Foraging behavior of the coccinellid Nephus includens (Coleoptera: Coccinellidae) in response to Aphis gossypii (Hemiptera: Aphididae) with particular emphasis on larval parasitism

This study assessed the effect of parasitism of Nephus includens (Col.: Coccinellidae) larvae by Homalotylus flaminius (Hym.: Encyrtidae) on the predation rates of the predator on the cotton aphid, Aphis gossypii Glover (Hem.: Aphididae) by deriving functional responses for second- and fourth-instar predators at prey densities ranging from 10 to 80 aphids per arena. The relationship between the functional and numerical responses of adult females of N. includens also was determined for prey densities ranging from 10 to 140 aphids per arena. Predation rates of unparasitized and parasitized second-instar N. includens were both fit by a type II functional response model with parameters as follows: unparasitized (a = 0.0768 hours(-1) and T(h) = 0.975 h) and parasitized (a = 0.0787 hours(-1) and T(h) = 0.8823 hours). Predation rates of unparasitized and parasitized fourth-instar N. includens were fit by type III and II models, respectively, with the following parameters: unparasitized (b = 0.1702 hours(-1) and T(h) = 0.2369 hours) and parasitized (a = 0.038 h(-1) and T(h) = 0.539 h). The unparasitized fourth-instar was the most voracious stage, having the highest attack rate and lowest handling time. Considering these attributes, it would seem to be the most effective stage of this predator against A. gossypii. Adult female lady beetles (N. includens) showed a type III functional response and their numerical response increase to prey density was curvilinearly related to prey density, with the highest number of eggs being produced at highest prey densities. The maximum saturation level for both predation and egg production for adult females occurred at a prey density of 120 aphids. Thus, a ratio 1:120 (predator:prey) should be used when releasing this species for augmentative biological control. Release of either fourth-instar or adult stage N. includens should be minimized the potentially negative effect of parasitism by H. flaminius on early developmental stages, and hence increase its efficiency in biocontrol programs.     

贝氏小奥林螨连续饲养的草栖钝绥螨生命表参数和捕食能力

【目的】替代食物是饲养扩繁生物防治剂的重要组成部分,但连续单一食物可能会对天敌的存活、繁殖和捕食能力产生影响。本研究旨在明确以贝氏小奥林螨Oulenziella bakeri饲养的草栖钝绥螨Amblyseius herbicolus生长发育状况、繁殖和捕食能力。【方法】利用年龄-龄期两性生命表和捕食功能反应分别测定以贝氏小奥林螨为替代猎物的F₂, F₄和F₆代草栖钝绥螨生命表参数和对二斑叶螨Tetranychus urticae的捕食能力。【结果】在F₂, F₄和F₆代,草栖钝绥螨幼螨期随着饲养代数的增加逐渐延长,而雌成螨和雄成螨的寿命逐渐缩短,但卵、第1若螨和第2若螨的发育历期在各代之间无显著差异。在F₂, F₄和F₆代之间,草栖钝绥螨的存活率和种群参数无显著变化;种群参数中,不同饲养代数的内禀增长率(r)和周限增长率(λ)分别为0.19~0.20和1.21~1.22/d。F₂, F₄和F₆代草栖钝绥螨雌成螨对二斑叶螨若螨和雌成螨的捕食量无显著差异,其捕食功能反应均符合HollingⅡ型。【结论】以贝氏小奥林螨为替代猎物时,草栖钝绥螨能正常发育和繁殖,其种群数量呈增长趋势。本研究表明贝氏小奥林螨可以作为草栖钝绥螨人工饲养的潜在替代猎物。     

Functional and numerical responses of Propylea dissecta (Col., Coccinellidae)

The functional response of a ladybeetle, Propylea dissecta, to increasing density of aphid, Aphis gossypii, was of the curvilinear shape depicting Holling's type II response with fourth instar larva being the most voracious stage when compared with adult male and female. Prey handling time by different predatory stages decreased from 65.45 to 8.72 min with increase in prey density from 25 to 800. The predator aggregation and high prey density reduces the searching efficiency of the predator. Area of discovery was highest (1.4437) when a single predator was searching at minimum aphid density (25) and lowest (0.0366) when eight predators were searching at a constant aphid density (200). Mutual interference and quest constants were 0.75 and 0.40, respectively. The reproductive numerical response, in terms of eggs laid, increased curvilinearly with prey density and female laid 70.5 ± 5.55 eggs when exposed to highest prey density (400) and 12.3 ± 0.79 eggs at lowest prey density (10). The similar shapes of both functional and reproductive responses indicate that both responses are interlinked and function simultaneously.     

