New primary resource increases predation on a pest in a banana agroecosystem

• 1 Primary resources may affect the structure of species assemblages in upper trophic levels of food webs. These bottom‐up effects may involve important ecological processes that affect pest control. For example, population densities of natural enemies may increase when alternative preys are favoured by a new resource.
• 2 Ants, particularly Solenopsis geminata Forel (Myrmicinae), are recognized as effective predators of herbivores eggs. In the present study, we tested the hypothesis that the addition of a primary resource in a banana agroecosystem will increase pest control of the banana weevil Cosmopolites sordidus Germar (Coleoptera, Curculionidae) by ants.
• 3 Using stable isotope analyses, we showed that S. geminata used the new resource pathway provided by the addition of a cover crop. This change was revealed by increased δ¹³C values (¹³C/¹²C) in a cover crop treatment (C4 plant) compared with a banana (C3 plant) in bare soil treatment.
• 4 We also showed that the abundance of S. geminata, as measured with pitfall traps, was 4.8–5.4‐fold higher in the cover crop treatment than in the bare soil treatment. Estimation of egg predation rates was in the range 7.8–70.3%, which occurred in plots with the lowest and highest S. geminata numbers, respectively.
• 5 The addition of a new primary resource in this system changed the origin of the carbon consumed by predators and increased their densities. The increased ant abundance resulted in increased predation of weevil eggs, which was consistent with our hypothesis. These results will be useful for the design of cropping systems that enhance the biological regulation of pests.

     

Weeds mediate the level of intraguild predation in arthropod food webs

Intraguild predation, which is common for generalist predators, is a specific form of omnivory that may suppress the biological control of a pest. The dietary flexibility of a given organism depends on the choice of the C3 (banana crop) and the C4 (weeds) pathways they use and on the trophic level on which they feed. Understanding the conditions in which intraguild predation decreases biological control is a major issue in agroecosystems. We tested whether the contribution of different primary producer pathways in diets of generalist predators mediates the level of intraguild predation. We studied 10 agroecosystems in which banana plants (C3 metabolism) were diversely associated with weeds (C4 metabolism). Diversity in litter macrofauna was relatively low, with a mean between three and eight species per trap. Measurement of stable isotopes showed a significant decrease in the δ¹⁵N values of generalist predators when the C4 pathway contributed more than the C3 pathway to their diet. We rejected hypotheses that an increase in the abundance of prey and that a decrease in prey's δ¹⁵N values occur when the C4 pathway contributes more than the C3 pathway to their diet. The results are consistent with the diet modification hypothesis, that is, intraguild predation is lower when the C4 (weeds) pathway is preferred to the C3 pathway. Our results suggest that when the C4 pathway of weeds is more exploited by herbivores (or detritivores), generalist predators tend to consume these herbivores and thus neglect the intraguild prey. The diverse C4 plant community probably supports a diverse herbivore community that provides alternative prey. Our results provide evidence that increasing plant diversity in agroecosystems should decrease intraguild predation of generalist predators and should therefore improve pest regulation. In an applied perspective, plant diversity could be increased by establishing a more diverse cover‐crop community.     

Molecular gut-content analysis of a predator assemblage reveals the effect of habitat manipulation on biological control in the field

Habitat manipulation in agroecosystems can influence predator–prey interactions. In this study, we collected foliar predators from field potato plots with different mulch treatments and assayed them for DNA of the target prey, Leptinotarsa decemlineata (Say), using species-specific primers. Concurrently, L. decemlineata larval abundance and plant damage were recorded from the same plots. Predator species abundance and diversity were not influenced by habitat manipulation, while prey density was highest in plots without mulch. Gut-content analysis revealed that the highest incidence of predators positive for L. decemlineata DNA was in plots without mulch, where target prey abundance was highest. Therefore, the lower prey abundance in mulched plots was not due to predation. The most abundant species in the predator assemblage was Coleomegilla maculata, which had the lowest proportion of L. decemlineata DNA in the gut. Podisus maculiventris, Perillus bioculatus, and Lebia grandis were less abundant but had a higher incidence of target prey DNA in the gut. DNA detectability half-lives were used to adjust for inter-specific variation in DNA digestive rates of the four predator species. Using this information to adjust actual number of positives for prey DNA, we compared proportions positive for L. decemlineata and found that P. maculiventris is the most effective predator species in the complex.     

