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1.
The potential of the two predators,Chrysoperla carnea Steph. andCoccinella undecimpunctata Reich., as well as the two parasitoidsDiaeretiella rapae andEretmocerus mundus in an open field and under green house were conducted after several releases againstAphis gossypii, A. fabae, Brevicorine brassicae andBemisia tabaci. Double releases ofC. carnea (1∶5 predator∶aphids) achieved 100% reduction inA. gossypii after 12 days. A single release ofC. undecimpunctata (1∶50 predator∶aphids) resulted in 99.97% reduction in the same aphid. Releasing ofD. rapae to controlB. brassicae at the rate of 1∶50 resulted in 29% parasitism. ReleasingE. mundus for the control ofB. tabaci in cabbage at the rate of 5 adults/m2 resulted in 32% parasitism. Three releases ofC. undecimpunctata adults in a greenhouse cultivated with soybean, decreasedA. fabae population from 207 to 7.6 aphids/plant.  相似文献   

2.
Under laboratory conditions, when reared onPhorodon humuli aphid,Adalia bipunctata deposited 1011 ova and mean longevity of males and females was 55–73 days respectively. When reared onAphis fabae orA. fabae + Aphis craccivora diet, females ofA. pipunctata deposited 41–63 ova, and mean longevity of males and females was 20–32 days respectively. Larvae reared onP. humuli completed development in average 8.9 days, and mortality was 16.7%. Larvae reared onA. fabae, orA. fabae + A. craccivora aphids, completed development in 14–15 days, and mortality was 83–90%. It is concluded thatP. humuli aphid is an essential food forA. bipunctata, whereasA. fabae andA. craccivora aphids, are unsuitable foods.  相似文献   

3.
Bioassays and scanning electron microscopy of Conidiobolus obscurus for bamboo aphids as well as its effects on the fecundity of bamboo aphids were carried out to estimate bamboo aphid biocontrol potential. Multi-concentration bioassay and fecundity assessment were performed on aphid species of Takecallis taiwanus, Takecallis arundinariae, Melanaphis bambusae, and Metamacropodaphis bambusisucta. C. obscurus can effectively infect four species of bamboo aphids, and most cadavers appeared in the first 2 days after inoculation. The final mortalities reached 74–91 % at high concentrations of conidia among the tested species. Based on the fitted time–concentration–mortality models, the estimates of the median lethal concentration (LC50) of the fungal conidia differed significantly among different aphid species and decreased with observation days. The lowest LC50 was estimated to be 57 conidia mm?2 for T. taiwanus on day 5 after conidial shower. Moreover, the C. obscurus-infected aphids only produced 3.9–18.2 % progeny of the corresponding healthy aphids, which strongly presented fungal influence on host fecundity. In conclusion, C. obscurus has the ability of restraining the development of bamboo aphid populations, which is suitable for further application in aphid biocontrol in bamboo forests.  相似文献   

4.
Exposure to standard solution S extract ofPunica granatum, Thymus vulgaris andArtemisia absinthium for 72 h reduced the numbers of active nematodes by 100% forMeloidogyne incognita and by 95.7%, 71.4% and 42.9% forHelicotylenchus dihystera, respectively. Exposure to S/2 dilutions for 72 h reduced nematode motility by 100%, 77.3 and 72.7% forM. incognita, and by 92.9%, 37,1%, and 37,1% forH. dihystera, respectively. As exposure to S and S/2 extracts ofCitrullus colosynthis andRicinus communis reduced nematode motility by less than 32% forM. incognita and by less than 30% forH. dihystera. WhenM. incognita andH. dihystera were transfered to water for 72h, more than 85% of the individuals resumed normal movement at all extract dilutions except S ofA. absinthium andT. vulgaris and S and S/2 ofP. granatum. However, recovery ofM. incognita was more less than that ofH. dihystera. Exposure to S extracts ofP. granatum andT. vulgaris for 30 days reduced egg-hatching ofM. incognita by 100% and by 98.7% for S/2 dilutions. Also, 98.7% reduction in the egg-hatching was obtained by S ofA. absinthium. Extracts ofC. colosynthsis andR. communis gave less egg-hatching inhibition. Acetylcholinesterase (AChE) activity was suppressed by more than 75% inH. dihystera treated with S of each ofP. granatum, T. vulgaris andA. absinthium. However, the former extract gave the highest AChE inhibition (98.7%). When nematodes were treated with oxamyl (Vydate 24%), AChE activity was suppressed by 53.3%. The other extract dilutions suppressed AChE activity by less than 50%.  相似文献   