Vole fluctuations,red fox responses,predation on fawns,and roe deer dynamics in a temperate latitude

The alternative prey hypothesis predicts that predators respond both functionally and numerically (with a time lag) to fluctuations in the main prey abundance, which affects the survival of alternative prey. This pattern was found in northern Europe in the community formed by voles (Microtidae), red foxes (Vulpes vulpes) and roe deer (Capreolus capreolus). We studied the same predator—prey community in a temperate latitude where, according to the predation hypothesis, only the functional response of predators to changes in main prey availability should occur. In the years 1997–2007, in western Poland, we estimated the index of common vole (Microtus arvalis) abundance (burrow counts), the density of foxes (spotlight counts), the young production in foxes (young/adult ratio), the index of fox predation on fawns (prey remains near dens) as well as the reproduction index (fawn/female ratio) and density of roe deer (total counts). The vole abundance fluctuated considerably, the young production in foxes did not correlate with the main prey availability, but the density of foxes showed direct numerical response. The index of fox predation on fawns decreased with the vole abundance and negatively affected the fawn/female ratio in roe deer. Thus, the relationships between voles and foxes were not fully consistent with the predation hypothesis. The direct numerical response of foxes should tend to stabilize this predator—prey community. It is suggested, however, that responses showed by vole-eating predators in temperate latitudes may sometimes affect their alternative prey, including animals with unfavourable conservation status.     

Predatory Potential of Euseius alatus (Phytoseiidae) on Different Life Stages of Oligonychus ilicis (Tetranychidae) on Coffee Leaves Under Laboratory Conditions

This study evaluated the predatory capacity of Euseius alatus (DeLeon) as a biological control agent of the pest mite Oligonychus ilicis (McGregor) on coffee leaves under laboratory conditions, using arenas containing 25 O. ilicis per coffee (Coffea arabica) leaf to one specimen of each stage of the predator mite. The functional response and oviposition rate of adult females of E. alatus were evaluated on coffee leaf arenas and offered from 1 to 125 immature stages of O. ilicis per arena. The number of preys killed and the number of eggs laid by the predator were evaluated every 24 h during 8 days. The preys consumed were daily replaced. Male and female adults of E. alatus were the most efficient in killing all developmental stages of O. ilicis. Larvae and nymphs of O. ilicis were the most consumed by all stages of the predatory mite. The functional response and oviposition rates of E. alatus increased as the prey density increased, with a positive and highly significant correlation. Regression analysis suggested a type II functional response, with a maximum predation of 22 O. ilicis/arena and a maximum oviposition rate of 1.7 eggs/day at a density of 70 O. ilicis/arena.     

竹盲走螨对竹裂爪螨的捕食功能

在实验室模拟条件下,系统研究了竹盲走螨对竹裂爪螨的控制作用.结果表明,在25±0.5 ℃条件下,竹盲走螨对竹裂爪螨各螨态的功能反应均属HollingⅡ型.在同一温度条件下,雌竹盲走螨成螨对竹裂爪螨各螨态的处置时间依次为卵<幼螨<前若螨<后若螨<雌成螨.竹裂爪螨卵、幼螨、若螨、雌成螨共存时,竹盲走螨嗜食卵、幼螨和前若螨（Q>1）,但其对卵与幼螨及幼螨与前若螨无偏嗜现象.当竹裂爪螨密度低于9头时,竹盲走螨的产卵量随密度增加而增加;9～15头时,其日平均产卵量保持在每雌2粒左右;超过15头以后,产卵量反而下降,说明猎物密度过高对捕食者生存、繁殖存在干扰作用.     