Linking habitat complexity with predation of pests through molecular gut-content analyses

Improving the diversity of farm systems or landscapes can lead to more effective biological control by providing refuge and alternative resources for colonising natural enemies. Within an experimental cabbage agroecosystem, we examined the effects of habitat management (i.e. herbicide use and cover crops) on pest populations and predator community structure, and report one of the first studies on the trophic links in this system using molecular gut-content analysis. In response to herbicide and cover crop management treatments designed to create different levels of habitat diversity, we quantified the abundance of two pests, Plutella xylostella Linnaeus (Lepidoptera: Plutellidae) and Pieris rapae Linnaeus (Lepidoptera: Pieridae), and predators. We designed species-specific primers to detect prey DNA in predators' guts. Pieris rapae were significantly more abundant in plots where cover crops were killed early in the season, and habitat management generated unique predator communities in response to weed management treatments. Thirty-five per cent of predators tested positive for prey DNA, and habitat management had interactive effects on predation of P. xylostella. Combined we found that habitat management has variable effects on natural enemy–pest interactions.     

The challenge of biological control of Cosmopolites sordidus Germar (Col. Curculionidae): A review

The banana weevil (also known as banana root borer) Cosmopolites sordidus Germar (Coleoptera Curculionidae) is the major pest of banana and plantain. Because banana ranks 2nd in fruit production worldwide, this pest has substantial social and economic importance. The biological control of the C. sordidus remains challenging because of its behaviour and resistance to parasitism and predation. The last review concerning the biological control of C. sordidus was published two decades ago, and relevant knowledge and methods have developed in the interim. The present paper provides an update of that knowledge and summarizes past and current challenges as well as providing perspectives on achieving sustainable control of C. sordidus. We first discuss studies on the classical biological control of C. sordidus, underlining the limits of classical biological control methods such as the importation of predators, parasitoids or pathogens. Next, we consider conservation biological control of C. sordidus, with a focus on ants. We also highlight an ‘arthropod bias’ that has led to a lack of information on the role of vertebrates in the regulation of C. sordidus.     

Parasitism-mediated prey selectivity in laboratory conditions and implications for biological control

In agroecosystems, parasitoids and predators may exert top-down regulation and predators for different reasons may avoid or give preference to parasitised prey, i.e., become an intraguild predator. The success of pest suppression with multiple natural enemies depends essentially on predator–prey dynamics and how this is affected by the interplay between predation and parasitism. We conducted a simple laboratory experiment to test whether predators distinguished parasitised prey from non-parasitised prey and to study how parasitism influenced predation. We used a host-parasitoid system, Spodoptera frugiperda and one of its generalist parasitoids, Campoletis flavicincta, and included two predators, the stinkbug Podisus nigrispinus and the earwig Euborellia annulipes. In the experiment, predators were offered a choice between non-parasitised and parasitised larvae. We observed how long it took for the predator to attack a larva, which prey was attacked first, and whether predators opted to consume the other prey after their initial attack. Our results suggest that, in general, female predators are less selective than males and predators are more likely to consume non-parasitised prey with this likelihood being directly proportional to the time taken until the first prey attack. We used statistical models to show that males opted to consume the other prey with a significantly higher probability if they attacked a parasitised larva first, while females did so with the same probability irrespective of which one they attacked first. These results highlight the importance of studies on predator–parasitoid interactions, as well as on coexistence mechanisms in agroecosystems. When parasitism mediates predator choice so that intraguild predation is avoided, natural enemy populations may be larger, thus increasing the probability of more successful biological control.     

Interaction between the predator Xylocoris sordidus and Bacillus thuringiensis bioinsecticides

Xylocoris species (Hemiptera: Anthocoridae) are known to occur in various habitats and attack a diversity of agriculturally important prey. Other groups of organisms, such as strains of Bacillus thuringiensis Berliner (Bt) bacteria, also have been extensively studied and applied as biological control agents. The use of these Bt-bioinsecticides in association with predators may be a good strategy in integrated pest management. This work had the objective to study predator behaviour, predatory capacity, and functional response of fifth-instar nymphs of Xylocoris sordidus (Reuter) to eggs of Plutella xylostella (L.) (Lepidoptera: Plutellidae) and Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) treated with one of three commercial Bt-bioinsecticides. The predator presented a type II functional response to untreated P. xylostella eggs (control) and to eggs treated with Agree, whereas the response was type III to P. xylostella eggs treated with Xentari and Dipel. However, on a diet of C. cephalonica eggs the predator displayed a type II response curve on eggs treated with each of the three bioinsecticides, and a type III response on untreated eggs. Bioinsecticides based on B. thuringiensis may be used in association with X. sordidus predators to control lepidopterous pest species.     