5.
The essential oils of four medicinal plants belonging to Lamiaceae were explored for phytonematode control. The four oils inhibited (P<0.05) nematode motility butMentba spicata was generally more effective in reducing the numbers of active nematodes followed byThymus vulgaris, Majorana bortensis andMentba longifolia. The main corresponding compound of each oil, determined by GLC analysis, was carvone (58.14%), P-cymene (40.5%), terpinen-4-ol (41.6%) and carvone (70.36%). Soil stages of the reniform nematode were more affected by the oil than those of the ring and lance nematodes. When transferred to water, the total nematodes that regained their activeness ranged from 12% forT. vulgaris to 60% forM. longifolia. The four 0.1 oil solutions inhibited more than to about 3.5% at the control. The content of oxygenated compounds in these oils ranged from 45.79% to 96.5% and may be partially responsible for the nematicidal effects.  相似文献   

6.
The insecticidal activity of acetone extracts ofCymbopogon citratus (DC) Stapf.,Momordica charantia L.,Zingiber officinale (Ros.),Xylopia aethiopica (Dunal) A. Rich.,Ocimum gratissimum L. andAframomum melegueta (Ros.) K. Schum against the cowpea aphid,Aphis craccivora Koch was investigated.Z. officinale andA. melegueta extracts had the greatest effect in causing mortality ofA. craccivora and inhibiting its reproduction. Extract fromM. charantia caused high nymphal mortality whilst extract fromC. citratus also caused significant nymphal mortality, reduction of life span of adult aphids and inhibition of aphid reproduction.With 3 tables  相似文献   

7.

The cabbage aphid Brevicoryne brassicae is a notorious agricultural pest that specializes on plants of the Brassicaceae family, which are chemically defended by glucosinolates. By sequestering glucosinolates from its host plants and producing its own activating enzyme (myrosinase), this aphid employs a self-defense system against enemies paralleling that in plants. However, we know little about the metabolic fate of individual glucosinolates during aphid sequestration and activation and about the biochemical effects of this defense on aphid enemies. Here, we probed these questions focusing on B. brassicae and a predatory lacewing, Chrysoperla carnea. We found that distinct glucosinolates were accumulated by B. brassicae at different rates, with aliphatic glucosinolates being taken up more quickly than indolic ones. B. brassicae myrosinase enzymatic activities toward different glucosinolates were strongly correlated to their rates of accumulation in vivo. Surprisingly, after simulated predation, the production of toxic isothiocyanate products (ITCs) was quantitatively outweighed by less toxic products such as nitriles and ITC-conjugates. Nevertheless, the defensive cocktails significantly impaired C. carnea development. Tissue-specific quantification of glucosinolate metabolites revealed that the lacewings employ both conjugation and mobilization to reduce the toxicity of aliphatic ITCs, but these strategies were only partially effective. These results clarify the metabolic fates of glucosinolates after sequestration by an aphid herbivore and further in a higher trophic level, as well as the consequences for predator survival and development, and might be instructive for integrative pest management approaches targeting the cabbage aphid.

