Suitable Prey Research Articles

Ecology and Natural History of the Easternmost Native Lizard Species in South America, Trachylepis atlantica (Scincidae), from the Fernando de Noronha Archipelago, Brazil

We studied the ecology of Trachylepis atlantica, the easternmost native lizard species in South America, endemic to the Fernando de Noronha archipelago, approximately 350 km off the northeastern coast of Brazil. Activity of this species extended from dawn to dusk, with a peak from 1200–1400 h. Mean body temperature of active T. atlantica was 32.2 ± 2.9°C and was significantly related to both air and substrate temperatures. Trachylepis atlantica used most types of available substrates in the area but was found most frequently (72.5% of observations) on rocks and normally used perches up to 80 cm high. There was sexual dimorphism in body size, with males larger than females. Trachylepis atlantica had an omnivorous diet, with plant material comprising 77% of the volume ingested and being present in 67% of stomachs with food. Formicidae and insect larvae were the main animal items in the diet. Mean prey volume (6.9 ± 5.3 mm3) was small compared to other related species. This, coupled with the high plant consumption, suggests that local availability of suitable prey may be limited, as expected for small islands in general.

Contribution of phagotrophy versus autotrophy to Prymnesium parvum growth under nitrogen and phosphorus sufficiency and deficiency

Laboratory experiments were conducted to test the effects of nitrogen (N) and phosphorus (P) sufficiency and deficiency on mixotrophy in Prymnesium parvum (Haptophyta). P. parvum was grown with and without algal prey ( Rhodomonas salina) and observed for 120 h. Detection and enumeration of cells containing food vacuoles with prey (i.e. phagotrophy) was based on flow cytometric detection of fluorescence of an acidotropic probe. Overall, the presence of R. salina increased phagotrophy in P. parvum suggesting that, at least in this strain of P. parvum, the presence of suitable prey can stimulate phagotrophic behavior in P. parvum. Feeding frequency (the percentage of P. parvum cells containing food vacuoles in a given time) was significantly higher under N and P deficiency than in the nutrient-sufficient treatments. A nutrient budget constructed from the data indicated that ingestion of organic matter (OM) supplied with 78 ± 7% of the N (3.9 ± 0.3 μM) incorporated by P. parvum in the N-deficient treatment, and 45 ± 9% of the P (0.3 ± 0 μM) acquired in the P-deficient cultures. Even under nutrient sufficiency, ingestion of OM was estimated to have supplied 43 ± 16% of the N and 48 ± 16% of the P incorporated into P. parvum cells. Phagotrophy was observed even in the NP-sufficient cultures (non-axenic mixed and monocultures), although P. parvum cells did not lose their photosynthetic capability, suggesting that phagotrophy is probably a permanent nutritional adaptation to this species. The ingestion of organic nutrients played an important role in P. parvum growth, being a reliable source of nutrition for P. parvum inorganic nutrient limitation, and could explain its capabilities to form persistent blooms.

Coupling osteological development of the feeding apparatus with feeding performance in common snook, Centropomus undecimalis, larvae: Identifying morphological constraints to feeding

Identifying bottlenecks to feeding in marine finfish larvae is becoming a dominant theme as commercially important fish stocks collapse worldwide. The transition from endogenous yolk reserves to feeding exogenously is perhaps the largest constraint to developing aquaculture technologies in closed systems. Mass mortality during early larval development is generally attributed to a lack of suitable prey during the first feeding stage, however, empirical evidence identifying a causal link between morphology and performance remains scarce. In this study, we examined the link between osteological development of the feeding apparatus and feeding performance, expressed as (1) the median number of prey consumed by larvae and (2) the median size of prey consumed by larvae, during larval development of the common snook, Centropomus undecimalis. Cluster analysis, nMDS, and SIMPER analysis allowed us to identify functional intervals of the feeding apparatus through larval development. Results revealed that first feeding larvae exhibited rudimentary skeletal elements and selected only one or two of the prey types available relative to older larvae, which included more and larger prey types in their diet. Upon complete formation of the hyoid apparatus, around 8 dph, a dietary shift to rotifers was observed suggesting that high rates of mortality observed in closed culture systems may be attributed to the absence of a suitable small, non-elusive food organism during the first feeding stage. First feeding larvae exhibit a poorly developed feeding apparatus that may constrain their ability to consume elusive prey as an initial diet. Based on the association between stage-specific characteristics of the feeding apparatus and corresponding stage-specific metrics of feeding performance established in this study, we propose a stage-specific feeding-management scheme for snook hatchery aquaculture.

