拟小食螨瓢虫成虫对朱砂叶螨的觅食行为

为明确拟小食螨瓢虫的觅食特性,揭示其觅食行为机制,本研究针对拟小食螨瓢虫成虫对朱砂叶螨不同虫态的取食选择、日取食节律以及觅食行为活动特点等进行了观察和阐述。结果表明,拟小食螨瓢虫成虫对朱砂叶螨卵、幼螨、若螨和成螨的取食嗜好性有显著差异,取食量分别为23.2、15.8、10.5和8.0头;瓢虫对成螨的平均日取食量为14.7头,其中在白天其觅食行为较频繁,9∶00-12∶00为捕食高峰期,此时段的平均取食量为4.0头成螨,夜间基本不取食;其觅食行为过程主要分为7个部分:搜索、捕捉、嚼食、梳理、展翅、排泄和静止。     

不同饥饿程度拟小食螨瓢虫对朱砂叶螨的捕食作用

为明确饥饿程度对拟小食螨瓢虫 Stethorus (Allosstethorus) parapauperculus 控害潜能的影响,本研究通过比较不同饥饿程度下拟小食螨瓢虫对朱砂叶螨 Tetranychus cinnabarinus 的功能反应和自身密度干扰效应,探讨不同饥饿程度拟小食螨瓢虫对朱砂叶螨的捕食作用。结果表明,饥饿程度对拟小食螨瓢虫朱砂叶螨的捕食量有明显的影响,瓢虫的取食量与朱砂叶螨的密度呈正相关,表现为饥饿48 h＞饥饿24 h＞未饥饿;拟小食螨瓢虫对各虫态朱砂叶螨的捕食作用均符合Holling Ⅱ模型。在一定空间范围内,拟小食螨瓢虫个体间存在竞争和相互干扰,Hassell Varley模型能较好地反映拟小食螨瓢虫在捕食各虫态朱砂叶螨时受自身密度的干扰情况。在同样饥饿状态下,随着瓢虫自身密度增加,捕食效率降低,干扰效应增大。     

拟小食螨瓢虫捕食六点始叶螨的初步观察

在室内以六点始叶螨Eotetranychus sexmaculatus(Riley)为猎物观察了拟小食螨瓢虫Stethorusparapauperculus Pang的发育历期、捕食量、捕食作用及干扰效应。研究结果表明:拟小食螨瓢虫取食六点始叶螨时完成一个世代需23.2 d,幼虫1～4龄的捕食量分别为9.5、14.5、19.5、64.2头六点始叶螨成螨;成虫期对六点始叶螨成螨的捕食量高达880.4头,拟小食螨瓢虫对六点始叶螨的捕食作用符合HollingⅡ方程,拟合的模型方程为Na=1.3843 N/(1+0.0231N),日均最大捕食量为43.29头;拟小食螨瓢虫的捕食率与个体间的干扰效应用Hassell-Varley(1959)模型拟合为E=0.4690P-0.5470。     

温度对拟小食螨瓢虫捕食皮氏叶螨成螨功能反应的影响

在5个温度(16℃、20℃、24℃、28℃和32℃)条件下,测定了拟小食螨瓢虫雌成虫对皮氏叶螨成螨的捕食功能反应。结果表明,在试验温度范围内,各温度下的功能反应均能用Holling圆盘方程(Ⅱ型)拟合,但各温度间功能反应的参数存在差异。以瞬时攻击率和捕食处理时间为评价指标,在16℃～28℃,拟小食螨瓢虫雌成虫对皮氏叶螨成螨的捕食效能随温度的上升而提高,28℃时达到最高,此时的瞬时攻击率和捕食处理时间分别为0.5899和0.0169d。温度上升至32℃时,捕食效能略为下降,此时的瞬时攻击率和捕食处理时间分别为0.5740和0.0184d,与28℃时的瞬时攻击率和捕食处理时间差异不显著。表明较高温度有利于拟小食螨瓢虫发挥对皮氏叶螨成螨的控制作用。在试验的密度和温度范围内,以三次多项方程描述了在不同猎物密度和温度组合下拟小食螨瓢虫雌成虫对皮氏叶螨成螨的捕食作用,以软件Surfer8.0生成了皮氏叶螨成螨密度和温度组合下的拟小食螨瓢虫雌成虫捕食量模拟值等值线图。同时,还对拟小食螨瓢虫在热带作物害虫生物防治中的应用潜力进行了讨论。     