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8.
The rose-grain aphid,Metopolophium dirhodum (Wlk.), is a species living onRosa spp. as winter hosts and Gramineae as summer hosts. Thus, the planting of roses along roadsides and highways may be of importance in connection with the migration of the aphids to cereals. In March 1982 the nymphs hatched from eggs, which were laid in autumn on long shoots. One or two days after hatching they fed on buds in batches up to 15 individuals. Somewhat later they dispersed on the hostplants. The nymphal mortality of the first generation was high, namely about 79%. For further population development the number of fundatrices was less important due to their high reproduction capacity. Nymphs and adults of the first generation often changed their feeding site on the shoots. The specimens of the 2nd and 3rd generation were more stationary and formed dense colonies. The population density drastically increased during the 3rd generation. The development of the aphid populations on the primary host took place during 2–3 generations and lasted until the beginning of June, when the winged forms left the hosplant. In the second generation, i. e. at the beginning of May, the first emigrantes appeared and the size of the aphid colonies increased up to 115 individuals. Most colonies consisted of less than 11 aphids namely 30.9%. Natural enemies were present in large numbers during the end of May when the populations of aphids decreased due to emigration. They did not influence the density of aphid colonies, except the predacious larvae of hover-flies. Trophobiosis between ants and rose-grain aphids was not observed on the primary hostplant.  相似文献   

9.
As very little is known about the impact of cold pre-treatments on insecticidal toxicity to the surviving stored-product insects, we examined the effects of cooling (?5 °C) on the toxicity of five contact insecticides to Sitophilus granarius adults from three populations (laboratory, field and selected). We determined: (a) weevil lethal time after exposure to ?5 °C, (b) the effects of two cold pre-treatments (LT20 and LT50—lethal time for 20 and 50 % of exposed adults) on 24 and 72 h recovery rates of laboratory adults after exposure to five insecticides and (c) deltamethrin, dichlorvos and malathion toxicity to two weevil populations with altered insecticide susceptibility after exposure to the LT20 and LT50 pre-treatments. The tested S. granarius populations showed no significant differences in their susceptibility to cooling. All insecticides except dichlorvos were more toxic to the laboratory weevils after 24 h than after 72 h recovery from the LT20 pre-treatment. Dichlorvos and deltamethrin were more toxic to the other two populations after 72 h of recovery. Comparing the effects of cold pre-treatment and non-treatment on the laboratory strain, no significant increase in the toxicity of insecticides was detected, while only deltamethrin was significantly more toxic to the field and selected populations recovering for 24 h (12.1 and 11.0 times, respectively) and 72 h (6.9 and 36.6 times) from the LT20 pre-treatment. In conclusion, only the shorter of the two cold pre-treatments was found effective in terms of increasing the insecticidal toxicity, especially against the populations with altered susceptibility to insecticides.  相似文献   

10.
For the control of the aphid speciesMacrosiphum euphorbiae, an important aphid species on greenhouse cut roses in Austria, with the parasitoidAphelinus abdominalis, trials were carried out in the rose varieties Frisco, Kardinal and Vivaldi at a commercial producer on a greenhouse area of 630 to 700m2. Both the inundative release of 9,6A. abdominalis/m2 in total and the release of 2,2A. abdominalis/m2 in total, within an open rearing system were investigated and the percentage of infested rose shoots in combination with the degree of infestation were evaluated. The results showed that an effective reduction of present or newly developing aphid populations was possible for several weeks under the conditions of a commercial greenhouse production. The amount of insecticides used against aphids decreased by up to 75% in comparison to greenhouses were only chemical pest control was carried out. The suitability of the different introduction methods ofA. abdominalis for the control of aphids on greenhouse cut roses is discussed.  相似文献   

