植物提取物和常用药剂对蚜虫重要天敌瓢虫孵化、存活和捕食效能的影响

为解决目前化学合成杀虫剂长期大量使用所带来的“3R”问题 ,有必要从对人畜无毒或低毒、对害虫天敌安全的植物和其它天然产物中筛选与环境相容性好的物质作为害虫控制的手段。已经从 63种植物中筛选出两种对蔬菜蚜虫有较好控制作用的植物苍耳 Xanthium sibiricum Petr.et Widd.和白蝴蝶Syngonium podophyllum Schott。报道该两种植物乙醇提取物以及几种常用天然源药剂 (鱼藤酮精、机油乳剂和 0 .3%印楝素乳油 )对深圳菜区蚜虫重要天敌瓢虫 (六斑月瓢虫 Menochilussexmaculata( Fabricius)和狭臀瓢虫 Coccinella trasversalis Fabricius)的影响。结果表明 ,两种植物提取物 ( 0 .0 4 g DW/ml)对所测试瓢虫的孵化、存活和捕食效能与对照之间在 0 .0 1或 0 .0 5水平均无显著差异 ,表明两种植物提取物对瓢虫安全、无明显毒性。而鱼藤酮精 ( 80 0× )、机油乳剂 ( 4 0 0× )和 0 .3%印楝素乳油 ( 2 0 0 0× )在所测试的浓度对瓢虫卵的毒性较强 ,瓢虫卵的孵化率明显降低 ,仅有对照瓢虫卵孵化率的 7.74%～ 1 4.31 % ,因此应避免在田间瓢虫大量产卵的季节使用。苍耳和白蝴蝶提取物对蚜虫的重要天敌瓢虫没有负面影响 ,可以考虑作为保护十字花科蔬菜免遭蚜虫危害的植物保护剂配方。     

七星瓢虫成虫对烟蚜的捕食作用

对七星瓢虫CoccinellaseptempunctataL .成虫对烟蚜Myzuspersicae的捕食作用进行了定量研究。七星瓢虫成虫对烟蚜的功能反应属HollingⅡ型反应 ,拟合的圆盘方程为Na =1 .1 5 76Nt ( 1 +0 .0 0 3 48Nt) ,χ2 检验表明圆盘方程理论值与实测值相符。捕食选择试验表明在烟蚜、烟青虫Helicoverpaassaut(Guenee)卵和 1龄幼虫 3种猎物中 ,七星瓢虫成虫最喜好烟蚜。七星瓢虫成虫对自身密度的功能反应用Watt模型拟合为A =2 90 .0 3P-0 .7584,其捕食作用率与个体间相互干扰作用的关系用Hassell模型拟合为E =0 .8783 7P-0 .1 0 0 94。文中进一步就烟田中七星瓢虫的保护利用进行了讨论。     

两种瓢虫对刺槐蚜的捕食作用

在实验室条件下研究了龟纹瓢虫成虫和异色瓢虫成虫对不同密度刺槐蚜的捕食功能反应,符合HollingⅡ 型功能反应模型,其模型分别为:Na=0.4050/1+0.0073N和Na=0.4227N/1+0.0046N,x2值均小于X20. 05=9.49,最大捕食量分别为55.6头和90.9头.圆盘方程理论值与实测值相符.随着瓢虫密度的增加,单个瓢虫捕食率下降,龟纹瓢虫和异色瓢虫自身密度的干扰效应模型分别为:E=0.208P-0.235,E=0.236P-0.324.     

