Egg Predation Research Articles

Mantidfly larvae use cues on substrate to locate and distinguish different sexes and life stages of potential spider hosts

In many animals, early-life decisions influence long-term fitness. Mantidflies are spider egg predators; their tiny larvae climb aboard spiders to find eggs, but little is known about how they find spiders. We tested the hypothesis that mantidfly larvae (Dicromantispa sayi) detect and respond to substrate-borne spider cues (e.g., silk and/or excreta). We presented larvae with filter paper exposed to different types of spiders (adult female, adult male, or juvenile Habronattus trimaculatus jumping spiders) versus a no-cue control. Larvae spent more time on filter paper with spider cues. We then tested the hypothesis that mantidflies make finer distinctions between spiders when given direct choices between these cues. Larvae did not discriminate between sexes but spent more time (and exhibited more phoretic behavior) on filter paper with female or male cues compared with juvenile cues. While this suggests that mantidflies actively seek out adult spiders, we also found that adult spiders were more active than juveniles and may have simply deposited more silk and excreta, providing a stronger cue to detect. We discuss these findings in the context of the risks and benefits of different spider hosts, and how early-life spider-searching strategies may shape a mantidfly’s long-term fitness.

Predation rates on flatback turtle Natator depressus eggs and hatchlings at an island rookery

Predation can significantly threaten the vulnerable egg and hatchling stages of sea turtles, yet for most populations this remains poorly quantified for use in conservation. We provided the first quantified predation rates of flatback turtle eggs and hatchlings at Thevenard Island, a medium-sized rookery on the northwest coast of Australia, with a focus on ghost crabs as potential predators. Burrow densities were used as proxy for ghost crab densities, while start- and end-of-season nest inventories and infrared videography were used to quantify egg and hatchling predation, respectively. Inventories of 27 nests suggested a mean hatching success of 74.2 ± 4.6% with zero predation of eggs, while videography at 17 nests indicated that 30.1 ± 8.1% of emerged hatchlings were predated, mainly by ghost crabs. Females selecting nest locations not easily accessible to ghost crabs, or the composition of flatback’s eggshells may explain the lack of egg predation. A 44.0% egg-to-surf survival rate was estimated, almost double the rate estimated for C. caretta on the Ningaloo coast (24.4%) using similar techniques. Further work is needed to understand if those predation rates are sustainable for recovering threatened species and if mitigation efforts tailored to each species and each life stage are needed.

Predation of Rock Partridge Alectoris graeca saxatilis nests incubated by males and females in the French Alps

ABSTRACT Capsule The predation of incubated nests was investigated in an Alpine population of Rock Partridges, showing a double-nesting behaviour by females that can lay two clutches in succession, one incubated by the mated male and the second by the female. Aims To compare the nest predation rate and hatching success between incubating males and females in relation to the potential effects of year, nest age, and environmental characteristics (presence of nest cameras, visibility of the clutch, and vegetation cover around the nest). Methods The fate of 100 nests incubated by radio-tracked birds was monitored daily over 1738 days using cameras, and with temperature loggers placed in the nest cup. Nest predation rates and daily predation rates were calculated and modelled. Results Egg predation was the main cause of nest loss (87%) followed by predation of the incubating parent during recess periods off the nest (10%). Only mammals were identified as nest predators, and predation events were less frequent during the day than at night. We found no difference in predation rates between nests incubated by males or females. Daily and 25-day predation rates were calculated as 0.02 (95% CI: 0.01–0.03) and 0.39 (95% CI: 0.29–0.49), respectively. Median hatching success was 0.91 (n = 53 nests) and did not differ between sexes. Conclusions The similar level of nest predation between incubating males and females suggested a duplication of the reproductive output of a pair by double-nesting. Consequences of this breeding system were an increase in productivity at the population level. There was no difference in hatching success in nests incubated by either sex and there were no observations of surviving males deserting their nests, suggesting that care during incubation was similar in males and females. Variation in the rate of double-nesting may contribute more than nest predation to the annual variation in reproductive output.

Nest raiding by bonnet macaques (Macaca radiata) and the response of nest guarding birds in a suburban habitat.

