae.  相似文献   

20.
The Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) is an insect vector that transmits the bacterial pathogen Candidatus Liberibacter asiaticus (CLas) associated with the destructive citrus disease, citrus huanglongbing (HLB). Currently, D. citri is the major target in HLB management, although insecticidal control and disruption of the D. citri–CLas interactions both face numerous challenges. The present study reports the subcellular proteomic profiles of D. citri, encompassing the three main subcellular protein fractions: cytosol, mitochondria and microsomes. After optimization, subcellular proteins of both high and low abundance are obtained by two‐dimensional gel electrophoresis (2‐DE). A total of 1170 spots are detected in the 2‐DE gels of the three subcellular fractions. One hundred and sixty‐four differentially expressed proteins are successfully identified using liquid chromatography‐dual mass spectroscopy. An efficient protocol for subcellular protein fractionation from D. citri is established and a clear protein separation is achieved with the chosen protein fractionation protocol. The identified cytosolic proteins are mainly metabolic enzymes, whereas a large portion of the identified proteins in the mitochondrial and microsomal fractions are involved in ATP biosynthesis and protein metabolism, respectively. Protein–protein interaction networks are predicted for some identified proteins known to be implicated in pathogen–vector interactions, such as actin, tubulin and ATP synthase, as well as insecticide resistance, such as the cytochrome P450 superfamily. The findings should provide useful information to help identify the mechanism responsible for the CLas–D. citri interactions and eventually contribute to D. citri control.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号