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1.
Antifeeding and toxic effects of chemical extracts from Porteresia coarctata Takeoka on the insect pest Spodoptera litura (F.) were investigated in the laboratory. Hexane extracts of P. coarctata leaves were re-dissolved in dimethyl sulfoxide and applied in water to leaves of Ricinus communis L. (castor). A concentration of 1,000 and 2,000 ppm extract exhibited significant antifeeding and toxic effects to third instar larvae when compared to the same concentration of dimethyl sulfoxide in water as control. One day after feeding on extract-treated castor leaves, the mortality of S. litura larvae was 50%. Mortality increased to 95% after 11 days at a dosage of 2,000 ppm. Compared to the control, third instar larvae fed on castor leaves treated with P. coarctata leaf extract at different concentrations showed significant reduction in protein and DNA content in the fat body and midgut tissues. Results demonstrate the insecticidal and antifeedant properties of P. coarctata leaf extract against the generalist pest S. litura leading to biochemical changes in the insect body. Thus, P. coarctata contains phytochemicals, and the extract, in crude and pure form, has potential as a botanical insecticide in alternative control strategies against Lepidoptera pests.  相似文献   

2.
The ethanol extracts obtained from both leaf and seed in the Thorn apple (Datura stramonium L.) (Solanaceae) were investigated for acaricidal, repellent and oviposition deterrent properties against adult two-spotted spider mites (Tetranychus urticae Koch) (Acari: Tetranychidae) under laboratory conditions. Leaf and seed extracts, which were applied in 167,250 and 145,750 mg/l concentrations, respectively (using a Petri leaf disc-spray tower method), caused 98 and 25% mortality among spider mite adults after 48 h. The simple logistic regression analysis showed that the independent variable, an increase in the dose of leaf extract was associated with a significant increase in the death rate of T. urticae females, but an increase in the dosage of seed extracts did not have a significant effect. Using probit analysis and estimating the parameters with a confidence limit of 95%, we determined the LC50 values of leaf extract to be 70,593 mg/l. According to Pearson’s χ2 test, mites showed the strongest run off to bean leaf surfaces sprayed with both leaf and seed extracts (in sub-lethal doses: <7,500 mg/l and <25,000 mg/l, respectively) and moved towards surfaces that had not been sprayed with extracts. Furthermore, repeated measures ANOVA indicated a significant difference between the number of eggs laid on unsprayed bean leaves compared to bean leaves that were sprayed with leaf and seed extracts at sub-lethal doses, 2,500 and 25,000 mg/l concentrations, respectively. These results suggest that D. stramonium extracts could be used to manage the two-spotted spider mite.  相似文献   

3.
Several species of the large family of tropical plants Annonaceae have been intensely investigated over the last 20 years, mainly because of the discovery of annonaceous acetogenins. These compounds are powerful cytotoxics, with potential applications as insecticides, antiparasitics, acaricides, fungicides, and antitumor drugs. Annona montana Macfad. (Annonaceae) grows in Santa Cruz de la Sierra, Bolivia, where an infusion of leaves is used for the treatment of lice, influenza, and insomnia. The major acetogenins from a Bolivian collection of A. montana, annonacin (1), cis-annonacin-10-one (2), densicomacin-1 (3), gigantetronenin (4), murihexocin-B (5), and tucupentol (6), were evaluated for their antifeedant and toxic effects on Spodoptera frugiperda Smith (Lepidoptera: Noctuidae), a serious pest affecting corn crops in Argentina. All the acetogenins produced 100% mortality during the larval or pupal stages at 100 μg of treatment per gram of diet. In addition, compounds 2, 3, and 4 deterred more than 80% feeding at the same dose. Relative toxicity values of LD50 for the strongest larvicidal compounds 1, 2, and 4 were determined, indicating that the three compounds are effective natural insecticides. This is the first report on the antifeedant and toxic effects produced by the particular type of acetogenins, the mono-THF acetogenins, on the lepidopteran S. frugiperda. No correlation was detected between the toxicity of the mentioned compounds to larvae and the known capacity of the acetogenins 1, 2, and 4 to inhibit the NADH oxidase, indicating that the inhibition of the mitochondrial complex I is not the only cause for larval mortality of S. frugiperda.  相似文献   