In many primate species, nest raiding is a form of opportunistic foraging behavior designed to acquire protein-rich eggs and nestlings. In urban environments, this is a significant cause of nest failure in birds. Here, we describe nest raiding and egg predation in bonnet macaques (Macaca radiata) inhabiting a suburban area of Salem, Tamil Nadu, India. During nest raiding, large-billed crows (Corvus macrorhynchos) and house crows (Corvus splendens), actively defended their nest from the macaques. When several macaque foragers jointly raided the nest, they were successful in obtaining and consuming the eggs. In contrast, when a solitary macaque attempted to raid the nest, it was unsuccessful. Bird size appeared to play an important role in nest defense. Small birds, such as the scaly breasted munia (Lonchura punctulata) and the purple sunbird (Cinnyris asiaticus) were not able to protect their nests from lone bonnet macaques. These observations indicate that in urban landscapes, bonnet macaques are egg predators of many bird species. When macaques coordinate their actions and forage in small subgroups, they were more successful in preying on the eggs of larger-bodied bird species.

Predation of eggs and incubating females in willow ptarmigan Lagopus l. lagopus

Nest predation is a major cause of reproductive loss in many ground-nesting birds. During 15 consecutive years the predation of nests and females throughout the incubation season were recorded in a willow ptarmigan Lagopus l. lagopus population in central Norway. The temporal predation patterns, factors affecting the predation probability and age-specific nesting patterns in this species were studied. There was a large annual variation in predation rate of both nests (0-50%) and incubating females (0-29%) in this area during the study period. The mean annual predation rate of nests (15%) was on average three times higher than the predation of incubating willow ptarmigan females (5%). Predation rate was not constant throughout the incubation season, and the nest predation rate increased with increasing number of available nests. The predation events started after the mean initiation day of incubation, and coincided with the highest number of available nests. None of the parameters we tested in a logistic regression analysis (physical condition, nest cover, experience and date for initiation of egg-laying) could predict the predation probability of nests and incubating females. However, “good” nest cover tended to have some predictive value on the predation probability. Yearling incubating females had significantly lower physical body condition than adults, and also there were differences in choice of nest site in relation to cover between the two age groups. Initiation of egg-laying in adult females tended to be distributed more evenly over the season, whereas yearling females had a more aggregated egg-laying pattern, compared to adults.

GPS-telemetry as a method to assess nest attendance by a female broad-snouted caiman Caiman latirostris

Crocodylians exhibit parental care, guarding their eggs during incubation to ensure offspring survival. We present the first description of nest attendance of a wild broad-snouted caiman using GPS-telemetry. During the reproductive season of 2022, we tracked a 1.8-metre female in the Tapacurá reservoir, a water source bordered by Atlantic Forest remnants and human settlements in north-eastern Brazil. Telemetry data revealed that 75.8% of the female’s position records were near the nest, suggesting parental care and nest protection. However, the female periodically returned to water. We observed no differences in proximity to the nest between day and night-time, which could be possibly related to different egg predators in the area foraging at different times of the day. Furthermore, the period when the nest was unattended could be associated with either feeding activities or avoidance of human presence. This research brings light on an important part of the reproductive behaviour of broad-snouted caimans in their natural environment, highlighting the importance of GPS-telemetry as a tool for monitoring reproductive behaviour of crocodylians, while contributing to understanding their biology under human-influenced settings. Keywords: Atlantic Forest, crocodylian, movement, parental care, reproductive biology

Host egg volatiles are involved in brood parasitism in predatory mites

Abstract Recently, we reported brood parasitism in the tiny predatory mite Neoseiulus californicus (Acari: Phytoseiidae); adult females of this species prefer to add their eggs to a cluster of eggs of another predatory mite species, Gynaeseius liturivorus (Acari: Phytoseiidae), which guards its own eggs against egg predators. Here, we investigated the cues used by the blind N. californicus to detect eggs of G. liturivorus. We show that N. californicus locates oviposition sites of G. liturivorus using volatiles emanating from eggs of the latter species. Adult female G. liturivorus spent more time guarding oviposition sites that contain more eggs, which resulted in a higher per capita survival of the eggs. We therefore hypothesized that N. californicus would prefer oviposition sites with more G. liturivorus eggs. Indeed, N. californicus preferably laid their egg at oviposition sites containing more than six G. liturivorus eggs, which corresponds to the average number laid by a female G. liturivorus during 1 day. Our results suggest that N. californicus uses egg volatiles to localize oviposition sites of G. liturivorus, where the eggs of the former are effectively protected against egg predators.