11.
Zusammenfassung Die Wirkung von 9 Handelspräparaten von Insektiziden (ein Carbamat, 2 Organophosphate, 4 chlorierte Hydrocarbone und 2 chlorierte Phosphorverbindungen) auf das Vorkommen vonCoccinella undecimpunctata undScymnus interruptus in einer Baumwoll-Plantage in Assiut (Ober-Ägypten) wurde geprüft Eine Fläche von 2 Feddan (= 8400 m2) wurde willkürlich in 40 Parzellen geteilt (4 Kontrollparzellen und 4 × 9 Behandlungsflächen) gemäß einem vollständig zufälligen Block-System. Die Käfer wurden in situ auf 50 Sträuchern pro Fläche knapp vor der Behandlung und am 3., 7. und 10, Tag hernach gezählt. Die Behandlung wurde viermal in Intervallen von 15 Tagen, beginnend Mitte Juni, wiederholt. Die Ergebnisse waren folgende:1. Die stärkste Anfangswirkung gegenCoccinella hatte Toxaphen/DDT/Delnav, Sevin, Lebaycid und Methyl-Parathion (70–72% Sterblichkeit in 3 Tagen nach der ersten Behandlung). Die geringste Anfangswirkung hatte Toxaphen/Dilan (um 43% Sterblichkeit in 3 Tagen).2. Die stärkste Anfangswirkung gegenScymnus hatte Sevin (um 88% Sterblichkeit in 3 Tagen) gefolgt von Toxaphen (76% Sterblichkeit). Die geringste Anfangswirkung hatte Toxaphen/Dilan (um 29% Sterblichkeit).3. Die Anfangswirkung stieg mit der Zeit nur in einigen Fällen an, z. B. bei Sevin und Lebaycid gegenCoccinella und bei Toxaphen/Dilan und Toxaphen/DDT/Delnav gegen.Scymnus.4.Scymnus scheint gegen gewisse Verbindungen empfindlicher zu sein alsCoccinella, z. B. gegen Sevin und Toxaphen, und weniger empfindlich gegen andere Verbindungen, z. B. Lebaycid.5. In den meisten Fällen stieg bei Wiederholung der Behandlung die reduzierende Wirkung bei beiden Insekten-Arten an. Solch eine verstärkte Wirkung von Sevin aufCoccinella trat bald und stetig ein.
Summary The effect of nine commercial insecticides (one carbamate, 2 phosphorous compounds, 4 chlorinated hydrocarbons and 2 combinatins of chlorinated and phosphorous compounds) on the abundance ofCoccinella undecimpunctata andScymnus interruptus on cotton was tested in an area of two Feddans (= 8400 square meters). The area was divided into 40 plots (4 controls and 4 × 9 treatments) according to a complete randomized block system. The beetles were counted in situ on 50 bushes/plot immediately before treatment and on the 3rd, 7th and 10th day thereafter. Application was repeated 4 times at 15 days intervals beginning from mid June. The results showed that:1. The strongest initial effect onCoccinella was that of toxaphene/DDT/delnav, sevin, lebaycid and methyl-parathion (70%–72% mortality in three days after the first application); the weakest initial effect was that of toxaphene/dilan (about 43% mortality in 3 days).2. The strongest initial effect onScymnus was that of sevin (about 88% mortality in 3 days), followed by toxaphene (about 76% mortality). The weakest initial effect was that of toxaphene/dilan (about 29% mortality).3. The initial effect increased by time only in a few cases, e. g. that of sevin and lebaycid onCoccinella and that of toxaphene/dilan and toxaphene/DDT/delnav onScymnus.4.Scymnus seems to be more sensitive thanCoccinella to certain compounds, e. g. sevin and toxaphene and less sensitive to other compounds e. g. lebaycid.5. In most cases repetition of application resulted in an increasing detrimental effect on both insect species. Such a cumulative effect was readily observed and rather steady in the case of sevin onCoccinella.
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12.
Host plant preference of the Russian wheat aphid Diuraphis noxia (Kurdj.) was studied on 11 cultivars of 9 plant species: winter barley, spring barley, winter wheat, spring wheat, rye, oat, Triticale, canary grass, red millet yellow millet and maize. Seeds of the host plants were sown in a circle near the edge of pots. The host plant choice was evaluated 24 hours after releasing 55 Diuraphis noxia female adults in the middle of each pot. The suitability of different hosts for aphid development was evaluated 2, 7 and 14 days after infestation based on the mean number of Russian wheat aphid individuals per plant. Red millet, yellow millet and maize were chosen by significantly fewer aphids than grain crops. Winter and spring barley were chosen as hosts most frequently, and the progeny production was also the highest on these plants. The growth rate of D. noxia was significantly affected by the host plants and the date of assessment and their interaction.  相似文献   