小黑瓢虫与两种猎物作用系统研究:选择捕食作用

研究了小黑瓢虫与烟粉虱及红蜘蛛两种猎物作用系统中 ,小黑瓢虫雌成虫对两种猎物卵的选择捕食作用。结果表明 :当两种猎物共存时 ,小黑瓢虫雌成虫对烟粉虱卵在低密度下不表现喜好性 ,而在中等密度和高密度下表现正喜好性 ,对红蜘蛛卵在各密度下均不表现喜好性。对烟粉虱卵的转换效应会由于总猎物密度的不同而呈现不同的效应 ,即在低密度 (15 0粒 )时无转换行为 ,在中等密度 (30 0粒 )时有负转换行为 ,在高密度 (6 0 0粒 )时有正转换行为。而对红蜘蛛卵则在各总猎物密度下均呈现负转换效应。同时组建了两种猎物共存时 ,小黑瓢虫雌成虫对猎物的总捕食作用方程及对每一种猎物类型的捕食作用方程 ,分析了两种猎物共存时 ,小黑瓢虫雌成虫对各猎物寻找效应的变化情况。     

Effect of tomato leaf hairiness on functional and numerical response of Neoseiulus californicus (Acari: Phytoseiidae)

The objective of this study was to determine whether differences in hairiness of tomato plants affect the functional and numerical response of the predator Neoseiulus californicus McGregor attacking the two-spotted spider mite, Tetranychus urticae Koch. Two tomato hybrids with different density of glandular hairs were used. The functional response was measured by offering eggs and adults of T urticae at densities ranging from 4 to 64 items per tomato leaflet (surface ca. 6.3 cm2); eggs were offered to predator protonymphs and deutonymphs, adult spider mites to adult predators. The number of spider mites eaten as a function of initial density was fitted to the disc equation. Predator densities were regressed against initial prey densities to analyze the numerical response. The number of eggs and adults of T. urticae eaten by N. californicus was extremely low in both hybrids. The nymphal stage of N. californicus and prey density had a significant effect on the number of T urticae eggs eaten by the predator, while hybrid had no effect. The functional response fitted reasonably well to the Holling model. The handling time (Th) and the attack rate (a) were very similar among the two hybrids. The numerical response indicated that the absolute density of predators increased with changes in spider mite densities but the relative predator/prey density decreased in both hybrids. Tomato hairiness prevented N. californicus from exhibiting a strong numerical response and the predator functional response was much lower than observed in other host plants and other phytoseiids. This result shows the need to consider plant attributes as an essential and interactive component of biological control practices.     

Reproductive performance of the mite Brevipalpus phoenicis (Geijskes, 1939) on citrus and coffee, using life table parameters.

The flat-mite Brevipalpus phoenicis (Geijskes, 1939) (Acari: Tenuipalpidae) is considered important in citrus (Citrus spp.) and coffee plants (Coffea spp.) in Brazil, and is known as the leprosis and coffee ring spot mite, as being a vector of the Citrus Leprosis Rhabdovirus - CitLV and Coffee Ring Spot Virus - CoRSV. The objective of this work is to find out about the reproductive success of B. phoenicis on citric fruits and coffee leaves by fertility life table parameters and its biology. The experiments were carried out in laboratory conditions at 25 +/- 2 degrees C, 70 +/- 10% of relative humidity and 14 h of photophase. The lengths of embryonic and post-embryonic periods were different due to the host where the mite was reared. B. phoenicis showed better development and higher survival and fecundity in citric fruits than coffee leaves. The intrinsic rate of the population increase (r(m)) was 0.128 and 0.090 - females/female/day on citric fruits and coffee leaves, respectively. The citric fruits were more appropriate for the development of B. phoenicis than coffee leaves.     