Diversity of protists and bacteria determines predation performance and stability

Predation influences prey diversity and productivity while it effectuates the flux and reallocation of organic nutrients into biomass at higher trophic levels. However, it is unknown how bacterivorous protists are influenced by the diversity of their bacterial prey. Using 456 microcosms, in which different bacterial mixtures with equal initial cell numbers were exposed to single or multiple predators (Tetrahymena sp., Poterioochromonas sp. and Acanthamoeba sp.), we showed that increasing prey richness enhanced production of single predators. The extent of the response depended, however, on predator identity. Bacterial prey richness had a stabilizing effect on predator performance in that it reduced variability in predator production. Further, prey richness tended to enhance predator evenness in the predation experiment including all three protists predators (multiple predation experiment). However, we also observed a negative relationship between prey richness and predator production in multiple predation experiments. Mathematical analysis of potential ecological mechanisms of positive predator diversity—functioning relationships revealed predator complementarity as a factor responsible for both enhanced predator production and prey reduction. We suggest that the diversity at both trophic levels interactively determines protistan performance and might have implications in microbial ecosystem processes and services.     

Habitat effects on second-order predation of the seed predator Harpalus rufipes and implications for weed seedbank management

Seed predators provide a valuable ecosystem service to farmers by reducing densities of weed seeds, and, in turn, densities of weed seedlings they must manage. The predominant invertebrate weed seed predator in Maine, USA, agroecosystems is the carabid beetle Harpalus rufipes DeGeer. Pitfall trapping has shown that H. rufipes prefers sites with vegetative cover to fallow sites, preference speculated to be driven by predator avoidance behavior. To test this hypothesis, ‘second-order predation assays’ were developed, in which live H. rufipes prey were presented to second-order predators. Field experiments were conducted to determine foremost if H. rufipes was subject to second-order predation, and secondly, whether (a) vegetative cover affords H. rufipes protection from second-order predators, and (b) high rates of second-order predation correspond with decreased invertebrate seed predation rates. Two 72-h experiments were conducted (mid August and September 2012) at crop and non-crop sites across a 28 ha diversified farm in Stillwater, ME, USA.Second-order predation was 2.8% per day. Based on images from motion-sensing cameras, H. rufipes’ predators included birds and small mammals. Neither a relationship between second-order predation and vegetative treatment, nor an empirical relationship between second-order predation and invertebrate seed predation were detected. However, a simulation model predicted that 2.8% per day second-order predation could increase the number of seeds entering the seedbank by more than 17% annually. Additionally, complex habitats supported higher rates of second-order predation than did simple habitats.     

18S rRNA metabarcoding diet analysis of a predatory fish community across seasonal changes in prey availability

Predator–prey relationships are important ecological interactions, affecting biotic community composition and energy flow through a system, and are of interest to ecologists and managers. Morphological diet analysis has been the primary method used to quantify the diets of predators, but emerging molecular techniques using genetic data can provide more accurate estimates of relative diet composition. This study used sequences from the 18S V9 rRNA barcoding region to identify prey items in the gastrointestinal (GI) tracts of predatory fishes. Predator GI samples were taken from the Black River, Cheboygan Co., MI, USA (n = 367 samples, 12 predator species) during periods of high prey availability, including the larval stage of regionally threatened lake sturgeon (Acipenser fulvescens Rafinesque 1817) in late May/early June of 2015 and of relatively lower prey availability in early July of 2015. DNA was extracted and sequenced from 355 samples (96.7%), and prey DNA was identified in 286 of the 355 samples (80.6%). Prey were grouped into 33 ecologically significant taxonomic groups based on the lowest taxonomic level sequences that could be identified using sequences available on GenBank. Changes in the makeup of diet composition, dietary overlap, and predator preference were analyzed comparing the periods of high and low prey abundance. Some predator species exhibited significant seasonal changes in diet composition. Dietary overlap was slightly but significantly higher during the period of high prey abundance; however, there was little change in predator preference. This suggests that change in prey availability was the driving factor in changing predator diet composition and dietary overlap. This study demonstrates the utility of molecular diet analysis and how temporal variability in community composition adds complexity to predator–prey interactions.     