4.
Citrus mealybug Planococcus citri (Risso) (Hemiptera: Pseudococcidae) is one of the main pests on citrus trees. Biological control of the pest is based on the release of hymenopterous parasitoids and coccinellid predators at present. The effectiveness of entomopathogen fungus Isaria farinosa (Holmsk.) Fries ([Sordariomycetes: Hypocreales] (Syn: Paecilomyces farinosus), as an alternative biological control agent on citrus mealybug, was investigated using four different inoculum densities and different relative humidities (RH). The entomopathogen caused 89.39% mortality in ovisacs, 84.07% mortality in second larval stage, 84.53% mortality in adult females, and 78.71% mortality in first larval stage at 95% RH and at 1 × 108 conidia ml−1 inoculum concentration. Percent mortalities were between 50 and 60 in ovisac, first and second larval stage at 95% RH and at 1 × 107 conidia ml−1. Percent mortality was decreased parallel to the decrease in humidity level and inoculum densities; however, the fungus caused significant infection in 70% and 80% RH. These results demonstrated that the effectiveness of the entomopathogen is promising for biocontrol of citrus mealybug.  相似文献   

5.
Poplar leaf defoliator, Clostera fulgurita (Walker) larvae were reared on three Populus deltoides clones (PL1, PL5 and PL7) in the laboratory. The nutritional indices were computed for working out the relationship between food consumption and growth rate of 3rd, 4th and 5th instar larvae on three clones. The result showed that the consumption index (CI), approximate digestibility (AD), growth rate (GR), relative growth rate (RGR) and efficiency of conversion of ingested food (ECI) decreased with the increase in the age of the larvae. Efficiency of conversion of digested food (ECD) increased with increase in age of the larvae. GR and RGR varied significantly, indicating that larval development was enhanced on PL1 as compared to PL5 & PL7. The values of AD, ECI and ECD were not affected by the different clones. Feeding and growth indices could be useful to define a defoliation prediction model.  相似文献   

6.
In a laboratory screening of 12 isolates of entomopathogenic fungi against nymphs of the mulberry whitefly (Pealius mori Takahashi), Beauveria bassiana (Balsamo-Crivelli) Vuillemin CKB-048 was the most virulent, causing 87 ± 3% mortality at 1 × 106 conidia/ml. Infection was confirmed by growth of the fungus from cadavers and by scanning electron microscopy of treated nymphs. Beauveria bassiana CKB-048 was formulated as a wettable powder (1 × 109 conidia/g) and tested in two mulberry (Morus alba Linn) plantations in central and northeastern Thailand. In both locations, two spray applications of B. bassiana CKB-048 at 3.75 × 1012 to 6.25 × 1012 conidia/ha and at 14 day intervals provided good control of whitefly nymphs; control with B. bassiana CKB-048 was comparable to that with the pesticide buprofezin at 250 g of active ingredient/ha. In addition, no mortality of silkworm larvae occurred when the larvae were fed with mulberry leaves sprayed with B. bassiana CKB-048 7, 14, or 21 days earlier.  相似文献   

7.
The success of tree plantings in agricultural landscapes within dry and variable rainfall regions is often below expectations. The aims of this study were to investigate techniques for establishing a local native species (Eucalyptus pauciflora) and an exotic species (E. nitens) in the Midlands of Tasmania, a tree-denuded region that has been grazed for over 100 years in Australia. We established trials at the Sorrel Springs and Woodland Park properties. We compared six establishment techniques: control; understorey nurse planting; spot burn; mulch; tree-guard and; self-watering tree-guard. Three months, 1 and 6 years after planting we measured tree height, health index and mortality. At Sorrell Springs tree-guarded treatments had greater height than other treatments at year one, but there were no effects of treatment at year six on height, health or mortality. At Woodland Park mulch, burn and tree-guarded treatments had greater height 1 and 6 years after planting. At year six tree-guarded treatments had lower mortality than other treatments. At Sorrell Springs height of E. nitens was greater than E. pauciflora at year one but not at year six. At Woodland Park height of E. nitens was generally greater at year six but having almost double the incidence of mortality relative to E. pauciflora. We conclude that expensive tree-guarding is only warranted where high browse pressure is expected and that on such sites species with tough leaves that are resistant to browsing should be considered. Further that in environments marginal for growing trees, best practice establishment technique is generally as effective as additional treatments of understorey nurse planting, spot burning or mulching.  相似文献   