The demographic and life‐history costs of fear: Trait‐mediated effects of threat of predation on Aedes triseriatus

相似文献   

PREDATION OF THE LADYBEETLE CHILOCORUS KUWANAE ON THE SCALE UNASPIS YANONENSIS

Abstract The prey consumption of ovipositing female adults of the ladybeetle Chilocorus kuwanae on the scale Unaspis yanonensis was found to be significantly greater than that of the male adults. At 25°C one female adult ladybeetle, on average, would consume 42. 7 female scale adult per day while one male adult only destroyed 22. 3 female scale adults. However, after a deprivation of the prey for 48 h, this difference was eliminated. A C. kuwanae female adult had to prey on at least 15 U. vanonensis female adults in order to lay eggs. The funcional responses of the beetle adults to densities of different stages of the scale followed Holling's type 1. The functional responses to female scale adults indicated that the maximum prey consumption went up with the increase in temperature from 16°C to 35°C, and dropped sharply at 37°C. However, temperature did not alter the type of the functional response. Rased on the predation of C. kuwanae adults on U. yanonensis female adults, the minimum critical, optimal and maximum critical temperatures for their attack were estimated to be 10. 6°C, 31. 5°C and 38. 2°C respectively. The increase in predation space or in predator density could result in a reduction in the attack rat-e, but with the increase of predator density, the effect of predation space became much smaller. C. kuwanae adults preferred male pupae to other stages of the scale, and their preference for various stages of the prey was in the order of male pupae, 2nd-instar male nymphs, 2nd-instar female nymphs, adult females and kinstar nymphs.     

Functional responses of Iphiseius degenerans and Neoseiulus teke (Acari: Phytoseiidae) to changes in the density of the cassava green mite, Mononychellus tanajoa (Acari: Tetranychidae)

The functional responses of protonymph and adult female Iphiseius degenerans and Neoseiulus teke to increasing density of three stages of their prey, the cassava green mite (CGM), Mononychellus tanajoa, were studied on excised cassava leaf discs under laboratory conditions. The responses obtained were predominantly sigmoid type III curves with the highest plateau when both stages of I. degenerans and N. teke were preying on CGM eggs. In all cases, the predation rate of the former species exceeded that of the latter. The empirical data were fitted by four different models. From the models, the attack coefficient (a) and handling time (T _h) were estimated. For a given predator stage (protonymph or adult female), the predator's attack coefficient declines and handling time increases as the prey gets larger. For a given prey stage, the predator's attack coefficient increases and handling time decreases as the predator stage becomes larger.     

Functional response of Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae) to Bemisia tabaci (Gennadius) on tomato leaves

Bemisia tabaci (Gennadius) is an important invasive pest of vegetables and other horticultural plants worldwide. In this study, the functional response of Neoseiulus cucumeris (Oudemans) to different stages of immature B. tabaci was evaluated under laboratory conditions. Predation experiments were conducted on tomato leaf discs (2.5?cm diameter) over a 24-h period at 26?±?1°C and 65?±?5% relative humidity with a L16:D8 photoperiod. The prey densities ranged from 5 to 90 immature stages (eggs and first- to fourth-instar nymphs) of B. tabaci per leaf disc. The results showed that the egg stage of B. tabaci was the most susceptible prey stage and that the mated female adult mite (3-day-old) was a more effective predator than the male adult mite. The functional response of adult N. cucumeris followed a Type II trend curve as shown in a logistic regression model. Adult N. cucumeris exhibited different predation tendencies towards prey in different stages of immaturity. The daily maximum number of eggs, first-, second- and third-instar nymphs of B. tabaci killed by a single female over a 24-h period (26?±?1°C, 65?±?5% RH and L16:D8 photoperiod) were 8.5, 5.2, 3.0 and 2.1, respectively, whereas the number killed by a single male was 6.0, 4.0, 2.3 and 1.8, respectively. The results of this study could help determine an effective B. tabaci biocontrol measure that employs a natural predator.     

Predation,oviposition and longevity of the predacious mite,Agistemus exsertus Gonzalez at different prey densities of Tetranychus urticae Koch (Acari: Stigmaeidae,Tetranychidae)

The relation between some biological aspects of the predatory mite, Agistemus exsertus Gonzalez and nymph densities of Tetranychus urticae Koch was studied in the laboratory. Predation and oviposition of A. exsertus showed Holling's Type II functional and numerical responses to changes in prey density. The total predation by A. exsertus females initially averaged 79.42 nymphs/female at 2 prey nymphs/day, significantly increased to a maximum average of 208.92 nymphs/female at 10 nymphs/day and gradually decreased to 90.92 nymphs/female at 30 prey items/day. Similarly, the predator significantly deposited total averages of 14.75, 76.42 and 34.33 eggs/female at 2, 10 and 30 nymph densities/day, respectively. The preoviposition and oviposition periods as well as longevity of A. exsertus significantly shortened with increasing prey densities.     