2种瓢虫捕食烟粉虱行为的时间分配策略

【背景】沙巴拟刀角瓢虫和越南斧瓢虫是自东南亚地区引进的粉虱类害虫的优势捕食性天敌,然而其控制烟粉虱的有效性尚未明确。【方法】在室内研究了2种瓢虫幼虫捕食烟粉虱若虫时取食、爬行与休息等行为的时间分配,以及2种瓢虫幼虫和成虫在既定时间内对烟粉虱的取食时间和取食量。【结果】随着瓢虫幼虫龄期的增大,其取食烟粉虱低龄和高龄若虫的时间和休息时间均逐渐减少,而爬行寻找猎物的时间逐渐增多。沙巴拟刀角瓢虫幼虫取食烟粉虱各虫态的时间显著长于越南斧瓢虫幼虫,取食量也显著大于后者;而沙巴拟刀角瓢虫成虫取食烟粉虱的时间长于越南斧瓢虫成虫,但取食量明显低于后者。【结论与意义】2种瓢虫对烟粉虱都有较好的捕食作用,但其时间分配策略有所不同。因此,应根据田间烟粉虱的发生时期,选择合适的瓢虫进行释放。     

烟粉虱天敌沙巴拟刀角瓢虫与越南斧瓢虫的捕食行为比较

在实验室条件下研究了沙巴拟刀角瓢虫Serangiella sababensis Sasaji与越南斧瓢虫Axinoscymnus apioides Kuzne tsov and Ren对烟粉虱Bemisia tabaci(Genna dius)卵的捕食行为及各种行为的时间分配。2种瓢虫的捕食过程非常相似,大致可以分为搜寻、取食、清洁、静息、整翅和排泄6个部分。在整个捕食过程中,沙巴拟刀角瓢虫在饥饿状态下,其各行为所占的时间为爬行时间>取食时间>静息时间>清洁时间>猎物处置时间,而在非饥饿状态下,各行为所占的时间为爬行时间>静息时间>取食时间>清洁时间>猎物处置时间;对于越南斧瓢虫来讲,饥饿状态下各行为所占的时间比例为爬行时间>静息时间>取食时间>清洁时间>猎物处置时间,而在非饥饿状态,越南斧瓢虫用在取食方面的时间很少,仅长于处置猎物的时间。2种瓢虫相比,沙巴拟刀角瓢虫用在爬行和取食方面的时间要比越南斧瓢虫长,而用在静息和清洁方面的时间比越南斧瓢虫短。     

温度对拟小食螨瓢虫发育和繁殖的影响

拟小食螨瓢虫是热带地区香蕉、番木瓜、橡胶和木薯等作物上有害叶螨的重要天敌。在室内条件下,以皮氏叶螨Tetranychus piercei为食物,观察了不同温度(16℃,20℃,24℃,28℃,32℃)对拟小食螨瓢虫生长发育及繁殖的影响。结果表明:拟小食螨瓢虫卵、幼虫和蛹的历期在32℃下最短,分别为2.38,4.26和3.04 d;16℃时最长,分别为12.48,25.10和16.12 d,雌成虫寿命在16℃时长达142.53 d,而在32℃时为95.46 d。世代发育起点温度和有效积温分别为13.29℃和227.63日度。成虫产卵量在28℃最高,达595.49粒/雌,在16℃最低,为125.05粒/雌。内禀增长率(rm)在32℃达到最大(0.2063),而在16℃时最小(0.0342)。结果表明拟小食螨瓢虫有较好的高温耐受性,研究结果可为该瓢虫人工繁育的温度条件提供依据。     

异色飘虫成虫的限域搜索行为

对异色瓢虫雌、雄成虫在摄食前后的限域搜索行为的研究表明,摄食前后０~１５ｓ内搜索行为轨迹弯曲角度总和之间差异显著,摄食后显著大于摄食前,其搜索活动频繁地作方向变换,以此提高搜索效率;摄食前后０~１５ｓ、１５~３０ｓ、３０~４５ｓ内的各对应停点距离差异显著,摄自前各停点间距离显著大于摄食后;摄食前后０~１５ｓ、１５~３０ｓ、３０~４５ｓ搜索速度,摄自前是摄食后的４~１２倍,摄自前搜索速度变化很小,而摄食后离摄自的时间越长,搜索速度越快;摄食点到停点的直线距离,摄食前后之间差异显著,摄食前显著大于摄食后,若按面积范围比较,摄食前是摄食后的１１~６５倍．可以认为,异色瓢虫雌、雄成虫均具有限域搜索行为．     