8.
The biological activity of essential oil extracted from coriander, Coriandrum sativum L. (Apiaceae) against eggs, larvae and adults of Tribolium castaneum (Herbst) was investigated in a series of laboratory experiments. Bioassays conducted in air-tight glass chambers showed vapour toxicity and strong repellency on filter paper arena test towards all the stages used. Responses varied significantly (P < 0.001) within insect stages, dosages and exposures. At 12.0 μg/ml dosage, mortality of adults reached 95%, but for 12-, 14- and 16-days larvae, mortalities were 65, 74 and 82%, respectively. On the developmental inhibition, individuals fumigated at the larval stage confirmed that the percentage of larvae reaching to pupal stage and pupae to adult stage, decreased significantly (P < 0.001) with increasing dosage concentration. The oil fumigation yielded 100% mortality for T. castaneum larvae, pupae and adults at 0.08 μg/ml dosage. The oil had fumigant activity against eggs and the toxicity progressively increased with increased exposure times and concentrations. One hundred per cent T. castaneum egg mortalities were obtained with oil fumigation at 20 μg/ml and 96 h exposure period. C. sativum oil also showed highly repellent activity to the adults of T. castaneum, with overall repellency was 90% and at a dosage of 12 μg/ml repellency was 100% in a filter-paper arena test.  相似文献   

9.
In order to determine their effects on growth and mortality of instar II Hypsipyla grandella (Zeller), larvae were fed with leaf disks taken from shoots of susceptible species (Cedrela odorata L. and Swietenia macrophylla King) scions grafted onto resistant ones (Khaya senegalensis Desr. A. Juss and Toona ciliata M. Roem.), from their reciprocal grafts, and from both intact and autografted plants. In addition, crude leaf extracts from the susceptible and resistant plants, as well as from C. odorata grafted onto T. ciliata plants, were tested on C. odorata leaf disks. Mortality was evaluated 2, 10, and 25 days after starting the bioassay. Leaf area consumed and weight gain per larva were assessed 2 days after starting bioassay. Time to reach pupation, pupal weight and length 1 day after pupation, and time to adult stage and appearance of wings were determined at the end of the bioassay. Plant species significantly affected mortality (P ≤ 0.04) throughout the test. Eighty to 100% of larvae fed leaf disks from intact T. ciliata and its autograft, or C. odorata onto T. ciliata and its reciprocal graft died in the first 2 days of evaluation. All other factors measured, except pupal weight and length, were also affected (P ≤ 0.01) by the leaf disks. Intact resistant plants and reciprocal grafted plants reduced leaf consumption and caused larval weight loss. Larvae fed on K. senegalensis grafted onto S. macrophylla extended by 8 days the time to pupa and to adult stages and induced abnormal wing formation compared to larvae fed intact leaves of C. odorata. Crude extracts from resistant plants equally affected larval survival and performance compared to crude extract from C. odorata grafted onto T. ciliata plants, and these extracts were more detrimental to larvae than those from susceptible species. This study demonstrated that grafting borer-susceptible species on resistant rootstocks can affect the survival and performance of instar II H. grandella larvae.  相似文献   

10.
In honeybee, Apis mellifera, colonies infested with larval and adult small hive beetles (SHB), hive material, and in particular honey, tends to ferment, probably due to SHB-associated yeasts such as the predominant Kodamaea ohmeri. Here, we test the effects of organic acids on K. ohmeri and on SHB-infested honey/pollen combs. Organic acids were applied at standard concentrations used by beekeepers to control other pests. In laboratory tests, the growth of K. ohmeri was significantly inhibited by lactic, formic and acetic acids. Treatments of SHB-infested honey/pollen combs (N = 18 colonies) with acetic acid significantly increased mortality of adult SHB and treatments with formic acid significantly reduced larval infestation. Our data suggest that treatment of honeybee colonies and storage rooms with organic acids could also help in reducing SHB damage.  相似文献   