Evaluating deterrents to reduce depredation of wood duck eggs in nest boxes

AbstractWood ducks (Aix sponsa) are secondary natural cavity‐nesting species that also nest in artificial nest boxes. Since the early 20th century, nest boxes have been widely deployed in North America to increase nesting sites for wood ducks and bolster production. Equipping nest boxes with a predator guard beneath the box is a common practice to deter climbing predators from accessing boxes; however, there is no device to repel avian predators. We found that eastern rat snakes (Pantherophis alleghaniensis) and woodpeckers (Picidae) were primary predators of wood duck eggs in boxes in North Carolina and South Carolina. Accordingly, we designed experiments to deter snakes and woodpeckers using a commercial brand of snake repellent pellets and a plastic raptor decoy, respectively. Male and female snakes that accessed boxes averaged 1.4 m (SE = 2.0 cm) in length. Digital camera data indicated that snakes climbed nest box posts and thrust their anterior body atop predator guards to continue their ascent into the box. We recorded 671 nest failures of which rat snakes accounted for 39.9% (n = 268) and woodpeckers 22.4% (n = 150). Snakes consumed ≥649 eggs, observed as protuberances in their stomachs. Our experiment showed that commercial snake repellent pellets did not deter snakes (P = 0.957). Placing a plastic hawk decoy atop nest boxes when females were incubating ≥12 days increased nest survival during the incubation stage (P = 0.001). Wood duck nest boxes at our study sites may be experiencing increased nest predation by rat snakes due to poor maintenance and installation of predator guards. Rat snakes and woodpeckers may be depredating wood duck eggs in the southeastern United States at unknown rates, potentially decreasing production and recruitment from these structures.

Effects of road salt, egg predation and alterations to the egg-mass jelly layers on the embryos of spotted salamander Ambystoma maculatum

Road de-icing salt has been used to make winter driving safer. However, its eventual drainage into adjacent water bodies has caused detrimental effects on organisms in those aquatic communities, including amphibians. We used the spotted salamander Ambystoma maculatum as a model species and examined whether there would be additive or interactive effects of road salt, egg predation from wood frog Lithobates sylvaticus tadpoles, and alteration to egg-mass jelly layers on the hatching rate, incubation period, snout-vent length (SVL) and developmental stage of hatchlings. We found neither main nor interactive effects of salt on the measured traits, which contradicts some of the previous studies. The other body of previous studies, however, showed observational and experimental evidence that amphibian populations became locally adapted to saline water. Given the roadside origin of our study animals, our negative results provide insight into the ubiquity of local adaptation to saline water among amphibian populations. We also found that egg predation and the presence of egg-mass jelly layers negatively affected the incubation period, SVL, or development in the predicted manners based on the O2 demand-supply balance within egg masses. These responses might be altered by dissolved salt if populations naive to freshwater salinisation were exposed to saline water. Keywords: aquatic pollution, community ecology, conservation, larval amphibians, Lithobates sylvaticus

Paternal care plasticity: males care more for early- than late-developing embryos in an arboreal breeding treefrog

BackgroundParental care benefits offspring but comes with costs. To optimize the trade-off of costs and benefits, parents should adjust care based on intrinsic and/or extrinsic conditions. The harm to offspring hypothesis suggests that parents should invest more in younger offspring than older offspring because younger offspring are more vulnerable. However, this hypothesis has rarely been comprehensively tested, as many studies only reveal an inverse correlation between parental care and offspring age, without directly testing the effects of offspring age on their vulnerability. To test this hypothesis, we studied Kurixalus eiffingeri, an arboreal treefrog with paternal care. We first performed a field survey by monitoring paternal care during embryonic development. Subsequently, we conducted a field experiment to assess the prevalence of egg predators (a semi-slug, Parmarion martensi) and the plasticity of male care. Finally, we conducted a laboratory experiment to assess how embryo age affects predation by P. martensi.ResultsOur results showed that (1) male attendance and brooding frequency affected embryo survival, and (2) males attended and brooded eggs more frequently in the early stage than in the late stage. The experimental results showed that (3) males increased attendance frequency when the predators were present, and (4) the embryonic predation by the semi-slug during the early was significantly higher than in the late stage.ConclusionsOur findings highlight the importance of paternal care to embryo survival, and the care behavior is plastic. Moreover, our results provide evidence consistent with the predictions of the harm to offspring hypothesis, as males tend to care more for younger offspring which are more vulnerable.