13.
Studies were conducted in cucumber fields to evaluate the standard and reduced dosage rates of 5 insecticides for control the cotton whiteflyBemisia tabaci (Genn.) and melon aphidAphis gossypii Glov. and effect of insecticide application on associated parasites and predators. Eggs of whitefly appeared to be less susceptibility to all treatments (max. 66% reduction) than larval and pupal stages. Populations of larval and pupal stages of whitefly were significantly reduced in all treated plots. For example (larvae on day 10 after treatment with ethiofencarb, diafenthiuron, and chlorpyrifos methyl 67, 50, and 68% pupae 68, 69, and 75%). Two aphelinid parasitoids,Eretmocerus mundus Mercet andProspaltella lutea Masi, were the most primary important parasitoids of the whitefly pupae in all test plots. Percent parasitism, in most treated plots, were slightly affected as a result of insecticide application. However, all tested insecticides and dosage rates caused severe suppression of emergence of adult parasitoids. Moreover, longevity of adult parasitoids were highly decreased. Populations of the melon aphid were extremely reduced, especially by ethiofencarb and diafenthiuron. Populations of predator species (Chrysopa carnea Steph.,Coccinella undecimpunctata Reiche andSyrphus spp.) were reduced in all treated plots. However, ethiofencarb applied at rates as low as 208.4g a.i./1001 provided equally effective aphid control and conserved numbers of insect predators in the treated plots. Also, the prothiofos and chlorpyrifos methyl applications at rates as low as 166.7 g a.i./1001 kept aphid numbers below than those in control and caused a smaller reduction in the combined populations of insect predators.  相似文献   

14.
Several tests were conducted in the greenhouse to compare the reproduction ofM. chitwoodi andM. fallax on some field crops grown at the type locality ofM. fallax and in the region were both nematodes occur. In addition some related crops andTagetes erecta andT. patula were also tested. The French bean cv. Masai, the chicory cvs Hybrid F1, Mid-Early and Groenlof, the dahlia cv. Vuurvogel and an unknown cv. of borage supported low populations of bothM. chitwoodi andM. fallax. The French bean cvs Strike and Groffy showed a differential response toward both nematodes: both cvs were good hosts forM. chitwoodi and non-hosts forM. fallax.With 1 table  相似文献   

15.
The introduction of three killing agents (propylene glycol, DDVP and water) inside perforated probe traps was evaluated for their efficiency in trapping Coieoptera adults infesting stored cereals. The experiment was carried out in nine steel bins containing wheat, located in Central Greece, in August 1997. For the most of the 26 beetle species found, no significant differences were observed among treatments. ForSitophilus spp.,Typhaea stercorea, Aloasverns advena, Oryzae-philus surinamensis, Latheticus oryzae, Palorns ratzeburgii, P. subdepressus, andTenebroides mauritanicus, significantly less adults were found in the control traps (with no killing agent). Significant differences among three killing agents were observed only forT. stercorea andT. mauritanicus. Given that the traps supplied with killing agents were found to contain adults even in locations where control traps did not, is concluded that the addition of killing agents has increased the detection sensitivity of traps.  相似文献   

16.
The occurence ofSipha (Rungsia) elegans is recorded in 11Aegilops species and in two wildTriticum species grown on an experimental plot in Praha-Ruzyn in 1993–1995. Abundance ofS. elegans varied in various years, and the infestation of species tested also differed. The highest aphid number, 0.91 individuals per tiller, was recorded in 1995 at the latest date of counting. In 1994, at the earliest counting date, the lowest aphid number was recorded, i.e. 0.14 individuals per tiller. The highest proportion ofS. elegans, 42–48% of its total number on plants, was recorded in wild einkornT. boeoticum. In all yearsAe. cylindrica, Ae. tauschii andAe. triuncialis were more infested than otherAegilops spp. tested. The aphid number on remaining eightAegilops spp. were either low or varied in particular years.A certain aphid number was observed on spring wheat plants in isolation strip in all three years. On bothAegilops and wheat plantsS. elegans preferred the upper surface of the flag leaf tips where it caused clearcut yellow patches.With one figure and one table  相似文献   