深点食螨瓢虫和塔六点蓟马对朱砂叶螨的捕食作用

本文通过室内对深点食螨瓢虫Stethorus punctillum Weise和塔六点蓟马Scolothrips takahashii Priesener成虫捕食朱砂叶螨Tetranychus cinnabarinus(Boisduval)成螨的功能反应及种内干扰作用的研究,比较了2种天敌对朱砂叶螨的捕食能力。结果表明,深点食螨瓢虫和塔六点蓟马成虫对朱砂叶螨成螨的捕食功能反应均属HollingⅡ型,其模型分别为Na=0.7181N0/(1+0.0175N0)和Na=0.5168N0/(1+0.0136N0),日最大捕食量分别为41.11头和38.14头,处置时间分别为0.0243和0.0262d。深点食螨瓢虫和塔六点蓟马种内干扰模型分别为E=0.1916P-0.1805和E=0.1535P-0.4684。深点食螨瓢虫成虫对朱砂叶螨成螨的捕食能力强于塔六点蓟马。     

多异瓢虫食物消耗与利用与其猎物棉蚜的寄主植物种类相关

【目的】猎物质量和类型在捕食者食物选择、消耗及营养转化过程中起着重要作用,植物的营养质量影响植食者的营养质量,进而植食者作为捕食者猎物的营养质量。为进一步了解植物-猎物-捕食者三营养层的相互作用,研究了寄主植物对捕食者食物消耗与利用的影响。【方法】在室内评价了多异瓢虫Hippodamia variegata (Goeze) 4龄幼虫和雌成虫取食和利用 5种不同葫芦科植物上的棉蚜 Aphis gossypii Glover的效率。【结果】多异瓢虫4龄幼虫和成虫均对南瓜Cucurbita moschata var. melonaeformis上的蚜虫取食量最高,而对瓢葫芦Lagenaria siceraria var. gourda上的蚜虫取食量最低。4龄幼虫取食哈密瓜 Cucumis melo var. cantalupensis上的蚜虫时,其相对生长率、食物利用率和食物转化率均达到最大,而雌成虫在取食黄瓜Cucumis sativus和搅瓜Cucurbita pepo var. medullosa上的蚜虫时,其相对生长率不存在显著差异,在取食黄瓜、瓢葫芦和搅瓜上的蚜虫时,其食物利用率和食物转化率也不存在显著差异。因此,哈密瓜上的瓜蚜更适宜作为多异瓢虫4龄幼虫的猎物,而黄瓜、瓢葫芦和搅瓜上的瓜蚜更适宜作为成虫的猎物。【结论】寄主植物种类与多异瓢虫对棉蚜的捕食效率相关,该结论为进一步利用昆虫的食性对害虫进行控制奠定理论基础。     

The searching behaviour of Anthocoris confusus (Reuter) in relation to prey density and plant surface topography

• 1 The searching behaviour of A.confusus females was investigated in an artificial arena.
• 2 Females showed an increase in the frequency of turning movements following feeding and this concentrated search in a small area. As a result more prey were found in areas where prey distribution was clumped.
• 3 If no prey was encountered within 5–8 min the search track straightened out.
• 4 First and second instar nymphs searching on broad bean plants moved faster on the undersides of leaves which were the sites most likely to support aphid populations. A considerable proportion of available time was wasted in periods of inactivity.
• 5 It was concluded that while plant topography strongly influences search pattern, the underlying trend demonstrated in these experiments was of advantage to predators searching for colonial prey.

