巧治桃树蚜虫

桃树上的蚜虫常见的有桃挑蚜、桃粉蚜和桃瘤蚜3种。这3种蚜虫都以刺吸式口器吸食桃树嫩梢和叶片汁液，被害后叶片苍白卷缩，严重的脱落，影响花芽形成．削弱树势。     

桃树“二虫三病”的防治

桃树＂二虫三病＂即桃蚜虫、桃蛀野螟和白锈病、流胶病、缩叶病,是桃园生产中主要防治对象。 一、桃蚜虫。危害严重的是桃蚜和桃粉蚜,以成虫和若虫密集在幼梢和叶背吸食汁液。受害桃叶向背面作不规则卷缩,卷叶上有粘液,最后干枯脱落。受桃粉蚜危害的叶片纵合成筒状，卷叶中常有白粉，严重时叶片脱落。     

观赏桃花桃粉蚜的发生及防治

桃粉蚜又名桃大尾蚜，是观赏桃花常见的主要虫害之一，同时也危害李、杏、梅及禾本科植物。观赏桃树受害后，叶片畸形、卷缩、萎蔫，果实发育不良甚至枝梢干枯，同时排泄蜜露，诱发烟煤病，严重影响桃树的生长、发育和观赏价值。形态特征成虫分有翅和无翅2种类型，以无翅蚜为多。无翅蚜体长2毫米左右，绿色体表被有蜡状白粉。有翅蚜体型较无翅蚜小，头部及胸部为淡黑色，腹部黄绿色被有白粉，触角较体短。卵椭圆形。发生规律每年发生10余代。以卵在枝条和芽缝里越冬。来年3月无翅雌蚜出现，初期群集芽上，待展叶和新梢抽生后，即密集在叶背…     

桃树"二虫三病"防治方法

桃树"二虫三病",是桃园生产中主要防治对象。一、桃蚜虫危害严重的是桃蚜和桃粉蚜,以成虫和若虫密集在幼梢和叶背吸食汁液。受害桃叶向背面作不规则卷缩,卷叶上有粘液,最后干枯脱落。受桃粉蚜危害的叶片纵合成筒状,卷叶中常有白粉,严重时叶片脱落。     

桃树“二虫三病”防治方法

桃树“二虫三病”,是桃园生产中主要防治对象。 一、桃蚜虫。危害严重的是桃蚜和桃粉蚜,以成虫和若虫密集在幼梢和叶背吸食汁液。受害桃叶向背面作不规则卷缩,卷叶上有粘液,最后干枯脱落。受桃粉蚜危害的叶片纵合成筒状，卷叶中常有白粉，严重时叶片脱落。     

介绍两种防治桃蚜的有效方法

桃蚜是桃树的主要害虫之一,发生普遍,为害严重,防治不当常造成大量落叶,影响树势及果实的产量和质量。生产上果农多喜欢在展叶开花后喷药防治,每年喷3-4次药仍不能取得较好的效果,常常是喷了药,也卷丁叶,落了果,给果农带来了不应有的损失。根据蚜虫的发生规律,必须抓住春季桃树未展叶前这个关键时期治早、治小。现介绍两种防治桃蚜的有效方法。     

蚜虫的防治

蚜虫,俗称腻虫,属同翅目、蚜总科。蚜虫种类繁多,除五倍子蚜是经济益虫外,绝大多数是农林害虫。在陕西分布的主要有松大蚜、刺槐蚜、柏大蚜、杨毛蚜以及危害果树的苹果蚜、桃蚜和杏蚜等,蚜虫年发生代数多,繁殖快,数量大,在15～22℃,相对湿度80％,繁殖比较适宜,温度越高、发育越快,     

桃树采果后的管理

桃树采果后至秋季落叶前,是营养积累和花芽分化的关键时期,管理的好坏直接影响桃树越冬及来年的结果,应掌握以下要点:一、喷药防治“回迁蚜”。桃树采果后,周围菜园和玉米田的有翅蚜虫、红蜘蛛等会相继迁回桃树交配产卵越冬。成蚜和若蚜群集在桃叶背部刺吸汁液,使叶片变黄卷曲,严重影响桃树生长。可用5%多菌灵800倍液、5%克菌丹可湿性粉剂50倍液或40%乐果乳油500倍液等防治。二、科学施肥。采果后,结合中耕除草进行施肥。对结果多、树体营养消耗大的桃树要早施、重施。在树冠滴水线处开50厘米深的环状沟或放射状沟,每株施人粪尿或厩肥30~40…     

