Exotic Ladybird Research Articles

Fight and rescue or give up and flee? Behavioural responses of different ant species tending the mutualist walnut aphid Panaphis juglandis to native and exotic lady beetles - CORRIGENDUM.

Fight and rescue or give up and flee? Behavioural responses of different ant species tending the mutualist walnut aphid Panaphis juglandis to native and exotic lady beetles - CORRIGENDUM.

Fight and rescue or give up and flee? Behavioural responses of different ant species tending the mutualist walnut aphid Panaphis juglandis to native and exotic lady beetles.

Mutualism between ants and honeydew-producing hemipterans is a highly successful evolutionary innovation that attains the status of ecological keystone across many terrestrial ecosystems, involving a multitude of actors through direct or cascading effects. In these relationships, ants often protect their hemipteran partners against their arthropod natural enemies, sometimes interfering with the biological control of pest species. However, the dynamics of these interactions are highly variable based on the specific identity of all the actors involved, and baseline data remain scarce. We performed a field experiment exposing colonies of the walnut aphid Panaphis juglandis attended by five European ant species (Camponotus piceus, Ca. vagus, Crematogaster scutellaris, Dolichoderus quadripunctatus, Lasius emarginatus) to a native and an exotic lady beetle (Adalia bipunctata and Harmonia axyridis), documenting the behavioural interactions between these insects and the performance of ants in the protection of the aphids. Our results reveal a significant behavioural diversity among the ant species involved, with D. quadripunctatus and L. emarginatus being the most aggressive and having the best performance as aphid defenders, and Ca. piceus being least effective and often fleeing away. Cr. scutellaris displayed a rare rescue behaviour attempting to pull away the aphids that the lady beetles grabbed. On the other hand, behavioural responses to A. bipunctata and H. axyridis were similar. Further investigations are needed to understand the eco-ethological implications of these differences, while a better understanding of ant behavioural diversity may help refine biological control strategies.

Coexistence between similar invaders: The case of two cosmopolitan exotic insects.

Biological invasions are usually examined in the context of their impacts on native species. However, few studies have examined the dynamics between invaders when multiple exotic species successfully coexist in a novel environment. Yet, long-term coexistence of now established exotic species has been observed in North American lady beetle communities. Exotic lady beetles Harmonia axyridis and Coccinella septempunctata were introduced for biological control in agricultural systems and have since become dominant species within these communities. In this study, we investigated coexistence via spatial and temporal niche partitioning among H. axyridis and C. septempunctata using a 31-year data set from southwestern Michigan, USA. We found evidence of long-term coexistence through a combination of small-scale environmental, habitat, and seasonal mechanisms. Across years, H. axyridis and C. septempunctata experienced patterns of cyclical dominance likely related to yearly variation in temperature and precipitation. Within years, populations of C. septempunctata peaked early in the growing season at 550 degree days, while H. axyridis populations grew in the season until 1250 degree days and continued to have high activity after this point. C. septempunctata was generally most abundant in herbaceous crops, whereas H. axyridis did not display strong habitat preferences. These findings suggest that within this region H. axyridis has broader habitat and abiotic environmental preferences, whereas C. septempunctata thrives under more specific ecological conditions. These ecological differences have contributed to the continued coexistence of these two invaders. Understanding the mechanisms that allow for the coexistence of dominant exotic species contributes to native biodiversity conservation management of invaded ecosystems.

Apparent niche differences between native and exotic lady beetles

Generalist predators can enhance biological control by filling unique niches and complementing other natural enemies, or disrupt it by preying upon other predators and parasitoids, complicating their net value for biological control. We searched for evidence of complementarity and/or interference between native (primarily Eriopis chilensis and E. eschscholtzi) and exotic (primarily Hippodamia variegata and Harmonia axyridis) lady beetles attacking aphids in alfalfa (Medicago sativa) fields near Santiago, Chile. Across 60 fields and three growing seasons, exotic lady beetle adults and larvae reached peak abundance relatively earlier in the growing season than the natives. Furthermore, exotic lady beetle peaks aligned more closely with aphid peak abundance than did native lady beetle peaks. Abundances of native lady beetle adults and larvae were weakly positively correlated with those of exotics, and peak aphid densities were generally lowest in fields where native and non-native lady beetle adults were similarly abundant. Therefore, we did not see evidence of strong interference between exotics and natives. Natural-agricultural habitat edges reduced native, but not exotic, larval lady beetle lag behind aphid peaks and was associated with greater lady beetle and lower aphid densities. Moreover, farms embedded in landscapes with greater natural habitat cover supported more exotic, but not native, lady beetles, and increased the lag between larval lady beetles and aphids for natives but not exotics. These findings support the idea that farms embedded within mosaics of natural and agricultural habitats may provide greater interaction potential between native lady beetles and aphid pests on farms as they move across the landscape, leading to greater top-down control. In contrast, exotic lady beetle lags were unaffected by landscape composition or configuration, but their greater densities in farms surrounded by more natural habitats might reflect a 'concentration effect' whereby exotic lady beetle abundance becomes concentrated in the agricultural habitats that they prefer. Our findings suggest that some lady beetles introduced for biocontrol may be better adapted to intensively managed habitats than natives, possibly leading to spatiotemporal complementarity between native and exotic lady beetles.