     

Ambulatory dispersal behavior ofNeoseiulus fallacis (Acarina: Phytoseiidae) in relation to prey density and temperature

Ambulatory dispersal behavior ofNeoseiulus fallacis (Garman) was studied in the laboratory to evaluate within-plant movement in relation to temperature and prey density. Adult femaleN. fallacis were confined in 2.5-cm-diameter arenas on the abaxial surface of excised corn leaves. Four temperatures (23, 28, 33, and 39° C) and prey densities ranging from 0 to 55 spider mite eggs per cm² were used. The walking paths of these mites were traced, digitized and used to calculate turning angles, walking speeds and turning rates. A computer simulation of walking behavior used this information to model mite ambulatory behavior and predict dispersal rates.Neoseiulus fallacis behavior while on whole corn leaves was quantified to verify the results of the simulation. The results showed thatN. fallacis will follow a leaf or arena edge (edge-walking) at all temperatures and prey densities. In addition, this behavior was used to the exclusion of the other types of behavior such as resting, and random-walk type search when prey egg density was less than 4 eggs per cm². The exclusion of edge-walking behavior from the model caused the model to underestimate substantially the dispersal rates leaves. These data suggest that there are at least two recognizable types of ambulatory search used byN. fallacis—the random-walk type, which is used when prey density is high (searching within prey patches), and the edge-walking behavior, which is used when prey density is low. This behavior allows the mite to travel rapidly from leaf to leaf in search of new prey patches.     

Functional groups in piscivorous fishes

Piscivory is a key ecological function in aquatic ecosystems, mediating energy flow within trophic networks. However, our understanding of the nature of piscivory is limited; we currently lack an empirical assessment of the dynamics of prey capture and how this differs between piscivores. We therefore conducted aquarium‐based performance experiments, to test the feeding abilities of 19 piscivorous fish species. We quantified their feeding morphology, striking, capturing, and processing behavior. We identify two major functional groups: grabbers and engulfers. Grabbers are characterized by horizontal, long‐distance strikes, capturing their prey tailfirst and subsequently processing their prey using their oral jaw teeth. Engulfers strike from short distances, from high angles above or below their prey, engulfing their prey and swallowing their prey whole. Based on a meta‐analysis of 2,209 published in situ predator–prey relationships in marine and freshwater aquatic environments, we show resource partitioning between grabbers and engulfers. Our results provide a functional classification for piscivorous fishes delineating patterns, which transcend habitats, that may help explain size structures in fish communities.     

Cowpea weevil flights to a point source of female sex pheromone: analyses of flight tracks at three wind speeds

Abstract.  Two-day-old male cowpea weevils, Callosobruchus maculatus, fly upwind to a point source of female sex pheromone at three wind speeds. All beetles initiating flight along the pheromone plume make contact with the pheromone source. Analysis of digitized flight tracks indicates that C. maculatus males respond similarly to moths tested at several wind speeds. Beetles' mean net upwind speeds and speeds along their track are similar ( P  > 0.05) across wind speeds, whereas airspeeds increase ( P <  0.01) with increasing wind speed. Beetles adjust their course angles to fly more directly upwind in higher wind speeds, whereas track angles are almost identical at each wind speed. The zigzag flight paths are generally narrow compared with most moth flight tracks and interturn distances are similar ( P  > 0.05) at the wind speeds employed. The frequency of these counterturns across the wind line is almost constant regardless of wind speed, and there is little variation between individuals. The upwind flight tracks are more directly upwind than those typically seen for male moths flying upwind toward sex pheromone sources. Male moths typically produce a bimodal distribution of track angles to the left and right of the windline, whereas C. maculatus males' track angles are centred about 0°. Preliminary examination of two other beetle species indicates that they fly upwind in a similar fashion.     

饲料蛋白质含量对黄粉虫生长繁殖及川硬皮肿腿蜂寄生能力的影响

【目的】筛选出适宜川硬皮肿腿蜂Scleroderma sichuanensis Xiao寄生的黄粉虫Tenebrio molitor饲料配方。【方法】用10种不同蛋白质含量的饲料饲喂黄粉虫,并观察各虫态生长繁殖情况,再用川硬皮肿腿蜂接种各配方黄粉虫蛹后置于培养箱中培养,5 d后计数雌蜂产卵量,并通过显著性分析、相关性分析及一元回归分析进行数据处理。【结果】各配方黄粉虫生长繁殖情况正常,指标间存在一定的显著性和相关性且与一元回归分析所得相关性一致。川硬皮肿腿蜂对黄粉虫蛹寄生率没有显著性,为86.25%~96.97%,表现出较高寄生率。寄生产卵量较高且蛋白质含量为14.09%和13.73%配方组显著高于其他配方组。【结论】黄粉虫饲料中蛋白质含量在14%(13.73%~14.09%)时川硬皮肿腿蜂寄生能力最强。     