Reciprocity in predator–prey interactions: exposure to defended prey and predation risk affects intermediate predator life history and morphology

A vast body of literature exists documenting the morphological, behavioural and life history changes that predators induce in prey. However, little attention has been paid to how these induced changes feed back and affect the predators’ life history and morphology. Larvae of the phantom midge Chaoborus flavicans are intermediate predators in a food web with Daphnia pulex as the basal resource and planktivorous fish as the top predator. C. flavicans prey on D. pulex and are themselves prey for fish; as D. pulex induce morphological defences in the presence of C. flavicans this is an ideal system in which to evaluate the effects of defended prey and top predators on an intermediate consumer. We assessed the impact on C. flavicans life history and morphology of foraging on defended prey while also being exposed to the non-lethal presence of a top fish predator. We tested the basic hypothesis that the effects of defended prey will depend on the presence or absence of top predator predation risk. Feeding rate was significantly reduced and time to pupation was significantly increased by defended morph prey. Gut size, development time, fecundity, egg size and reproductive effort respond to fish chemical cues directly or significantly alter the relationship between a trait and body size. We found no significant interactions between prey morph and the non-lethal presence of a top predator, suggesting that the effects of these two biological factors were additive or singularly independent. Overall it appears that C. flavicans is able to substantially modify several aspects of its biology, and while some changes appear mere consequences of resource limitation others appear facultative in nature.     

Gut content examination of the citrus predator assemblage for the presence of Homalodisca vitripennis remains

A two-year study was conducted in a citrus orchard, Citrus sinensis L., to determine frequency of predation on glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar). A total of 1,578 arthropod predators, representing 18 taxa, were collected and assayed for the presence of GWSS egg protein by an enzyme-linked immunosorbent assay using a Homalodisca-species and egg-specific monoclonal antibody and then by polymerase chain reaction using a H. vitripennis-specific DNA marker. The gut content analyses revealed the presence of GWSS remains in the gut of 2.28 % of the total arthropod predator population, with 3.09 % of the spiders and 0.59 % of the insect predators testing positive. Moreover, a comparison of the two assays indicated that they were not equally effective at detecting GWSS remains in predator guts. Low frequencies of GWSS detection in the gut of predators indicated that GWSS are not a primary prey and that predators may contribute little to suppression of this pest in citrus.     

Invertebrate biodiversity affects predator fitness and hence potential to control pests in crops

Natural enemies that control pests usually allow farmers to avoid, or reduce, the use of pesticides. However, modern farming practices, that maximize yields, are resulting in loss of biodiversity, particularly prey diversity. Does this matter? Pests continue to thrive, and without alternative prey the predators should, perforce, concentrate their attentions upon the pests.We showed that a diverse diet significantly enhances predator fecundity and survival. Experiments were conducted using common generalist predators found in arable fields in Europe, the carabid beetle Pterostichus melanarius (Coleoptera: Carabidae) and the linyphiid spider Erigone atra (Araneae: Linyphiidae). We tested the hypothesis that mixed species diets were optimal, compared with restricted diets, with respect to parameters such as predator weights, egg weights, numbers of eggs laid, egg development times, egg hatching rates and predator survival. In carabids, an exclusive earthworm diet was as good as mixed diets containing earthworms for egg production and hatching, but less good than such mixed diets for increase in beetle mass and sustained egg laying. For spiders, aphids alone (Sitobion avenae) or with the Collembola Folsomia candida, drastically reduced survival. Aphids plus the Collembola Isotoma anglicana improved survival but only aphids with a mixed Collembola diet maximized numbers of hatching eggs.Predators offered only pests (slugs or aphids) had lowest growth rates and fecundity. We therefore demonstrated that conservation of a diversity of prey species within farmland, allowing predators to exploit a diverse diet, is essential if predators are to continue to thrive in crops and regulate agricultural pests.     

Increased control of thrips and aphids in greenhouses with two species of generalist predatory bugs involved in intraguild predation

The combined release of species of generalist predators can enhance multiple pest control when the predators feed on different prey, but, in theory, predators may be excluded through predation on each other. This study evaluated the co-occurrence of the generalist predators Macrolophus pygmaeus Rambur and Orius laevigatus (Fieber) and their control of two pests in a sweet pepper crop. Both predators consume pollen and nectar in sweet pepper flowers, prey on thrips and aphids, and O. laevigatus is an intraguild predator of M. pygmaeus. Observations in a commercial sweet pepper crop in a greenhouse with low densities of pests showed that the two predator species coexisted for 8 months. Moreover, their distributions in flowers suggested that they were neither attracted to each other, nor avoided or excluded each other. A greenhouse experiment showed that the predators together clearly controlled thrips and aphids better than each of them separately. Thrips control was significantly better in the presence of O. laevigatus and aphid control was significantly better in the presence of M. pygmaeus. Hence, combined inoculative releases of M. pygmaeus and O. laevigatus seem to be a good solution for controlling both thrips and aphids in greenhouse-grown sweet pepper. The predators are able to persist in one crop for a sufficiently long period and they complement each other in the control of both pests. This study also provides further evidence that intraguild predation does not necessarily have negative effects on biological control.     