龟纹瓢虫成虫对麦蚜捕食作用的研究

通过田间调查与室内观察表明,龟纹瓢虫对麦蚜的追随关系紧密,其对麦蚜的功能反应属Holling的Ⅱ型反应。捕食若蚜的圆盘方程为Na=0.9929N/1+0.0127N,捕食成蚜的圆盘方程为Na=1.2243N/1+0.0571N,一昼夜对若蚜和成蚜的捕食量上限分别为78头和22头。     

异色瓢虫成虫对麦二叉蚜的捕食作用模型

通过异色瓢虫雌,雄成虫对麦二叉蚜捕食作用研究,得出：1．异色瓢虫雌、雄成虫对麦二叉蚜捕食作用的功能反应均是HollingⅡ型反应;2．异色瓢虫捕食麦二叉蚜时,同等数量的异色瓢虫雌雄混合的干扰作用大于同一性别成虫间的干扰作用;3．异色瓢虫雌、雄成虫均喜好捕食低龄若蚜．     

饥饿对七星瓢虫捕食作用的影响

通过不同饥饿程度七星瓢虫雌、雄成虫对麦二叉蚜捕食作用的研究,得出：①饥饿不能改变七星瓢虫雌、雄成虫捕食作用的功能反应类型;②七星瓢虫雌、雄成虫间在各种饥饿条件下的捕食量差异均不显著;③七星瓢虫雌、雄成虫对麦二叉蚜的捕食量（Ｎａ）随着时间（ｔ）的变化,其模型分别是Ｎａ＝９０／１＋ｅ０．９４５３４－０．１５７４５ｔ和Ｎａ＝９０／１＋ｅ０．８７２８５－０．１２９８５ｔ;④七星瓢虫雌、雄成虫之间在２４ｈ内的捕食速度（Ｖ）差异不显著,其与时间段（ｘ）关系的模型分别为Ｖ＝８．３５５９ｘ－１．２４６０和Ｖ＝４．３４８７ｘ－０．５９６４。     

捕食性瓢虫的觅食行为

<正> 天敌昆虫的行为是决定其寄生或捕食效果的主要因子之一,其中觅食行为能直接影响它的控制效应。天敌昆虫觅食行为机制研究不够也是害虫生物防治效果尚不理想的一个重要原因。因此,全面研究天敌的觅食行为不仅是实际应用中选择有效天敌的关键,而且对于深入了解捕食者——猎物的相互关系,进一步完善已建立的各种功能反应数学模型,以及丰富行为生态学的理论与实践也十分必要。限于     

七星瓢虫成虫对绣线菊蚜捕食作用的室内测试

在实验室内测定了七星瓢虫成虫对苹果绣线菊蚜的捕食作用,结果表明,七星瓢虫成虫对绣线菊蚜密度的功能反应可用Holing-Ⅱ型圆盘方程较好地拟合,捕食作用在一定范围内随猎物密度的增加而加大;七星瓢虫成虫对绣线菊蚜的捕食作用率随着自身密度增加而减小,相互之间存在一定的干扰,自身密度的功能反应能用Hassell数学模型较好地反映。     

七星瓢虫成虫对枸杞木虱的捕食作用

为了测定七星瓢虫成虫对枸杞木虱4种虫态的捕食作用,分别在室内测定七星瓢虫的捕食功能反应、种内干扰、自身密度干扰、捕食偏好性以及在田间七星瓢虫对枸杞木虱的捕食效果.结果表明: 七星瓢虫对枸杞木虱的捕食功能反应符合Holling Ⅱ型方程,其中对卵的最大捕食量为112.6粒,对1～2龄若虫、3～5龄若虫、成虫的最大捕食量分别为536、415和113.9头;田间罩笼试验结果证明,七星瓢虫成虫在其生长周期30 d内能使枸杞木虱总虫口密度下降80.1%;七星瓢虫对1～2龄枸杞木虱若虫的搜寻效率参数a=0.9451,处理时间参数T_h=0.001865,整体优于卵、3～5龄若虫与成虫,且在每皿100头的猎物密度下七星瓢虫的最大捕食率能达80.2%,益害比参考值为1∶100.七星瓢虫对枸杞木虱的捕食作用受自身密度的影响显著大于种内干扰.在混合猎物密度为每皿100头下,七星瓢虫更偏好木虱成虫,在密度为每皿300头下,七星瓢虫更偏向于木虱若虫.表明七星瓢虫是很有控制潜力的捕食性天敌,人工释放七星瓢虫成虫可有效取食枸杞木虱初孵若虫,降低木虱为害.     