多异瓢虫成虫对枸杞木虱的捕食作用

【目的】为了测定多异瓢虫Hippodamia variegata(Goeze)成虫对枸杞木虱Paratrioza sinica Yang&Li的捕食作用。【方法】在室内测定了多异瓢虫的捕食功能反应、种内干扰、自身密度干扰、捕食偏好性,并通过罩笼试验研究多异瓢虫在田间对枸杞木虱的捕食效果。【结果】结果表明,多异瓢虫对枸杞木虱的捕食功能反应符合HollingⅡ型方程,对卵、1~2龄若虫、3~5龄若虫以及成虫的最大捕食量分别为80.4粒、410.0头、350.8头和102.5头。田间罩笼试验结果证明,在多异瓢虫成虫生长周期30 d内能使枸杞木虱总虫口密度下降85.4%;多异瓢虫对枸杞木虱成虫的搜寻效率a=0.8252为4种木虱虫态最佳,而对枸杞木虱卵处理时间Th=0.002283为4种木虱虫态中最佳;在100头/皿的猎物密度下多异瓢虫均能展现其最大捕食率,益害比参考值为1∶100。多异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100头/皿混合猎物密度下,多异瓢虫更偏好木虱成虫,在300头/皿下,多异瓢虫更偏向于木虱若虫。【结论】研究表明,多异瓢虫是具有控制潜力的捕食性天敌,人工释放多异瓢虫成虫可有效防治枸杞木虱。     

Modeling changes in predator functional response to prey across spatial scales

Extrapolation of predator functional responses from laboratory observations to the field is often necessary to predict predation rates and predator-prey dynamics at spatial and temporal scales that are difficult to observe directly. We use a spatially explicit individual-based model to explore mechanisms behind changes in functional responses when the scale of observation is increased. Model parameters were estimated from a predator-prey system consisting of the predator Delphastus catalinae (Coleoptera: Coccinellidae) and Bemisia tabaci biotype B (Hemiptera: Aleyrodidae) on tomato plants. The model explicitly incorporates prey and predator distributions within single plants, the search behavior of predators within plants, and the functional response to prey at the smallest scale of interaction (within leaflets) observed in the laboratory. Validation revealed that the model is useful in scaling up from laboratory observations to predation in whole tomato plants of varying sizes. Comparing predicted predation at the leaflet scale, as observed in laboratory experiments, with predicted predation on whole plants revealed that the predator functional response switches from type II within leaflets to type III within whole plants. We found that the magnitude of predation rates and the type of functional response at the whole plant scale are modulated by (1) the degree of alignment between predator and prey distributions and (2) predator foraging behavior, particularly the effect of area-concentrated search within plants when prey population density is relatively low. The experimental and modeling techniques we present could be applied to other systems in which active predators prey upon sessile or slow-moving species.     

Perspectives for mass rearing of Iphiseiodes zuluagai Denmark & Muma (Acari: Phytoseiidae)

Iphiseiodes zuluagai Denmark & Muma is an important predator of Brevipalpus phoenicis (Geijskes) on citrus in Brazil. The suitability of Tyrophagus putrescentiae (Schrank) as a food source of I. zuluagai in laboratory rearing was investigated at 25.5 +/- 0.5 masculineC, 88 +/- 7% RU and photophase of 12h. Initially, levels of oviposition of the predator fed on eggs were evaluated, as well as the dead or live post-embryonic stages of T. putrescentiae, in a period of 10 days. The daily oviposition rate was 1.3 egg per female when they were fed on eggs on T. putrescentiae, 0.7 egg per female when they were fed on dead post embryonic stages and about 0.3 egg per female when they were fed on live post-embryonic stages. Later, the life table of I. zuluagai was constructed, when eggs of T. putrescentiae were offered to the predators as prey. The immature stages were observed every 8h, to determine the corresponding durations. In the adult phase, the mites were observed every 24h, to determine the reproductive parameters. The intrinsic rate of natural increase (r m) was 0.11 female/ female/day; resulting in a finite rate of increase of 1.11 (l). The net reproductive rate (R0) was 7.1 females/generation, with a mean generation time (T) 18.6 days. The results show that T. putrescentiae is a favorable food source for the development of I. zuluagai.     