Prey selection and the impact of the starfish Marthasterias glacialis (L.) and other predators on the mussel Choromytilus Meridionalis (Krauss)

The diet of the starfish, Marthasterias glacialis (L.), consists of a variety of mollusc species, as well as ascidians and barnacles. Starfish densities are maximal where mussels, Choromytilus meridionalis (Krauss), are abundant and in such areas mussels form the bulk of the diet. Laboratory feeding experiments indicate that Marthasterias glacialis select mussels of particular sizes and that the length of prey taken is an increasing function of predator arm length. The time taken to consume each mussel is determined by the ratio of shell length to starfish size. The number of mussels consumed per day increases only slightly with starfish size, but because the prey taken increase in size, energy consumption is maintained at a relatively consistent 1% of predator body energy per day. Using prey selection and feeding rate data for different sized starfish, predictive three dimensional predation surfaces are developed for a natural starfish population feeding on either one or two cohort Choromytilus meridionalis populations. The models indicate that predatory effort should be concentrated on the smallest mussels when a single adult cohort is present, but on recruiting mussels just above the minimum prey size limit where two cohorts are present. Other major predators of mussels, the rock lobster, Jasus lalandii (Milne Edwards), and the whelk, Natica tecta Anton, appear to select similar size-ranges of prey to starfish, despite their differing body forms and feeding methods. Since the juveniles of all three predators can only take small mussels, predator recruitment may well depend upon the successful settlement of strong mussel cohorts. Evidence for such entrainment of predator cohorts to settlements of mussels is presented.     

Natural born killers: an invasive amphipod is predatory throughout its life-history

Introduced predators can have profound impacts on prey populations, with subsequent ramifications throughout entire ecosystems. However, studies of predator–prey interaction strengths in community and food-web analyses focus on adults or use average body sizes. This ignores ontogenetic changes, or lack thereof, in predatory capabilities over the life-histories of predators. Additionally, large individual predators might not be physically capable of consuming very small prey individuals. Both situations are important to resolve, as native prey may or may not therefore experience ontogenetic or size refuges from invasive predators. Here, we find that the freshwater amphipod invader, Gammarus pulex, is predatory throughout its development from juvenile through to adult. All size classes collected in the field had a common prey, nymphs of the mayfly Baetis rhodani, in their guts. In an experiment with predator, prey and experimental arenas scaled for body size, G. pulex juveniles and adults consumed B. rhodani in all size-matched categories. In a second experiment, the largest G. pulex individuals were able to prey on the smallest B. rhodani. Thus, the prey do not benefit from any ontogenetic or size refuge from the predator. This corroborates with the known negative population abundance relationships between this invasive predator and its native prey species. Understanding and predicting invasive predator impacts will be best served when interactions among all life-history stages of predator and prey are considered.     

Behavioural and life history effects of predator diet cues during ontogeny in damselfly larvae

A central issue in predator–prey interactions is how predator associated chemical cues affect the behaviour and life history of prey. In this study, we investigated how growth and behaviour during ontogeny of a damselfly larva (Coenagrion hastulatum) in high and low food environments was affected by the diet of a predator (Aeshna juncea). We reared larvae in three different predator treatments; no predator, predator feeding on conspecifics and predator feeding on heterospecifics. We found that, independent of food availability, larvae displayed the strongest anti-predator behaviours where predators consumed prey conspecifics. Interestingly, the effect of predator diet on prey activity was only present early in ontogeny, whereas late in ontogeny no difference in prey activity between treatments could be found. In contrast, the significant effect of predator diet on prey spatial distribution was unaffected by time. Larval size was affected by both food availability and predator diet. Larvae reared in the high food treatment grew larger than larvae in the low food treatment. Mean larval size was smallest in the treatment where predators consumed prey conspecifics, intermediate where predators consumed heterospecifics and largest in the treatment without predators. The difference in mean larval size between treatments is probably an effect of reduced larval feeding, due to behavioural responses to chemical cues associated with predator diet. Our study suggests that anti-predator responses can be specific for certain stages in ontogeny. This finding shows the importance of considering where in its ontogeny a study organism is before results are interpreted and generalisations are made. Furthermore, this finding accentuates the importance of long-term studies and may have implications for how results generated by short-term studies can be used.     