17.
AdultCoccinella septempunctata, a coccinellid predator of the bean aphidAphis fabae Scop., responded to aqueous extract containing kairomones of the prey. The crude aphidextract was topically dropped onto either clean leaves ofVicia faba or clean Petri-dishes. After application of aqueous-extract at different aphid densities, the predator showed variations in the attractivity and searching behaviour in comparisons with control. The variations are summarized as follows: (1) the aqueous-extract of aphids attract or directC. septempunctata adults to the treated vials at all aphid densities. The number of attracted or directed coccinellid adults was directly proportional with aphid concentrations; (2) the predatorC. septempunctata adult intensified its searching behaviour by increasing the total path length walked; (3) the number of turns exhibited is significantly higher as compared with those of control; and (4) the arrested time spent by coccinellid adults with treated plant is much more than that with clean plant at all aphid densities. The present results show that the aphid aqueous-extract contains the active ingredients (kairomone) which induce considerable changes in the searching pattern of the predator coccinellid adults.  相似文献   

18.
During 1996 and 1997, populations of aphids and whiteflies and their parasites were studied in plastic greenhouses under a chemical control program and in those free of pesticides. In the greenhouses free of pesticides, the parasite A. colemani destroyed 14.7?% of the aphids. B. tabaci had no effect on the cucumbers during the spring cultivation. However, it attacked the autumn cultivation. The parasite E. mundus killed 30?% of these nymphs. The parasite A. colemani parasitized up to 10?% of aphids on tomato plants in greenhouses free of chemical pesticides. The parasite E. mundus killed 15.7?% of whitefly nymphs. In greenhouses under a chemical pesticides program, aphids and whiteflies were found on the plants at the end of the plantation season, after the pesticide spraying had stopped. Although the pest population was low, the parasite A. colemani parasitized 8?% of the aphid population. Whiteflies were not found on tomato plants in greenhouses under extensive pesticides use.  相似文献   

19.

White spruce (Picea glauca (Moench) Voss) is host to several pests, including the white pine weevil (Pissodes strobi (Peck)) and the green spruce aphid (Elatobium abietinum (Walker)). The larvae of the white pine weevil damage spruce leaders by consuming the cortex while the green spruce aphid is a defoliator. White spruce emblings (seedlings produced by culturing tissues from seed embryos) from 18 families previously ranked for resistance to the white pine weevil were defoliated to varying degrees by the green spruce aphid in a natural outbreak that developed within a holding shadehouse. A strong relationship was shown between damage caused by the aphids and weevil resistance. Emblings ranked as highly weevil - resistant sustained significantly less aphid defoliation.  相似文献   

20.
Ant–aphid mutualisms, in which ants tend aphids, which in turn provide honeydew to the ants, are widespread and have been shown to affect plant growth. In boreal forests the effect of ant–aphid mutualism on tree growth can vary with stand age, because forest clear-cutting harms the ecologically most dominant ant partner in such mutualisms, wood ants (Formica rufa group). We studied whether the mutualism between wood ants and Cinara aphids affects the growth of boreal Norway spruces (Picea abies L. Karst.) in stands of different ages. In boreal forests, conifers, unlike deciduous trees, have only few defoliating insects, and therefore we expected the growth loss of conifers due to sap sucking by aphids not to be compensated by reduced insect herbivory due to predation by wood ants. The study was conducted in medium-fertile spruce-dominated stands in eastern Finland. We used stands of four different age classes (5, 30, 60 and 100 years) and selected ten spruces heavily visited and ten spruces lightly visited by ants around five medium-sized ant mounds in each stand age class. The access of ants was blocked on half of the trees in both groups. In the 5-year-old stands, the mean annual height growth of individual heavily visited seedlings was 16.3% greater than in the ones where ant traffic was blocked, but this difference was not significant. In the 30-year-old stands, the mean annual radial growth of the heavily visited spruces was 7.3% smaller than in trees where ant traffic was blocked, and this difference was significant. The mutualism had no significant effect on the radial growth in the 60- and 100-year-old stands. In the 60-year-old stands, however, the spruces that were visited heavily prior to the beginning of the study grew significantly less relative to their past growth than the initially lightly visited trees during the study. This suggests that the ant–aphid mutualism may have long-term effects on tree growth. The ant–aphid mutualism had no significant effect on the growth at the stand level. The results indicate that ant–aphid mutualism can have a significant effect on the growth of individual spruces, but the effect is negligible at ecosystem level.  相似文献   

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