Suitability of the tomato borer Tuta absoluta as prey for Macrolophus pygmaeus and Nesidiocoris tenuis

AbstractThe tomato borer, Tuta absoluta (Meyrick) (Lep.: Gelechiidae), is an important tomato pest native to South America, which appeared in eastern Spain at the end of 2006. Prey suitability of T. absoluta eggs and larval instars was examined under laboratory conditions to evaluate whether two indigenous predators, Macrolophus pygmaeus (Rambur) and Nesidiocoris tenuis Reuter (Hem.: Miridae), can adapt to this invasive pest. Both predators preyed actively on T. absoluta eggs and all larval stages, although they preferred first‐instar larvae. Our results demonstrate that both mirids can adapt to this invasive pest, contributing to their value as biological control agents in tomato crops.

Typhlodromips swirskii (Acari: Phytoseiidae): A Predator of Eriophyid and Tetranychid Mango Mites in Egypt

The predacious mite Typhlodromips swirskii (Athias-Henriot) successfully developed to the adult stage when fed on themotile stages of the mango bud mite Aceria mangiferae Sayed, the mango rust mite Metaculus mangiferae (Attiah), theleaf coating mite Cisaberoptus kenyae Keifer and nymphs of the mango red mite Oligonychus mangiferus (Rahman andSabra) in the laboratory at different temperatures and relative humidities. The increase of temperature degree anddecrease relative humidity from 25°C and 60% R.H. to 30°C & 55%R.H. and 35 °C & 50 %R.H. shorteneddevelopment and increased reproduction and prey consumption. Different eriophyid prey species promoted fasterdevelopment of the predator compared to feeding on the tetranychid nymphs. The rate of egg laying (2.62, 2.23, 2.35and 1.83 eggs/♀/day) was recorded at the highest temperatures and lowest R.H., while the minimum reproduction (1.92,1.72, 1.62 and 1.20 eggs/♀/day) was noted at the lowest temperature and highest R.H. when fed on the fouraforementioned prey species, respectively. Life table parameters indicated that feeding T. swirskii on A. mangiferae ledto the highest reproduction rate (rm = 0.216 and 0.157 females/female/day), while feeding on O. mangiferus gave thelowest reproduction rate (rm= 0.183 and 0.133) nymphs at 35°C and 50%R.H. and 25°C and 60% R.H., respectively.The adult predatory female consumed an average of 117.8 A. mangiferare, 114.18 C kenyae, 94.4 M. mangiferae motilestages and 14.58 O. mangiferus nymphs at 35°C and 50% R.H./day, while it devoured 102.8, 96.59, 90.44 and 12.35individuals, respectively at 25°C and 60% R.H. The three eriophyid mango mites, particularly A. mangiferae, proved tobe suitable prey for T. swirskii, as a facultative predator, compared to the tetranychid mango mite.