Predator‐mediated interactions between preferred,alternative and incidental prey in the arctic tundra

Apparent competition between prey is hypothesized to occur more frequently in environments with low densities of preferred prey, where predators are forced to forage for multiple prey items. In the arctic tundra, numerical and functional responses of predators to preferred prey (lemmings) affect the predation pressure on alternative prey (goose eggs) and predators aggregate in areas of high alternative prey density. Therefore, we hypothesized that predation risk on incidental prey (shorebird eggs) would increase in patches of high goose nest density when lemmings were scarce. To test this hypothesis, we measured predation risk on artificial shorebird nests in quadrats varying in goose nest density on Bylot Island (Nunavut, Canada) across three summers with variable lemming abundance. Predation risk on artificial shorebird nests was positively related to goose nest density, and this relationship was strongest at low lemming abundance when predation risk increased by 600% as goose nest density increased from 0 to 12 nests ha^?1. Camera monitoring showed that activity of arctic foxes, the most important predator, increased with goose nest density. Our data support our incidental prey hypothesis; when preferred prey decrease in abundance, predator mediated apparent competition via aggregative response occurs between the alternative and incidental prey items.     

Numerical and dietary responses of a predator community in a temperate zone of Europe

The generalist predation hypothesis predicts that the functional responses of generalist predator species should be quicker than those of specialist predators and have a regulating effect on vole populations. New interpretations of their role in temperate ecosystems have, however, reactivated a debate suggesting generalist predators may have a destabilizing effect under certain conditions (e.g. landscape homogeneity, low prey diversity, temporary dominance of 1 prey species associated with a high degree of dietary specialization). We studied a rich predator community dominated by generalist carnivores ( Martes spp., Vulpes vulpes, Felis catus ) over a 6 yr period in farmland and woodland in France. The most frequent prey were small rodents (mostly Microtus arvalis , a grassland species, and Apodemus spp., a woodland species). Alternative prey were diverse and dominated by lagomorphs ( Oryctolagus cuniculus, Lepus europeus ). We detected a numerical response among specialist carnivores but not among generalist predators. The dietary responses of generalist predators were fairly complex and most often dependent on variation in density of at least 1 prey species. These results support the generalist predation hypothesis. We document a switch to alternative prey, an increase of diet diversity, and a decrease of diet overlap between small and medium-sized generalists during the low density phase of M. arvalis . In this ecosystem, the high density phases of small mammal species are synchronous and cause a temporary specializing of several generalist predator species. This rapid functional response may indicate the predominant role of generalists in low amplitude population cycles of voles observed in some temperate areas.     

The effect of prey morphology on the feeding behaviour and population growth of the predatory rotifer Asplanchna sieboldi: a case study using five species of Brachionus (Rotifera)

1. We investigated the numerical response, functional response and prey preference of Asplanchna sieboldi to five different prey brachionids. We also analysed the feeding behaviour of the predator in terms of encounters, attacks, capture and prey ingested per unit time. 2. The five prey species (Brachionus havanaensis, B. rubens, B. patulus, B. macracanthus and B. calyciflorus) differed in their body size and spine length. 3. The population growth rates of A. sieboldi ranged from 0.074 ± 0.03 to 0.431 ± 0.02 depending on prey type and density. There was a significant impact of the spine length rather than body size per se on the population growth rates of the predator. 4. The maximum number of prey consumed depended on both body size and spine length. In the functional response analyses, the plateau was reached at a prey density of 4–8 ind. mL^?1. 5. There was a significant impact of prey density on the prey preference of the predator.