Tuned protection of aphids by ants against a predatory hoverfly

1. Aphid‐tending ants that feed on honeydew have evolved strategies against aphidophagous insects and tune their aggressive behaviour according to the level of danger for their trophobionts. Here we investigate how Lasius niger Linnaeus (Hymenoptera: Formicidae) ants react to different instars of Episyrphus balteatus De Geer (Diptera: Syrphidae) hoverflies which vary in their voracity and defensive abilities. 2. During pairwise encounters, early syrphid instars (eggs, L1, and L2 larvae) elicited lower aggression scores compared to third larval instars (L3), which was intensively bitten by ants. L3 tried to escape from ants by releasing a sticky and toxic secretion over biting ants that died or underwent severe morbidity. 3. In a standardised system including the host plant, aphid, tending ant, and hoverfly, the ability of ants to protect an Aphis fabae Scopoli (Hemiptera: Aphididae) colony was evaluated. Early E. balteatus instars placed onto the plant elicited no mobilisation of ants, which often removed the hoverfly successfully. Eggs and early instars appeared as the weak links for integrated pest management by hoverfly auxiliaries. 4. In contrast, L3 induced the number of ant patrollers to increase at a local scale without any further recruitment from inside the ant nest. L3 syrphids were quite efficient at gluing ants with defensive secretions and at resisting to removal attempts by ants. 5. While supporting the assumption that ants tune their defensive response to the aphidophagous predator, the present results also showed a lack of efficient protection of their trophobionts from the most voracious late syrphid instar.     

Plant penetration by pea aphids (Acyrthosiphon pisum) of different plant range

Plant penetration by the stylets of six clones of the pea aphid, Acyrthosiphon pisum, on Vicia faba (acceptable to all clones) and Pisum sativum (acceptable to 3/6 clones) was investigated by the DC electrical penetration graph technique. In a 10 h recording period, 93% of 144 aphids exhibited sustained feeding on phloem sap. Significant interclonal differences were observed for the incidence of potential drops (indicative of brief punctures of plant cells) and the duration of waveform E1 (insect salivation into a sieve element). In addition, the total duration of the sieve element phase and the duration of completed bouts of sustained feeding differed between the two test plants, in a fashion varying between clones. However, these differences could not be related to the acceptability of plants to the different aphid clones. The duration of the stylet pathway phase preceding the first sustained feeding on phloem sap did not vary significantly with either aphid clone or plant. It is concluded that the resistance of P. sativum to certain A. pisum clones does not arise from factors impeding either stylet penetration through the plant tissues or the maintenance of feeding from the sieve elements. It is proposed that host plant affiliation of A. pisum may be mediated primarily by specific olfactory or gustatory cues, before the aphid initiates stylet penetration of the plant.     

Predation by wasps on lepidopteran larvae in an Ozark forest canopy

ABSTRACT.

• 1 Predation by birds, crawling arthropods (ants, harvestmen, spiders), and social wasps (Vespula) spp. on introduced stocks of Heliothis virescens (Fabricius) larvae was investigated in a oak-hickory forest canopy in northwestern Arkansas (U.S.A.).
• 2 Wasps, Vespula maculifrons (Buysson) and V.squamosa (Drury), removed over 90% of the larvae. Repeated visits to a feeding site by the same marked wasps accounted for removal of either a single larva or all larvae. Larvae pinned (punctured) to artificial leaves were selected over 70% of the time by wasps when compared to attachments that did not puncture larvae; however, unpunctured larvae were taken.
• 3 Crawling arthropods accounted for low levels of predation, and birds did not appear to prey on larvae. Apparently wasps removed larvae rapidly and efficiently, thereby depleting the feeding sites before other predators discovered the larvae.
• 4 Although attaching larvae to artifical hickory leaves provided an easy method for placing larvae into the forest canopy, a lower percentage of larvae were removed from these leaves compared to natural hickory leaves. Moving feeding sites did not influence the number of larvae taken.