Propagation, Synchrony, and Impact of Introduced and Native <I>Laricobius</I> spp. (Coleoptera: Derodontidae) on Hemlock Woolly Adelgid in Virginia

Synchrony and impact of the predators Laricobius nigrinus Fender and Laricobius rubidus LeConte, on hemlock woolly adelgid, Adelges tsugae Annand, were studied in an eastern hemlock field insectary in Virginia. First, a field insectary for propagation of the introduced L. nigrinus was established by planting hemlocks in 2001, infesting them with hemlock woolly adelgid in 2002 and 2003, followed by releasing 258 L. nigrinus in 2003. Initial sampling showed that the native L. rubidus was present in the area. Hemlock woolly adelgid and both Laricobius species populations increased annually, from which 305 F3 L. nigrinus adults were collected and redistributed to forests in 2007. Second, the phenology of hemlock woolly adelgid and Laricobius spp. life cycles were monitored in 2005 and 2006. Adult L. nigrinus (F2) and L. rubidus were active on hemlock from fall through mid-spring and overlapped with second-instar sistentes nymphs through progredientes eggs. The predators' eggs were oviposited and larvae developed (i.e., F3 L. nigrinus) from late winter to mid-spring on progredientes eggs, indicating synchrony with suitable prey life stages. Third, a predator exclusion experiment was used to examine the relationships between the predators and prey in 2005 and 2006. When exposed to L. nigrinus (F2 adults and F3 larvae) and L. rubidus, hemlock woolly adelgid survival and ovisac density were lower and ovisac disturbance was higher than hemlock woolly adelgid protected in cages. The establishment and production of L. nigrinus at a field insectary, synchronization with, and impacts on hemlock woolly adelgid after a small release 2 yr earlier makes it an important potential biological control agent of hemlock woolly adelgid.

Predation by <I>Podisus maculiventris</I> (Say) (Hemiptera: Pentatomidae) on Viburnum Leaf Beetle, <I>Pyrrhalta viburni</I> (Paykull) (Coleoptera: Chrysomelidae), Under Laboratory and Field Conditions

To evaluate the potential of Podisus maculiventris (Say) (Heteroptera: Pentatomidae) as a biological control agent against viburnum leaf beetle, Pyrrhalta viburni (Paykull) (Coleoptera: Chrysomelidae), laboratory trials were conducted to measure prey consumption of P. maculiventris over nymphal development. Field trials tested the impact of augmentative releases of P. maculiventris nymphs on populations of P. viburni, using both open shrubs and caged branches of Viburnum trilobum. In the laboratory, P. maculiventris nymphs successfully developed while preying on P. viburni larvae and adults. Each nymph consumed an average of 100.6 larvae or 16.9 adults. Immature development duration was comparable between nymphs feeding on P. viburni adults and those given Galleria mellonella (L.) (Lepidoptera: Pyralidae) larvae as prey. In field trials, inundative releases of 30 P. maculiventris nymphs on naturally infested V. trilobum shrubs significantly reduced pest defoliation on shrubs infested with < 3,000 larvae but had no effect on shrubs with heavier infestations. On caged branches, individual nymphs successfully developed when feeding only on P. viburni larvae. These results show that P. viburni larvae and adults are suitable prey for P. maculiventris and this predator could potentially be developed as a biological control agent against P. viburni.

Predation byPodisus maculiventris(Say) (Hemiptera: Pentatomidae) on Viburnum Leaf Beetle,Pyrrhalta viburni(Paykull) (Coleoptera: Chrysomelidae), Under Laboratory and Field Conditions

To evaluate the potential of Podisus maculiventris (Say) (Heteroptera: Pentatomidae) as a biological control agent against viburnum leaf beetle, Pyrrhalta viburni (Paykull) (Coleoptera: Chrysomelidae), laboratory trials were conducted to measure prey consumption of P. maculiventris over nymphal development. Field trials tested the impact of augmentative releases of P. maculiventris nymphs on populations of P. viburni, using both open shrubs and caged branches of Viburnum trilobum. In the laboratory, P. maculiventris nymphs successfully developed while preying on P. viburni larvae and adults. Each nymph consumed an average of 100.6 larvae or 16.9 adults. Immature development duration was comparable between nymphs feeding on P. viburni adults and those given Galleria mellonella (L.) (Lepidoptera: Pyralidae) larvae as prey. In field trials, inundative releases of 30 P. maculiventris nymphs on naturally infested V. trilobum shrubs significantly reduced pest defoliation on shrubs infested with <3,000 larvae but had no effect on shrubs with heavier infestations. On caged branches, individual nymphs successfully developed when feeding only on P. viburni larvae. These results show that P. viburni larvae and adults are suitable prey for P. maculiventris and this predator could potentially be developed as a biological control agent against P. viburni.