11.
Several authors record high mortality of the weedy species Rumex obtusifolius in unmanaged grasslands, but there have never been any studies on how the performance and mortality of R. obtusifolius and R. crispus are affected by different nutrient availability in unmanaged temperate grasslands. To investigate this question, we established a seedlings transplantation and fertiliser experiment on unmanaged Dactylis glomerata grassland in Czech Republic. We monitored plant height, number of leaves per plant, fertility and mortality of transplanted R. obtusifolius and R. crispus plants, from 2008 to 2011, in an unfertilised (U) and a fertilised (F) treatment (manure applied in 2008 at the rate of 200 kg of nitrogen, 42 kg of phosphorus and 230 kg of potassium per ha). In 2010, taller plants of both species were recorded in treatment F than in treatment U, but there was no effect of treatment on the number of leaves. In 2010, fertility for both species was 50% in treatment F, but only 20% for R. obtusifolius and 10% for R. crispus in treatment U. Over 4 years, no mortality of R. obtusifolius in treatment F contrasted with 30% mortality in treatment U. In the case of R. crispus, mortality was 50% in treatment F and 28% in treatment U. An increase in nutrient availability can decrease mortality of R. obtusifolius plants in grasslands, but increase mortality of R. crispus. It seems that leaving grassland unmanaged for several years is only an effective strategy for control of R. obtusifolius under conditions of low nutrient availability.  相似文献   

12.
Flavonoids function in many aspects of plant–insect interactions, but the responses of insects to these compounds vary greatly. In this study, we determined the effects of two widely distributed flavonoids, pinocembrin and quercetin, on the feeding behavior, survival, and development of the fall armyworm Spodoptera frugiperda J.E. (Smith) (Lepidoptera: Noctuidae). In a choice test, S. frugiperda larvae strongly rejected leaves treated with pinocembrin at concentrations of 10, 50, or 100 μg/cm2. Larvae fed normally on leaves treated with quercetin at 10 and 50 μg/cm2, but showed 57 % deterrence when fed on leaves treated with 100 μg/cm2 quercetin. At concentrations of 0.01–1 µg/cm2, pinocembrin and quercetin functioned as phagostimulants for S. frugiperda. In a multiple-choice experiment, S. frugiperda larvae preferred to consume untreated leaves or those treated with 0.1 µg/cm2 pinocembrin, but rejected leaves treated with 5–50 µg/cm2 pinocembrin. In a no-choice feeding experiment, larvae fed on leaves treated with 5 and 50 μg/cm2 pinocembrin consumed less than those fed on leaves treated with 0.1 and 1 μg/cm2 pinocembrin or untreated leaves. Pinocembrin at 1–50 μg/cm2 negatively affected larval weight and survival, thus showing a toxic effect. In contrast, leaf consumption and larval weight were not significantly affected by quercetin at 0.1, 1, 5, and 50 μg/cm2, and mortality rates only slightly increased. Because of its dual activity, pinocembrin could be used for insect control in a stimulo-deterrent diversionary strategy: the same compound could promote both stimulate (low doses) and deter insect activity (high doses).  相似文献   

13.
Sugar beet, Beta vulgaris L. is a strategic crop of sugar industry in Egypt. It is threatened by several insect pests among most important of them is the beet beetle Cassida vittata. This work deals with the biological control of this insect using four Egyptian and imported entomopathogenic nematodes (EPNs). The nematodes included Steinernema carpocapsae S2, Heterorhabditis bacteriophora S1, S. feltiae and H. bacteriophora (1-3). Daily mortality of larvae, pupae and adults of C. vittata were recorded after treatment with serial concentrations (from 500 to 4,000 infective juveniles/ml) of each of four studied EPNs. Development of nematodes in insect bodies was followed up. S. carpocapsae S2 was chosen for the application against different stages of the pest in a sugar beet field. In the field, single application of S. carpocapsae S2 killed 65% of the larvae, 92% of the pupae and 57.3% of the adults of C. vittata within a week. This work is the first report on using the EPNs to control sugar beet beetle.  相似文献   

14.
This study estimates the efficacy of an attract-and-kill (A&K) technique to control the horse chestnut leaf miner, Cameraria ohridella Deschka and Dimic (Lepidoptera, Gracillariidae), an invasive insect pest of the horse chestnut, Aesculus hippocastanum L. (Hippocastanaceae). The A&K formulation was dispensed as 50 μl droplets of paste-like matrix, containing C. ohridella sex pheromone, (8E,10Z)-tetradeca-8,10-dienal (85% + pure; 0.16% w/w) and a fast acting contact toxicant, pyrocides (94% pure; 6% w/w), applied directly to the bark of the trees. It was tested in 2003 at rates of 30 and 45 droplets/tree at the Ostrobramska site and at rates of 30, 60 and 90 droplets/tree at the Woloska site in Warsaw, Poland, for the first insect generation. A set of untreated plots (0 droplets/tree) was established at each site as well. The treatment efficacy was estimated using two indices: (1) moth catches in pheromone traps and (2) the number of mines per leaf. Trap catches were significantly higher in the untreated plots than in the treated plots regardless of the application rate in all sites. However, there were no significant differences in leaf damage amongst all plots on each site. At the “Lazienki Krolewskie” park the attractiveness of two types of pheromone sources were compared: traps were baited with rubber septum lures or with A&K droplets. The catches of C. ohridella in traps baited with lures were lower than captures in A&K droplet-baited traps, but the difference was not significant. Possible reasons for the low efficacy of the A&K method in management of C. ohridella and reducing leaf damage are discussed.  相似文献   