蒲螨对几种半翅目林业害虫的控制作用

笔者研究了蒲螨对松大蚜、苹果蚜、栾多态毛蚜、桃粉蚜、国槐蚜虫等半翅目蚜虫的控制作用。结果表明,蒲螨对松大蚜、苹果蚜、栾多态毛蚜、桃粉蚜4种蚜虫的控制效果较好,寄生4 h后和8 h后的死亡率均在80%以上;蒲螨对国槐蚜虫的控制效果较差,4 h后未见蚜虫死亡,8 h后死亡率仅为26.7%,24 h后死亡率为38.9%,48 h后死亡率为51.2%.     

阿维菌素对桃树主要害虫防治效果评价

试验结果表明，阿维菌素是防治桃树害虫的一种较好的药剂，该药剂对桃树主要害虫山楂叶螨、桃蚜、桃粉蚜、桃一点斑叶蝉均具有较好的防治效果，持效期10天左右，研究还探明了该药刺防治不同桃树害虫应使用的有效浓度。     

Weeds,aphids, and specialist parasitoids and predators benefit differently from organic and conventional cropping of winter cereals

The aphid–natural enemy interaction in winter wheat fields constitutes a complex system that has been frequently studied because of its implication for biological control. However, not all of the aphids living in cereal fields are crop pests, as there are also aphids living on weeds that may serve as alternative hosts or prey for aphid parasitoids or predators. In this context, a concomitant survey of the plant and insect communities was conducted to understand how different plant communities affect the abundance and richness of aphids and the interactions with their natural enemies. The plant community was split into functional groups (grasses, legumes and forbs), and the aphid community was divided into feeding groups according to their host preferences (specialists in grasses or forbs). The grass aphids, which dominated the total aphid catches, responded positively to grass cover, which was particularly enhanced in the conventional fields. Conversely, the forb aphids, which mainly conditioned the total species richness of the aphids, were closely correlated with the local abundance of legumes. The system of cereal aphid-parasitoids was enhanced in the conventional fields, where the abundance of grasses was higher, whereas the legumes of the organic fields indirectly played a key role in enhancing the richness of the parasitoids and the abundance of predators. Our findings indicate that a bottom-up effect exists throughout the plant community, aphids, and aphidophagous insects and that plant community characteristics should be considered to better understand cereal aphid control.     

Beobachtungen zur Entwicklung der Frühjahrspopulationen vonMetopolophium dirhodum (Wlk.) auf dem Winterwirt

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.     

Host acceptance behavior of the parasitoid Aphelinus mali and its aphid-host Eriosoma lanigerum on two Rosaceae plant species

The presence of a natural enemy in a habitat refuge is no guarantee of emigration by these into crop fields, when pest population outbreaks occur. Parasitoids from a refuge may not prefer foraging on the pest crop, exhibiting host fidelity, and therefore not constituting a source of natural enemies for improving biological control. An effective refuge must not only be a suitable sink for natural enemies, providing an acceptable host when these are not present in the crop, but it must also be a suitable source of parasitoids that readily accept the aphid-host on the crop. Therefore, crop-originated parasitoids would have to accept pests from the refuge as hosts to lay eggs in, and refuge-originated parasitoids would have to accept and lay eggs in pests from the crop. We here study the host fidelity of populations of Eriosoma lanigerum originating from two host plants (firethorn and apple) through reciprocal transfer experiments. Thereafter, the host fidelity of parasitoids from populations in the two host plants (firethorn and apple) was assessed. Reciprocal transfer experiments of parasitoids did not show an association between apple-originated parasitoids and their preference for any of the aphid hosts. Conversely, parasitoids from firethorn exhibited a higher number of attacks and in less time when aphids from apple were offered, suggesting a preference for apple-originated aphids. If future field work confirms these findings, firethorn could become an important management tool for enhancing biological control of woolly apple aphid in apple orchards, without being a substantial source of aphids.     