An examination of saltatory predation strategies employed by fish larvae foraging in a variety of different turbulent regimes

Saltatory or pause-travel predation strategies are exhibited by a wide variety of different species of fish larvae (e.g. Atlantic cod Gadus morhua and herring Clupea harengus, white crappie Pomoxis annularis and red drum Sciaenops ocellatus), usually classified as visual predators. Given the frequency that saltatory predation behaviour is observed, one would expect that this type of foraging provides an optimal balance between the energy expended whilst swimming, as against the potential energy to be gained upon successfully capturing some suitable prey. However, visual predators must live and forage in the upper 10s of metres of the ocean mixed layer, where light levels are relatively high, which means that their ability to find and capture prey is strongly influenced by small-scale turbulence. The strength of the turbulence regime characterising the water motion of the mixed layer is subject to considerable variation, but given the commonalty of saltatory predation, one would suspect that it remains a robust strategy under a variety of different conditions. This paper seeks to address this issue by studying the impact of saltatory predation over a wide cross section of turbulent environments. By means of a combination of kinematic simulations and theoretical predictions, the paper demonstrates that saltatory predation is indeed a robust and optimal strategy in the sense described, provided the larva’s travel speed is not too high. However, when subject to very high levels of turbulence a larva’s net energy gain peaks and then falls, leading to a prediction that it would either cease foraging altogether, or seek an escape from such an environment.

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

AbstractLarvae 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.

ヒメジンガサハナカメムシの発育と繁殖におけるミナミキイロアザミウマとカンザワハダニの餌としての適合性

Effects of the prey species Thrips palmi and Tetranychus kanzawai and their stages on the development and reproduction of the anthocorid predator, Wollastoniella rotunda, were investigated under laboratory conditions. When offered first or second instar larvae of T. palmi, first instar nymphs of W. rotunda developed into second instars; however, when offered adult T. palmi females, most predator instars failed to develop into second instars. Conversely, when offered adult females and protonymphs of T. kanzawai, first instars of the predator were capable of developing into second instars. Similar findings were observed in third and fifth instars of the predator when offered either of the two prey species. No difference in predator survival and fecundity was observed when either of the two prey species was offered to females of W. rotunda. These findings indicated that T. kanzawai and T. palmi are both suitable prey species for W. rotunda, and suggest the potential for application of the predator as a biological control agent against both of these pest species.

Prey suitability of western flower thrips, Frankliniella occidentalis, and onion thrips, Thrips tabaci, for the predatory mite Amblyseius swirskii

Western flower thrips, Frankliniella occidentalis, and onion thrips, Thrips tabaci, are both important polyphagous pests of vegetables and ornamentals in greenhouses. Difficulties in biological control of these pests have prompted a search for new natural enemies. Most recently, the predatory mite Amblyseius swirskii has been commercialised as biological control agent of whiteflies and thrips. However, little is known about the suitability of thrips as prey for A. swirskii. We therefore assessed prey acceptance and life history of A. swirskii when feeding on F. occidentalis and T. tabaci at 25±1°C. Amblyseius swirskii juveniles preyed upon first larval instars of both F. occidentalis and T. tabaci but suffered from high mortality (67 and 78%). Developmental time (egg to adult) of A. swirskii was 7.8 days with either prey species. Adult A. swirskii females readily accepted first larval instars of both thrips species, which were attacked in <20 min on a leaf and <10 min in an artificial cage. Oviposition rates (0.92 and 0.99 eggs/female/day) and offspring sex ratios (63 and 70% females) were similar with F. occidentalis and T. tabaci as prey. Less than one-third of juveniles reaching adulthood and oviposition rates below one egg/female per day resulted in relatively low intrinsic rates of increase (r m) (0.056 and 0.024 per day with F. occidentalis and T. tabaci, respectively). Altogether, our study suggests that the recently reported superiority of A. swirskii to the widely used Neoseiulus cucumeris in suppression of thrips is due to other traits than its population growth capacity with thrips as prey.