15.
The efficacy of NeemAzal powder, two local neem (Azadirachta indica ) products [neem seed powder (NSP) and neem seed oil (NSO)], as well as a local Lamiaceae, Plectranthus glandulosus leaf powder, applied at four different rates for the control of Sitophilus zeamais was determined. Mortality was recorded 1, 3, 7 and 14 days after S. zeamais infestation, followed by the determination of F1 progeny production. Grain damage, population increase and grain germination were assessed for treated grains that were stored for 4 months. Grains treated with P. glandulosus powder and NSP had relatively low mortality (5.0–22.5%) after 3 days whereas NeemAzal and NSO had higher mortality (55.0–98.8%). Maximum mortality of 99, 100, 96 and 74% were achieved for NeemAzal (12 g/kg after 14 days), NSO (4 ml/kg after 7 days), NSP (40 g/kg after 14 days) and P. glandulosus powder (40 g/kg, after 14 days), respectively. In the same order, 7-day LC50 values were 0.02 g/kg, 1.46 ml/kg, 12.44 g/kg and 28.9 g/kg. The three neem products greatly reduced progeny emergence, while P. glandulosus powder was less effective. NeemAzal protected the grains against S. zeamais damage better than the local neem products, which in turn provided far better grain protection against the weevil damage than P. glandulosus powder. NeemAzal was superior to the local neem products in grain protection against germination loss, with P. glandulosus being the least effective. NeemAzal and NSO had sufficient efficacy to be a component of an integrated management package for S. zeamais.  相似文献   

16.
The use of biological control in turf has increased to avoid possible negative effects on humans. Entomopathogenic nematodes (EPNs) belonging to the families Steinernematidae and Heterorhabditidae have control potential against many economically important insect pests. In the present study, the efficacy of Heterorhabditis bacteriophora against a new pest on turf, Dorcadion pseudopreissi, was examined in the field. Cages (1 × 1 × 1 m) with female and male D. pseudopreissi were placed on two kinds of turf: Lolium perenne and Festuca arundinacea. After beetles had deposited eggs into the moist soil surface, the cages were removed and H. bacteriophora was applied at 0.5 million infective juveniles/m2 to half the plots. Application of H. bacteriophora caused a statistically significant reduction in numbers of beetle larvae in L. perenne plots and a non-significant reduction in F. arundinacea plots. The area damaged by D. pseudopreissi was significantly reduced by nematode application in both turf species. The number of nematodes declined after application, but small numbers could still be detected after 6 months.  相似文献   

17.
Red flour beetle Tribolium castaneum (Herbst) and rice weevil Sitophilus oryzae (L.) are considered to be the major insect pests in storage. Essential oils from aromatic plants are recognized as proper alternatives to fumigants. Thymus persicus (Ronniger ex Rech. f.) is one of these plants that have medicinal properties and is indigenous to Iran. The essential oil was obtained from aerial parts of the plant and analyzed by GC and GC–MS. Carvacrol (44.69%) and thymol (11.05%) were the major constituents of the oil extracted. In this experiment, fumigant toxicity of the essential oil was studied against T. castaneum, S. oryzae at 27 ± 1°C and 60 ± 5% RH in dark condition. The adult insects were exposed to the concentrations of 51.9, 111.1, 207.4 and 370.4 μl/l air to estimate median lethal time (LT50) values. The fumigant toxicity was increased in response to increased essential oil concentrations. The LT50 values at the lowest and the highest concentrations tested were ranged from 28.09 to 13.47 h for T. castaneum, and 3.86 to 2.30 h for S. oryzae. It was found that S. oryzae adults were much more susceptible to the oil than T. castaneum. After 24 h of exposure, the LC50 values (95% fiducial limit) for T. castaneum and S. oryzae were estimated to be 236.9 (186.27–292.81) and 3.34 (2.62–4.28) μl/l air, respectively. These results suggest that T. persicus essential oil merits further study as potential fumigant for the management of these stored-product insects.  相似文献   