Seasonal parasitism of cereal aphids in a Mediterranean arable crop system

We monitored winter cereal fields in a Mediterranean arable crop system to obtain information about the aphid parasitoid species composition and the aphid–parasitoid interactions through the whole cropping cycle. Nine species of aphid primary parasitoids (Hymenoptera, Braconidae, Aphidiinae) were identified. The most abundant species were Aphidius rhopalosiphi, Aphidius matricariae, Aphidius ervi and Lysiphlebus testaceipes. The genus Aphelinus sp. (Hym., Aphelinidae) was also identified. We determined seasonal host–parasitoid associations over the entire cereal crop cycle. A number of new such associations were recorded, which were previously unknown in Spain and Europe. Our results indicated broad associations of L. testaceipes and A. matricariae with cereal aphids; furthermore, the association of Aphelinus sp. with several cereal aphid species was also substantial. In the NE of the Iberian Peninsula, the cereal aphid parasitoids that we identified are able to develop throughout the crop season on one or more host species. Thus, the main aphid species can be parasitized effectively throughout the entire cereal crop cycle. We discuss the role of cereal aphid parasitoids in the region in the context of our experimental results.     

The influence of the aphid-specific pathogen Conidiobolus obscurus (Entomophthoromycota: Entomophthorales) on the mortality and fecundity of bamboo aphids

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.     

竹卵圆蝽生物学特性及其天敌种类调查研究

通过调研，基本摸清了竹卵圆蝽的生物学特性和天敌种类。该虫在湖南省1年发生1代，3月中旬，越冬若虫爬行上竹群集竹秆、竹枝取食毛竹汁液；5月中旬羽化成虫；6月中下旬开始交尾产卵；11月中旬以2～4龄若虫下至地面笋壳、枯枝落叶层下越冬。该虫天敌种类较多，其中卵期有5种寄生蜂。     

把竹主要害虫生物学特性观察

据观察竹笋夜蛾在湖北阳新 1a发生 1代 ,以卵于禾本科杂草下部枯草上或竹基部笋箨上越冬 ,4月中下旬以 2龄幼虫从杂草上转主蛀入把竹笋危害 ;一字竹象和小竹象 1年 1代 ,以成虫于土下 8～1 5cm深的土茧中越冬 ,4月下旬成虫出土上把竹笋吸食笋肉 ,进行补充营养 ,随后进行交尾、咬产卵孔产卵 ,幼虫孵化后取食笋肉危害 ;江苏泉蝇每年 1代 ,以蛹在土中越冬 ,3月下旬为雄虫羽化高峰 ,雌虫的出现高峰在 4月中旬 ,上把竹笋取食、交尾、产卵 ,幼虫危害竹笋 ,发生腐烂 ,造成退笋     

Host plant preference of Diuraphis noxia (Kurdj.) (Hom., Aphididae)

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.     

Disruptive effects of non-specific airborne and substrate-borne vibrations on aphids

Insects are known to be negatively impacted by noise from anthropogenic sources. Recently, pest control methods have been developed using specific airborne (sound) and substrate-borne vibratory signals. However, there is limited information available on the effects of non-specific vibrations on pest insects, especially those not known to use sound or vibration for communication. Here, we tested whether non-specific substrate-borne or airborne vibrations (white noise) cause reductions in the number of aphids of three species on single plants in short-term (24 h) laboratory trials. Substrate-borne vibrations transmitted through the host plant reduced total numbers of all three species (45 to 62% reductions in total aphid numbers), while airborne vibrations played through speakers had no detectable effect. The effect of substrate-borne vibrations on aphid numbers appeared to be mostly due to inducing aphids to leave the plant, rather than reducing the reproductive output of remaining aphids. To our knowledge, our results provide the first proof-of-concept indicating that non-specific substrate-borne vibrations can affect pests not known to use vibrations to communicate and should be explored further as a physical pest control method. Future research in this area is needed to investigate longer-term effects of non-specific vibrations on pests, their host plants, and their natural enemies.

     

Greenhouse trials for the control of aphids on cut-roses with the chalcidAphelinus abdominalis Dalm. (Aphelinidae,Hymen.)

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.