Direct and indirect adverse effects of tomato on the predatory mite Neoseiulus californicus feeding on the spider mite Tetranychus evansi

AbstractPlants may defend themselves against herbivores via morphological traits, chemical traits, or a combination of both. Herbivores that overcome the defensive mechanisms of a plant tend to specialize on this plant due to enhanced protection from natural enemies. Well‐known examples of plants possessing a suite of defensive mechanisms are found in nightshades (Solanaceae), especially in the tomato genus Lycopersicon. The spider mite Tetranychus evansi Baker and Pritchard (Acari: Tetranychidae) is specialized on solanaceous plants and is an invasive pest of tomato in Europe and Africa. Biological control of T. evansi with currently available natural enemies, such as the predatory mites Phytoseiulus persimilis Athias‐Henriot and Neoseiulus californicus McGregor (both Acari: Phytoseiidae), is unsuccessful, with the underlying mechanisms only vaguely known. We hypothesized that T. evansi is a key pest of tomato because this host plant provides a two‐pronged protection from natural enemies. Direct adverse effects of tomato on predators may arise from morphological traits and/or trichome exudates, whereas indirect effects are prey‐mediated through the accumulation of toxic plant compounds. Using a 2 × 3 factorial design, we assessed and separated direct and indirect effects of tomato on the life history of N. californicus feeding on two strains of T. evansi (reared on bean or tomato) on three substrates (tomato leaf, bean leaf, and an artificial cage). Developmental time and oviposition rate of N. californicus were both directly and indirectly negatively affected by tomato whereas offspring sex ratio and survival of juveniles and adult females were unaffected. The direct and indirect, prey‐mediated adverse effects of tomato on N. californicus with T. evansi prey had similar magnitudes and were additive. We conclude that T. evansi per se is a suitable prey species for N. californicus and discuss the results with respect to the potential use of N. californicus as biological control agent of T. evansi on tomato and other host plants.

Multicellular Development in Myxococcus xanthus Is Stimulated by Predator-Prey Interactions

Myxococcus xanthus is a predatory bacterium that exhibits complex social behavior. The most pronounced behavior is the aggregation of cells into raised fruiting body structures in which cells differentiate into stress-resistant spores. In the laboratory, monocultures of M. xanthus at a very high density will reproducibly induce hundreds of randomly localized fruiting bodies when exposed to low nutrient availability and a solid surface. In this report, we analyze how M. xanthus fruiting body development proceeds in a coculture with suitable prey. Our analysis indicates that when prey bacteria are provided as a nutrient source, fruiting body aggregation is more organized, such that fruiting bodies form specifically after a step-down or loss of prey availability, whereas a step-up in prey availability inhibits fruiting body formation. This localization of aggregates occurs independently of the basal nutrient levels tested, indicating that starvation is not required for this process. Analysis of early developmental signaling relA and asgD mutants indicates that they are capable of forming fruiting body aggregates in the presence of prey, demonstrating that the stringent response and A-signal production are surprisingly not required for the initiation of fruiting behavior. However, these strains are still defective in differentiating to spores. We conclude that fruiting body formation does not occur exclusively in response to starvation and propose an alternative model in which multicellular development is driven by the interactions between M. xanthus cells and their cognate prey.