     

Predation on bats by Great Kiskadees

ABSTRACT.   Great Kiskadees ( Pitangus sulphuratus ) are found in a variety of habitats from Argentina north to the United States and are the most generalist tyrant flycatcher in both foraging behavior and food habits. These kiskadees are known to occasionally prey on small vertebrates, but, to our knowledge, bats have never been reported as a prey item. We observed a breeding pair of Great Kiskadees preying on bats ( Myotis spp.) at the field station Base de Estudos do Pantanal (BEP) in the southern Pantanal, Brazil. At BEP, there are fissures under the building's floor slabs that allow two species of bats, black myotis ( Myotis nigricans ) and silver-tipped myotis ( M. albescens ), to access internal galleries and use them as day roosts. We found that bats, insects, and fruits were the most common food items fed to nestlings by adult kiskadees. Bats ( N = 10) were captured when kiskadees landed on ground below a building, looked up through a fissure, and then reached through the fissure and captured a bat in their bill. On one occasion, a kiskadee flew from a perch and captured a bat in flight. Our observations provide further evidence of the opportunistic feeding behavior of Great Kiskadees.     

Predation rates of nemertean predators: the case of a rocky shore hoplonemertean feeding on amphipods

Estimates of the predation rates of benthic nemerteans are often based on observations of single individuals, and consequently they may not be representative for all members of a population of these predators. Herein we conducted controlled and repeatable laboratory experiments on the predation rate of the hoplonemertean Amphiporus nelsoni Sánchez 1973, which is common at exposed rocky shores along the central Chilean coast. During the austral fall (April, May 2000), nemerteans were observed in relatively high numbers crawling in the intertidal zone during early morning or late-afternoon low tides. When these nemerteans were offered living amphipods held by a forceps, they immediately attacked the amphipods and fed on them. In the laboratory experiments, nemerteans preferred the amphipod Hyale maroubrae Stebbing, 1899, which is also very common in the natural habitat of A. nelsoni. The nemerteans preyed to a higher extent on small males and non-ovigerous females than would have been expected from their abundance. We suggest that these (non-reproductive) stages of H. maroubrae are very mobile and therefore have a high likelihood of encounters with nemerteans. Predation rates reached maxima when nemerteans were provided prey densities of four or more of their preferred prey species, H. maroubrae, furthermore indicating that encounter rates with prey may affect predation rates. In long-term laboratory experiments, A. nelsoni consumed more amphipods during low tide conditions than during high tide conditions. Many nemerteans in the field prefer particular environmental conditions (e.g. nocturnal low tides), which restricts the time available for successful feeding. In the long-term experiment, predation rates of A. nelsoni never exceeded 0.5 amphipods nemertean^–1 d^–1. Maximum feeding events were 3 or 4 amphipods nemertean^–1 d^–1, but this only occurred during 10 out of a possible 2634 occasions. Nemerteans that had consumed 3 or 4 amphipods during 1 day, consumed substantially less prey during the following days. Towards the end of the long-term experiment, average predation rates decreased to 0.2 amphipods nemertean^–1 d^–1, corresponding to predation rates reported for other nemertean species (0.1–0.3 prey items nemertean^–1 d^–1). We suggest that predation rates from laboratory experiments represent maximum estimates that may not be directly transferable to field populations. Additionally, low predator–prey encounter rates with preferred prey in the field may further limit the predation impact of nemertean predators in natural habitats.     