Visual field of cultured striped trumpeter Latris lineata (Teleostei) larvae feeding on rotifer prey

The visual field of striped trumpeter Latris lineata larvae fed rotifer prey was determined from analysis of feeding behaviour in the horizontal plane. The visual field was forward and laterally directed, characterised by maximum reactive distances (distance at which the predator first detects and reacts to the prey) of 5.07 mm and 5.25 mm on days 13 and 17 post-hatching, respectively, 97% of mean larval length. This confirmed the predicted horizontal visual field, forward and laterally directed, derived from higher cone cell densities in the dorso-temporal and medial regions of the retina compared with ventral regions. The visual field of prey detection expanded laterally with ontogeny as a wider range of reactive angles was used by 17 day-old than 13 day-old larvae. Larvae displayed a saltatory searching pattern, periodically stopping to scan for prey throughout the visual field, and exhibited a side-to-side movement of the head as they approached and stopped, prior to striking at a detected prey item. Larvae on day 17 post-hatching terminated 35% of feeding sequences at the pre-strike position, at a mean distance from prey of 0.58 mm.     

You can run--or you can hide: optimal strategies for cryptic prey against pursuit predators

We consider the optimal behavior of a cryptic prey individualas it is approached by a predator searching for prey. Althoughthe predator has not yet discovered the prey, it has an increasinglikelihood of doing so as it gets closer to the prey. Further,the closer the predator is to the prey when it discovers it,the more likely the predator will be to capture the prey. Thesearguments suggest that the prey should flee before the predatordiscovers it. However, the act of fleeing will alert the predatorto the presence of the prey and trigger an attack that mightnot have occurred otherwise. We capture these conflicting outcomesin a mathematical model, which we then use to predict the optimalbehavior of the prey and predator. We argue that the optimalstrategy for the prey is either to run as soon as they detecta predator approaching or to only flee in response to havingbeen detected by the predator. Running as soon as the predatoris detected is associated with low predator search speeds, alow nonpredation cost to running, a large advantage to the preyin initiating chases rather than reacting, limited ability tospot the predator at distance, a high ability to spot prey bythe predator, and a high probability that chases will be successful.The optimal strategy for the predator depends on whether itscurrent trajectory is taking it closer to or further from theprey. In the latter case, the predator should attack immediatelyon discovering the prey; in the former case, it should delayits attack until it reaches the point on its current trajectorywhere distance to the prey is minimized.     

Difference in bacterial motion between forward and backward swimming caused by the wall effect

A bacterial cell that has a single polar flagellum alternately repeats forward swimming, in which the flagellum pushes the cell body, and backward swimming, in which the flagellum pulls the cell body. We have reported that the backward swimming speeds of Vibrio alginolyticus are on average greater than the forward swimming speeds. In this study, we quantitatively measured the shape of the trajectory as well as the swimming speed. The trajectory shape in the forward mode was almost straight, whereas that in the backward mode was curved. The same parameters were measured at different distances from a surface. The difference in the motion characteristics between swimming modes was significant when a cell swam near a surface. In contrast, the difference was indistinguishable when a cell swam >60 microm away from any surfaces. In addition, a cell in backward mode tended to stay near the surface longer than a cell in forward mode. This wall effect on the bacterial motion was independent of chemical modification of the glass surface. The macroscopic behavior is numerically simulated on the basis of experimental results and the significance of the phenomenon reported here is discussed.     

Limited attention: the constraint underlying search image

Recent models of predator search behavior integrate proximate neurobiological constraints with ultimate economic considerations.These models are based on two assumptions, which we have criticallyexamined in experiments with blue jays searching for artificialprey images presented on a computer monitor. We found, first,that when jays had to switch between searching for two distinctprey types, they showed no reduction in detection rates comparedto no-switching to no-switching conditions, and second, that when jays divided attention between searching for two prey typesat the same time, they had lower detection rates than whenthey focused attention on one prey type at a time. Our resultssuggest that limited attention strongly affects predator searchpatterns and diet choice, including the ubiquitous tendencyto form search images.