Experimental studies on the feeding ecology of &lt;i&gt;Munida subrugosa&lt;/i&gt; (White, 1847) (Decapoda: Anomura: Galatheidae) from the Magellan region, southern Chile

SUMMARY: Feeding behaviour and food uptake rates of the anomuran crab Munida subrugosa from the southern Magellan region (Chile) were studied under laboratory conditions. Crabs exhibited a marked preference for meat versus macroalgae, with uptake rates being 14 times higher. Different algal species were ranked according to structure and detrital cover. Observations suggest that scavenging and cannibalism, restricted to injured or moulting individuals, are regularly applied in the natural habitat, whereas active hunting is only performed on suitable prey. The main food resource is suggested to be of microscopic origin, given the time spent on typical food uptake movements for detritus and suspended food. The findings of this study, backed up by results of simultaneously carried out stomach analysis, proved M. subrugosa to be an opportunistic feeder that can make use of different forms of food uptake.

A spatially explicit optimal foraging model of Black-legged Kittiwake behavior based on prey density, travel distances, and colony size

We developed a spatially explicit population model (FORAGER) that simulates the foraging movements of Black-legged Kittiwakes ( Rissa tridactyla) in Prince William Sound (PWS), Alaska, an oceanographically, spatially, and temporally complex marine environment where the foraging behavior of this species has been extensively studied. Kittiwake foraging behavior had been previously modeled in the North Sea, an area spatially less complex than PWS, and we make comparisons to those studies. We calibrated and evaluated FORAGER by comparing predicted with observed bird movements, as well as with the predictions of a multiple regression model. Empirical data were derived from radio-telemetered kittiwakes tracked in an area where aerial surveys were determining the distribution and abundance of suitable prey schools over two years. The model simulated a predator searching for a school in a grid-based (2.78 km × 2.78 km) environment. The simulated predator is aware of fish-school density within a specified neighborhood around its current grid cell, and moves to an adjacent cell in order to maximize its prey encounter rate while avoiding cells that are primarily land. When a school is successfully found and exploited, the kittiwake returns to its colony by direct flight. Colony foraging grounds are created by simulating multiple foraging trips, each based on a different distribution of fish schools created by randomly perturbing the observed distributions. The four-parameter FORAGER model outperformed comparable multiple regression models, explaining on average 68% of the variation in observed kittiwake foraging behavior using a polar grid, and 44% using a rectangular grid. A four-parameter multiple regression model based on the same data set accounted for only 35 and 28% of the variation, respectively, depending on grid structure. Comparison of simulated and observed behavior suggests that kittiwakes in PWS plan their movements only within a neighborhood of about four grid cells, rely heavily on information gathered while foraging (including both negative and positive indications from conspecifics), and rely only somewhat on memory of prey distribution, as has been hypothesized to be effective in less complex regions (North Sea). FORAGER predicts that kittiwake movements should differ from the Ideal Free Distribution because of the predators’ uncertainty as to the actual prey distribution. Model results also indicate little relationship between the actual location of breeding colonies and local areas of high prey availability. Comparison of actual colony locations with randomly sited colony locations, however, showed that the former minimize the interaction among foraging kittiwakes from different colonies.

The food and feeding relationships of larval and 0+ year juvenile fishes in lowland rivers and connected waterbodies. I. Ontogenetic shifts and interspecific diet similarity

Many fish species are zooplanktivorous at the onset of exogenous feeding, but distinct shifts in their foraging biology may occur with development. This study investigated the food and feeding relationships of the larvae and 0+ year juveniles of 13 fish species in ‘main river’, ‘marina’ and ‘pond’ macrohabitats in the lower River Trent, England. Young larvae had narrow diet spectra, with feeding diversity and the importance of species‐specific traits increasing with development. Two main ontogenetic shifts in diet were differentiated, corresponding with the transition from finfold to finformed larvae, and from the larval to the juvenile period. Dietary overlap was generally greatest among ecologically similar species, with competition and resource partitioning most likely where prey availability was lowest. The greater availability of zooplankton in connected waterbodies compared with main river channels provides suitable prey for a wide range of fish species, and may enhance recruitment success.