自然天敌对苗蚜和伏蚜控制作用的定量分析

【目的】为了合理利用自然天敌,定量评价棉田自然天敌对苗蚜和伏蚜的控制作用。【方法】采用接虫罩笼法结合系统调查。【结果】发现苗蚜的主要自然天敌是龟纹瓢虫Propylaea japonica Thunberg和异色瓢虫Harmonia axyridis Pallas,大部分时间能够有效的控制苗蚜种群在防治指标以下,控害指数高达91%;伏蚜主要自然天敌是蜘蛛、草蛉和龟纹瓢虫,由于其种群数量太少,益害比低,对伏蚜控害指数始终低于20%,无法有效的控制伏蚜种群。【结论】结果提示,应根据苗蚜和伏蚜自然天敌控制作用不同,制定合理的保护利用自然天敌的策略。     

Predation on Cnidaria by vertebrates other than fishes

Records of predation by reptiles, birds and mammals on Cnidaria are reviewed.     

Larval and adult seed consumption affected by the degree of food specialization in Amara (Coleoptera: Carabidae)

Many carabid beetles (Coleoptera: Carabidae) are known to feed on plant seeds, but the level of specialization on this food differs. This is the first study in which seed consumption is assessed for all larval instars and adults of ground beetles. Three species of Amara with syntopic occurrence, Amara aenea (DeGeer), Amara familiaris (Duftschmid) and Amara similata (Gyllenhal), were examined. Larvae of all three instars and adults were fed seeds of Stellaria media (L.) Vill., Capsella bursa‐pastoris (L.) Med. and Taraxacum officinale Wick. ex Wigg. in a laboratory no‐choice experiment. In general, larvae, particularly the first instar, showed greater differences in seed consumption than the adults, although the latter showed similar but less marked pattern. Amara aenea consumed all offered seed diets in all life stages. All three larval instars of granivorous A. familiaris almost exclusively fed on seeds of S. media and the adults also ate significantly more of this than other seeds. Amara similata consumed mostly seeds of C. bursa‐pastoris in the first instar and adult stages, whereas the larvae of the later instars seemed to be unspecialized on particular seed diet. Differences in seed‐specific consumption between larval instars in granivorous carabids are reported for the first time. The results provide further support for the parallel evolution of various degrees of granivory in the genus Amara, which may ultimately facilitate species coexistence. The daily seed consumption by the larvae was comparable or (in case of the third instar) even higher than that by the adults. Hence, we suggest that larvae may be the important consumers of seed in the field and should not be forgotten when seed predation is assessed.     

The importance of honeydew as food for larvae of Chrysoperla carnea in the presence of aphids

Larvae of the common green lacewing Chrysoperla carnea are predacious and feed on a wide range of small, soft‐bodied arthropods. In addition to their feeding on prey arthropods to cover their nutritional requirements for growth and development, the consumption of non‐prey foods such as honeydew has been reported. It is commonly believed that these food supplements are primarily exploited by the larvae when prey is scarce or of low nutritional quality. Here, we assess whether C. carnea larvae also use honeydew when high‐quality aphid prey are readily available. In a choice experiment, the feeding behaviour of C. carnea larvae was observed in the presence of both aphids and honeydew. The larvae were starved, aphid‐fed, or honeydew‐fed prior to the experiment. The time spent feeding on honeydew compared with feeding on aphids was highest for starved larvae and lowest for honeydew‐fed larvae. Among the three treatments, the aphid‐fed larvae spent the most time resting and the least time searching. In an additional experiment food intake was assessed in terms of weight change when larvae were provided with an ad libitum supply of either aphids or honeydew. Larvae yielded a significant lower relative weight increase on honeydew compared with aphids. The reduced weight increase on honeydew was compensated when larvae were subsequently provided with aphids, but not when honeydew was provided again. This study showed that (i) prior honeydew feeding reduces overall aphid consumption, and (ii) larvae do consume honeydew even after they have been given ad libitum access to aphids. The fact that larvae of C. carnea still use honeydew as a food source in the presence of suitable prey underlines the importance of carbohydrates as foods.     

Predation of doggertooth on immature Pacific salmon

First occurrence of doggertooth predation on immature Pacific salmon is described from the Okhotsk Sea, off the Northern Kurile Islands. The possible significance of doggertooth for salmon abundance is discussed.