Semi‐natural habitat, but not aphid amount or continuity, predicts lady beetle abundance across agricultural landscapes

Abstract The amount of semi‐natural habitat surrounding farm fields is a common but inconsistent predictor of natural enemy populations and predation services. Standard land cover metrics may not accurately capture the actual availability of limiting resources for natural enemies and can miss important dynamics across space and time. Theory from animal movement and landscape ecology predicts that regions with more, spatio‐temporally continuous resources (i.e. food and shelter) should have larger predator populations and enhanced biological control. To test these predictions empirically, we designed a study measuring aphids, lady beetles and predation services in agricultural landscapes in Wisconsin, USA. In two study years, we sampled lady beetles and aphids in 336 crop fields (corn, soybean, alfalfa and small grains) and adjacent semi‐natural habitat patches (grasslands and woodlands) across 24 1.5 km buffer landscapes at four to seven time points each, and in 1 year, we assessed predation rates with sentinel egg cards. We used aphid counts to model habitat‐specific aphid phenologies, from which we calculated landscape indices of prey amount and continuity. These indices, along with semi‐natural habitat area, were used to predict lady beetle abundance. While there were strong differences in the abundance and timing of aphids by habitat, semi‐natural habitat amount was still a better predictor of lady beetle counts and sentinel egg predation than either aphid amount or continuity indices in these landscapes. Synthesis and applications. Our findings confirm the robust relationship between lady beetles and semi‐natural habitat in agricultural landscapes, and highlight the complexities of measuring fine‐scale resource heterogeneity in real landscapes. Retaining or adding woodland and grassland patches in agricultural landscapes is likely to support larger lady beetle populations and enhance predation in crop fields. Our results suggest that these habitats may be more important for shelter than prey continuity, though this mechanism warrants further investigation. Future work should continue to refine experimental methods for the successful integration of landscape ecology and animal behaviour to support conservation goals.

The evolution of brood parasitism from host egg predation

Abstract Obligate brood parasites pass all their parental duties to foster parents of a host species. While best understood in birds and hymenopteran insects, obligate brood parasitism has evolved independently at least 59 times across many lineages. The ancestors of brood parasites often provided no parental care to their offspring. Instead, a trophic association with their eventual hosts commonly appears to precede the origin of a brood parasitic strategy. Here, we used a game theoretical model to explore the conditions under which brood parasitism can evolve from predation and be maintained in the population. Our model was inspired by the relationship between the cuckoo catfish (Synodontis multipunctatus) parasitizing mouthbrooding cichlid fishes in the African Lake Tanganyika. Our model demonstrates the facilitatory role of host egg predation on the origin and evolutionary maintenance of brood parasitism through the exploitation of the host response to egg predation by brood parasites. We found no conditions under which brood parasitism as a pure strategy is evolutionarily stable, but we describe a range of evolutionarily stable equilibria when predators and parasites coexist. While our model is tailored to the cuckoo catfish, it generally applies to other systems where brood parasitism has evolved from other antagonistic behavior.

The effects of intensive trapping on invasive round goby densities.

The round goby (Neogobius melanostomus) is an invasive benthic fish first introduced to the Laurentian Great Lakes in 1990 that has negatively impacted native fishes through increased competition for food and habitat, aggressive interactions, and egg predation. While complete eradication of the round goby is currently not possible, intensive trapping in designated areas during spawning seasons could potentially protect critical native fish spawning habitats. Baited minnow traps were spaced 10 meters apart in shallow water along a 100-meter stretch of shoreline within the Duluth-Superior Harbor during the round goby breeding period (June to October) with captured round gobies removed from interior traps (N = 10) every 48 hours. These traps were bracketed by two pairs of reference traps deployed weekly for 48 hours, from which round gobies were also tagged and released. The number of round gobies captured in the interior traps declined by 67% compared to reference traps over the course of the study, with extended periods of no captures. The tagged round gobies showed high site affinity, with 82.8% of tagged fish recaptured at the previous release site. The results indicate that even at open water sites, which allow natural migration of round gobies into the area, extensive trapping could reduce local population numbers.