The food and feeding relationships of larval and 0+ year juvenile fishes in lowland rivers and connected waterbodies. II. Prey selection and the influence of gape

The relative importance of taxa‐ and size‐specific prey selection, and the influence of gape on the prey consumed by the larvae and 0+ year juveniles of four fish species were investigated in ‘main river’, ‘marina’ and ‘pond’ macrohabitats in the lower River Trent, England. A general sequence of ontogenetic shifts in food consumption was reflected in the electivity indices of particular prey taxa, partly due to the restrictions imposed by the gape of 0+ year fishes. Certain taxa, however, were consistently selected over others, irrespective of size, suggesting that taxa‐specific, as well as size‐specific, prey characteristics may be important in the selection process. There were significant, positive relationships between maximum prey (zooplankton) length and maximum gape height for larvae, but not for 0+ year juveniles. The majority of fishes, however, consumed prey substantially smaller than the maximum theoretically possible inferred from their gape. The greater size ranges of zooplankton in connected waterbodies compared with main river channels provide suitable prey for a range of developmental steps and fish species, and may, thus, enhance recruitment success.

Aspects of prey relations in the coccidophagous ladybird Chilocorus nigritus relevant to its use as a biological control agent of scale insects in temperate glasshouses

The armoured scale insects Acutaspis umbonifera (Newstead), Pinnaspis buxi (Bouche) (Homoptera: Diaspididae) and the soft scale insects Saissetia coffeae (Walker) and Coccus hesperidum L. (Homoptera: Coccidae) were tested as suitable prey for the ladybird Chilocorus nigritus (F.) (Coleoptera: Coccinellidae), with a view to using the beetle as a biological control agent in UK glasshouses. C. nigritus larvae were able to complete development on all prey species tested and adults were also able to mature eggs on P. buxi, S. coffeae and C. hesperidum (A. umbonifera was not tested in this respect). Prey in ornamental glasshouses and interior landscapes are often diverse and patchily distributed. Thus the effect on the beetle larvae of switching between diaspidid and coccid prey was also examined. Larvae were able to switch from feeding on C. hesperidum to Abgrallaspis cyanophylli (Signoret) (Homoptera: Diaspididae) and vice versa with only minor detrimental effects when compared to those beetles reared throughout on one prey species. Introductions of C. nigritus as eggs, rather than adults are indicated for the control of soft scale species.

Bdellovibrio Predation in the Presence of Decoys: Three-Way Bacterial Interactions Revealed by Mathematical and Experimental Analyses

Bdellovibrio bacteriovorus is a small, gram-negative, motile bacterium that preys upon other gram-negative bacteria, including several known human pathogens. Its predation efficiency is usually studied in pure cultures containing solely B. bacteriovorus and a suitable prey. However, in natural environments, as well as in any possible biomedical uses as an antimicrobial, Bdellovibrio is predatory in the presence of diverse decoys, including live nonsusceptible bacteria, eukaryotic cells, and cell debris. Here we gathered and mathematically modeled data from three-member cultures containing predator, prey, and nonsusceptible bacterial decoys. Specifically, we studied the rate of predation of planktonic late-log-phase Escherichia coli S17-1 prey by B. bacteriovorus HD100, both in the presence and in the absence of Bacillus subtilis nonsporulating strain 671, which acted as a live bacterial decoy. Interestingly, we found that although addition of the live Bacillus decoy did decrease the rate of Bdellovibrio predation in liquid cultures, this addition also resulted in a partially compensatory enhancement of the availability of prey for predation. This effect resulted in a higher final yield of Bdellovibrio than would be predicted for a simple inert decoy. Our mathematical model accounts for both negative and positive effects of predator-prey-decoy interactions in the closed batch environment. In addition, it informs considerations for predator dosing in any future therapeutic applications and sheds some light on considerations for modeling the massively complex interactions of real mixed bacterial populations in nature.