Mammalian predator–prey interaction in a fragmented landscape: weasels and voles

The relationship between predators and prey is thought to change due to habitat loss and fragmentation, but patterns regarding the direction of the effect are lacking. The common prediction is that specialized predators, often more dependent on a certain habitat type, should be more vulnerable to habitat loss compared to generalist predators, but actual fragmentation effects are unknown. If a predator is small and vulnerable to predation by other larger predators through intra-guild predation, habitat fragmentation will similarly affect both the prey and the small predator. In this case, the predator is predicted to behave similarly to the prey and avoid open and risky areas. We studied a specialist predator’s, the least weasel, Mustela nivalis nivalis, spacing behavior and hunting efficiency on bank voles, Myodes glareolus, in an experimentally fragmented habitat. The habitat consisted of either one large habitat patch (non-fragmented) or four small habitat patches (fragmented) with the same total area. The study was replicated in summer and autumn during a year with high avian predation risk for both voles and weasels. As predicted, weasels under radio-surveillance killed more voles in the non-fragmented habitat which also provided cover from avian predators during their prey search. However, this was only during autumn, when the killing rate was also generally high due to cold weather. The movement areas were the same for both sexes and both fragmentation treatments, but weasels of both sexes were more prone to take risks in crossing the open matrix in the fragmented treatment. Our results support the hypothesis that habitat fragmentation may increase the persistence of specialist predator and prey populations if predators are limited in the same habitat as their prey and they share the same risk from avian predation.     

Effects of the probability of a predator catching prey on predator–prey system stability

To understand the effect of the probability of a predator catching prey, P_catch, on the stability of the predator–prey system, a spatially explicit lattice model consisting of predators, prey, and grass was constructed. The predators and prey randomly move on the lattice space, and the grass grows according to its growth probability. When a predator encounters prey, the predator eats the prey in accordance with the probability P_catch. When a prey encounters grass, the prey eats the grass. The predator and prey give birth to offspring according to a birth probability after eating prey or grass, respectively. When a predator or prey is initially introduced or newly born, its health state is set at a high given value. This health state decreases by one with every time step. When the state of an animal decreases to less than zero, the individual dies and is removed from the system. Population densities for predator and prey fluctuated significantly according to P_catch. System stability was characterized by the standard deviation ? of the fluctuation. The simulation results showed that ? for predators increased with an increase of P_catch; ? for prey reached a maximum at P_catch = 0.4; and ? for grass fluctuated little regardless of P_catch. These results were due to the tradeoff between P_catch and the predator–prey encounter rate, which represents the degree of interaction between predator and prey and the average population density, respectively.     

The influence of time and temperature on molecular gut content analysis： Adalia bipunctata fed with Rhopalosiphum padi

Gut content analysis is a useful tool when studying arthropod predator-prey interactions. We used polymerase chain reaction （PCR） technique to examine how detection of prey DNA in the gut content of predators was influenced by digestion time and temperature. Such knowledge is critical before applying PCR-based gut content analysis to field collected predators. Larvae of the two-spotted ladybeetle （Adalia bipunctata L.） were fed with the bird cherry-oat aphid （Rhopalosiphum padi L.） at either 21℃ or 14℃. After consuming one aphid, the predators were allowed to digest the prey for a range of time periods up to 24 hours. The influence of temperature on A. bipunctata feeding behavior was also recorded. From the fed larvae, total DNA was extracted and PCR reactions with R. padi specific primers were run. The number ofA. bipunctata that tested positive for R. padi DNA was negatively related to the length of digestion time. Temperature influenced larval feeding behavior but did not have a significant effect on R. padi DNA detection. After pooling the data from both temperature treatments we estimated the time point when R. padi DNA could be amplified from 50% of the fed A. bipunctata by PCR to be 4.87 hours. With such a rapid decrease in prey DNA detection success, positive PCR reactions will most likely be the result of predation events occurring shortly before capture. If a defined digestion temperature range has proven not to influence prey detection, PCR data obtained from predators collected within that particular range can be interpreted in the same way.