Exploring the impact of biocontrol and temperature variations on the population dynamics of Paracoccus marginatus

The mealybug (Paracoccus marginatus) is one of the most important pests of papaya (Carica papaya L.). The high potential damage of this pest threatens papaya production. The objective of this paper is to explore the impact of biocontrol and temperature variations on the population dynamics of Paracoccus marginatus (P. marginatus). We first propose and study a mathematical model for the dynamics of P. marginatus within a papaya field. This model consists of a time-delayed non-autonomous system of differential equations that takes into account the egg incubation period, temperature variations, plant compensation and predators that are natural enemies of the papaya pest. We provide the basic properties of the model, compute the basic offspring number N0 and show that there exists two threshold parameters N_0 and ξ0 such that N_0≤N0≤ξ0≤1 and N0≥N_0>1 provide conditions for the extinction and persistence of the pest within the papaya field, respectively. After, we investigate the impact of biocontrol on the pest population. We found that the use of a control strategy based on constant releases of predators could reduce the pest population by 35.62 percent and increase the biomass by 77.50 percent, while the use of impulsive releases of predators result in a decrease of 96.31 percent of the pest population and an increases of 55.74 percent of the biomass. We also combine the use of continuous predator releases and bio-pesticides and discovered that a spray applied 90 days after germination could completely eliminate the pest population and boost the biomass by 81.58 percent.

Sister predatory mites collectively protect their eggs against predators.

Group-living animals sometimes cooperatively protect their offspring against predators. This behavior is observed in a wide range of taxa but, to the best of our knowledge, this is the first report of its occurrence in arthropods that are not eusocial. Adult female predatory mites Gynaeseius liturivorus protect their eggs against egg predators, the predatory mite species Neoseiulus californicus. In the field, several adult female G. liturivorus were often found on the same plant structures such as folded leaves. We tested whether these females might protect their eggs cooperatively, focusing on kinship between the females. When two adult female G. liturivorus were kept in the absence of egg predators, their reproduction was not affected by their kinship. The presence of egg predators reduced the number of G. liturivorus eggs. However, reproduction of two G. liturivorus sisters was higher than that of two non-sisters. Together, sisters guarded the oviposition site longer than non-sisters. We further tested if non-sisters increased egg guarding by having developed together from eggs to adults and found no such effect. Although it remains unclear how adult female G. liturivorus recognize conspecifics as kin or sisters, our results suggest that G. liturivorus sisters reduced predation on their offspring by cooperatively guarding their eggs.

Molecular barcoding reveals patterns of egg predation in small pelagic fish

Cannibalism and intraguild predation occur in a vast number of small pelagic fish (SPF) species. Egg and larval predation can have important consequences on mortality, and its accurate assessment is important to estimate the impact on recruitment strength and population dynamics of predators and prey. Such assessments are hampered by limitations in visual species identification of many fish eggs and larvae in the predators’ stomachs. European sardine Sardina pilchardus and Atlantic chub mackerel Scomber colias, the dominant species of the pelagic food web off the Canary Current Upwelling ecosystem, are major predators of fish eggs. Egg predation by these SPF species is particularly high on sardine and anchovy eggs, but many preyed fish eggs are not amenable to visual identification. This study provides a proof-of-concept application of molecular identification of diverse fish eggs from SPF stomach contents not suitable for visual identification, as a way to improve our understanding of the impact of intraguild predation on fish population dynamics. Results show a high diversity of fish species in the eggs ingested by sardines and chub mackerel (18 and 15 families, respectively), mostly comprising locally abundant coastal taxa. Sardine ingested predominantly anchovy, sardine and sparid eggs, while chub mackerel ingested predominantly sparid eggs, followed by serranid (Serranus spp.) and sardine eggs. Sardines also showed higher variability in prey composition compared to chub mackerel. Exploratory analyses also suggested variability in prey composition with sampling area, season and maturity stage for sardine and chub mackerel, highlighting the need for dedicated follow-up studies.

Brood protection is essential but not sufficient for population survival of lapwings Vanellus vanellus in central Switzerland

Lapwing are among those ground nesting bird species that suffered strong population declines following agricultural intensification in many parts of Europe. The key problem appears to be a low breeding success which, depending on the situation, may be due to predation of eggs and chicks, starvation of chicks especially during dry conditions, agricultural activities leading to direct killings, and suboptimal breeding habitat. Here, we report on a population of 40–60 lapwing breeding pairs in an intensively cultivated arable landscape in central Switzerland, where protection from farming activities, implementation of special lapwing habitat and nest fencing to exclude terrestrial predators (mainly red fox) started in 2005 and is still ongoing. Chicks were ringed and families subsequently observed every 2–3 days. Hatching success for fenced nests built before May was high. Low hatching success was observed in unfenced nests due to high predation rates and in late nests due to abandonment by the female when the vegetation was growing too tall (e.g. maize). Regularly, chicks disappeared during the night shortly after hatching. Most likely many of them first left the fence and were predated outside. Our observations from a fenced field with wet soils and puddles suggest that lapwing may produce sufficient offspring if predation can be reduced and if large enough areas with suitable habitat are available.