18.
The purpose of this study is to investigate the insecticidal activity of two benzoic acids 2(3)-tert-butyl-4 hydroxyanisole (BHA) and 2,6-di(tert-butyl)-p-cresol (BHT); two phenolic acids 3-phenyl-2-propenoic acid (CA) and trans-4-hydroxy-3-methoxycinnamic acid (FA); and two essential oils of Eugenia caryophyllata (clove tree) and Thymus vulgaris (thyme) against Oryzaephilus surinamensis (L.) vector carrier of aflatoxigenic fungi on stored peanut. The weight loss of peanut, susceptibility of insects, Aspergillus isolation frequency from insects and peanut, and aflatoxin B1 analyses from peanut were determined. BHA, BHT, and BHA/BHT mixture were highly effective against O. surinamensis, these chemical agents give 100% mortality at the doses assayed. Essential oil of thyme at 2,000 and 3,000 ppm were highly effective against O. surinamensis, these concentrations gave 100% mortality. No Aspergillus section Flavi contamination was observed in dead insects collected from peanut treated with BHA/BHT mixture. No differences were observed in the fresh weight of pods peanut among treatments with and without chemical agents. All samples of treated peanut pods showed complete inhibition of this toxin after 120 days of storage. Our results indicate that these substances could be evaluated further for the control of pest vectors of aflatoxigenic fungi of stored peanut.  相似文献   

19.
A trial to detect optimal pin-pricking timing in evaluating the ability to form traumatic resin canals (TRCs) of Cryptomeria japonica was examined to select resistant trees to Semanotus japonicus using 14 clones in 2001 and 2002. Resistance to S. japonicus and the ability to form TRCs in the phloem was evaluated by inoculating newly hatched larvae in the bark and by a pin prick, which was conducted every 10 days (four times) on the trunk around the larval phloem-feeding period, respectively. The larval survivorship varied greatly among clones for both years. The mean appearance of newly formed TRCs was generally higher in late treatment for both years, and the tangential width of them was also higher in 2001, whereas those of pre-formed TRCs were not higher for either year. The larval survivorship did not show significant correlations with the appearance and the width of pre-formed TRCs on all treatments. However, it showed significant negative correlations with the appearance of newly formed TRCs on the second and third treatments on the 2-year-old layer, although this was not significant with the width of them. This suggests that resistant clones might have the mechanism of rapidly forming TRCs when just at the stage of newly hatched larval entering the phloem. Thus, although the relationship between the appearance and the width of newly formed TRCs is not clear, pin-pricking treatment when the newly hatched larvae just enter the bark may be one of optimal times for the evaluation of the resistance of C. japonica to S. japonicus. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

20.
The nature of damage of sweetpotato whitefly, Bemisia tabaci (Gennadius) B biotype was investigated at the vegetative stage on eggplant (Solanum melongena L., family Solanasae, variety Baiyu) under laboratory conditions (temperature 25 ± 1°C, RH 70 ± 10% and photoperiod 12 h L:12 h D). The investigations were carried out after completing one generation of whitefly on the basis of morphology, physiology and anatomy of eggplant leaf. Significant differences were observed on three morphological parameters—leaf area, leaf fresh weight, and leaf dry weight. The reduction percentages of these three parameters were 26.6, 21.8 and 19.27%, respectively. Significant differences were also observed on two physiological parameters—chlorophyll content and rate of photosynthesis. The reduction percentages of these two parameters were 9.7 and 65.9%, respectively. There were no damaged tissue observed in the epidermis and mesophyll, but there were some damage tissue observed in the vascular bundle of infested leaf. There were no damaged vascular bundles observed in the control leaves. The non-damaged vascular bundles contained both xylem and phloem; while some damaged vascular bundles contained either xylem or phloem. Associated with the non-damaged vascular bundles on whitefly infested leaves were two settled whitefly nymphs apparently deriving nutrition from phloem sap. After one generation of whitefly infestation, the number of damaged and non-damaged vascular bundles of eggplant leaf was significantly different.  相似文献   

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