Nesting trends and predation risks among yellow-spotted river turtles in Essequibo River Basin

The yellow-spotted river turtle (Podocnemis unifilis), inhabiting Amazon, Orinoco, and Essequibo River basins, is classified as vulnerable due to historical exploitation and current threats. Efforts have been made throughout the Amazon basin to understand the ecology of yellow-spotted river turtles and implement conservation measures, but the Essequibo River basin located in Guyana, remains the least studied part of the geographical range of the species. In this study we present data collected over a three-year period from 2020 to 2023, as part of a community driven conservation program by Yupukari village, in the North Rupununi, Guyana. We describe the nesting behavior of P. unifilis,and assess predation of eggs in the wild. A total number of nests in 9 beaches ranging from 59 (in 2021) to 76 (in 2023) (in averge 6.68 nest/beach, and 14.2 nests per ha) with an average number of 20.45 eggs per nest. Nesting locations were found to be predominantly situated within 1–20 m from the river, in proximity to vegetation, and on fine sand, with temperatures consistently falling within the 27–29 degrees Celsius range. Importantly, this study unravels the critical issue of nest predation, with lizards, human, and the birds emerging as the primary culprits, impacting nests located closer to vegetation to a greater extent. All nests in sites which potentially would be flooded were moved for a hatchery in the community of Yupukari in which the hatching success reached 83%.

Invasive Round goby Neogobius melanostomus distribution, relative abundance, and establishment in pools of the Illinois Waterway following 30 years of invasion

Round goby Neogobius melanostomus – a small, benthic fish native to Eurasia – was first introduced to North America in the 1980s through ballast water of cargo ships. In 1990, the Round goby was first discovered in the Laurentian Great Lakes Basin and rapidly spread through all Great Lakes from 1993 to 1998. The Round goby is an aggressive, prolific, and efficient egg predator that subsequently displaced native fishes from their preferred habitats and resources in the Great Lakes, where they are well established and abundant. From Lake Michigan, Round goby moved south into the Chicago Area Waterway System in 1993 and slowly progressed down the Illinois Waterway to the Mississippi River from 2004 to 2019, where less is known about their abundance, establishment, and impact. The goal of this study was to gain a comprehensive understanding of the first large river invasion by Round goby in the Mississippi River Basin by leveraging Round goby capture data from 2019 to 2022 on all pools of the Illinois Waterway. We describe their current distribution, relative abundance (i.e., catch-per-unit-effort), frequency of occurrence, and establishment (i.e., presence of young-of-year and adults) status throughout the Illinois Waterway. Results show that catch-per-unit-effort, frequency of occurrence, and the proportion of sites where multiple life stages are present are considerably higher in the upstream pools relative to more downstream pools of the Illinois Waterway. Our data support that the Round goby has established self-sustaining populations in the Chicago Area Waterway System, the upper Illinois River (i.e. Dresden Island Pool downstream through Starved Rock Pool), and a portion of the lower Illinois River (i.e. Peoria Pool downstream through Alton Pool) of the Illinois Waterway. In the lower Illinois River, Round gobies appear to only be established in Peoria Pool, with captures occurring infrequently in La Grange Pool, and no Round gobies being captured in Alton Pool.

Local Habitat Complexity and Its Effects on Herbivores and Predators in Urban Agroecosystems.

In urban community gardens, cultivated vegetation provides variable levels of habitat complexity, which can suppress pests by promoting predator diversity and improving pest control. In this study, we examine three components of the structural complexity of garden vegetation (cover, diversity, and connectivity) to investigate whether higher garden vegetation complexity leads to fewer herbivores, more predators, and higher predation. We worked in eight community gardens where we quantified vegetation complexity, sampled the arthropod community, and measured predation on corn earworm eggs. We found that plots with high vegetation cover supported higher species richness and greater abundance of predatory insects. High vegetation cover also supported a greater abundance and species richness of spiders. In contrast, high vegetation diversity was negatively associated with predator abundance. While high predator abundance was positively associated with egg predation, greater predator species richness had a negative impact on egg predation, suggesting that antagonism between predators may limit biological control. Community gardeners may thus manipulate vegetation cover and diversity to promote higher predator abundance and diversity in their plots. However, the species composition of predators and the prevalence of interspecific antagonism may ultimately determine subsequent impacts on biological pest control.