Apparent Niche Differences between Native and Exotic Lady Beetles

Apparent Niche Differences between Native and Exotic Lady Beetles

Interactions between exotic and native lady beetle species stabilize community abundance.

A 23-year time-series of abundance for 13 lady beetle species (Coccinellidae) was used to investigate community stability. The community exhibited persistence in ten habitats, no overall trend in abundance, and low temporal variability quantified as Population variability (PV) = 0.33 on a scale from 0 to 1 that declined to 0.16 in the past 8years. This high level of stability occurred as exotic lady beetles disrupted populations of the native species. For hypothetical communities of pairs of species (with randomly generated annual abundances in the range for lady beetles), PV increased linearly with the correlation coefficients between individual time series, illustrating a "portfolio effect". PV for the real community and the negative correlation between the abundance of exotics and natives fit this relationship precisely. A gradual decline of natives matched by an equal gradual rise in the abundance of exotics contributed to the negative correlation that stabilized the community. The abundance of the dominant species, an exotic, was negatively correlated with other exotics and most natives, and its stability increased over time, helping to stabilize the community. The community was most stable in habitats where beetle abundance was high (crops, particularly perennial crops) and, unexpectedly, was least stable in habitats with high diversity and stability of vegetation cover (forests). These data are consistent with the hypothesis that competition between exotic and native species, with release from competition for natives in some years, stabilized the abundance of this community. Stability may not last if populations of native species continue declining.

Landscape Context Influences the Abundance and Richness of Native Lady Beetles Occupying Urban Vacant Land

Urban insect communities are structured by hierarchical filters including regional processes, human facilitation, and species interactions. We sought to inform future urban conservation endeavors by identifying how landscape composition and configuration as well as the management of vacant lot greenspaces affect native lady beetle (Coccinellidae) community structure within the city of Cleveland, Ohio, USA. We found no effect of habitat treatment on native lady beetle abundance when comparing vacant lots seeded with native wildflowers and those with naturally occurring weedy vegetation mown monthly or annually. Nonetheless, establishing conservation plantings that vary in plant height, biomass, and bloom abundance could aid in supporting a greater richness of coccinellid species, as these variables had differential effects on the abundance of fungivorous and aphidophagous feeding guilds. Further, we found that vacant lots embedded within landscapes with increased impervious surface and a high degree of greenspace isolation contained fewer aphidophagous native and exotic lady beetles. Our findings suggest that landscape context is a critical consideration when aiming to utilize vacant land as conservation habitat for coccinellids. Given their large holdings of vacant land, shrinking cities offer a unique opportunity to incorporate landscape-scale planning into future sustainable development initiatives. For instance, with over 27,000 vacant lots, the city of Cleveland could aid lady beetle conservation by electing to maintain vacant lots that promote greenspace connectivity while targeting isolated lots within intact neighborhoods for new residential development.

Stability of native and exotic lady beetle populations in a diverse landscape

AbstractThe stability of populations is a central, yet challenging concept in ecology. Here, we examine the stability of annual abundance for populations of nine native and four exotic lady beetle species (Coccinellidae) in a mixed landscape in Michigan, USA, over 23 yr. The species have similar life histories, live together in the same habitats, and have been disturbed by the sequential introduction of exotic lady beetle species. The publicly available dataset was collected in a diverse landscape of three forest habitats, four annual crop habitats with different intensities of management, and three perennial crops. Replicated 1‐ha plots were sampled weekly with yellow sticky cards during the summer season for each habitat, three plots for each of the three forest types and six plots for each of the seven crop habitats. We quantified stability for each species and each species by habitat combination, using three parameters: trends in abundance, persistence, and temporal population variability. The most abundant lady beetle species were more stable than the uncommon and rare species. Habitat generalists had more stable population dynamics than specialists, but habitat breadth was confounded with lady beetle abundance. Exotic and native species with similar abundances had similar levels of stability. Exotic species disrupted the native populations, leading to declines in abundance for eight of nine species and increased population variability for the native species. The abundances of exotic lady beetles rose quickly to the long‐term mean. Our findings support the hypothesis that populations exhibit species‐specific levels of stability, not greatly affected by stochastic variations in environmental conditions or by habitat characteristics. We also show that exotic species can decrease the stability as well as the abundance of native species in a community of lady beetles.

Larvae of the exotic predatory ladybird Platynaspidius maculosus (Coleoptera: Coccinellidae) on citrus trees: prey aphid species and behavioral interactions with aphid-attending ants in Japan

An aphidophagous ladybird, Platynaspidius maculosus (Weise) (Coleoptera: Coccinellidae), is originally distributed in China, Taiwan, and Vietnam. The ladybird has recently intruded into the southern and central parts of Japan. The present study found that the larvae of this ladybird preyed on three aphid species, Aphis spiraecola, Aphis gossypii, and Toxoptera citricidus (all Hemiptera: Aphididae), feeding on young shoots of various Citrus species in August to early October in Shizuoka Prefecture, central Japan. Laboratory rearing of the sampled larvae confirmed that the larvae completed their development (adult emergence) by consuming each of the three aphid species. The ladybird larvae were observed foraging in aphid colonies attended by one of the four ants, Lasius japonicus, Pristomyrmex punctatus, Formica japonica, and Camponotus japonicus (all Hymenoptera: Formicidae). Field observations revealed that the foraging/feeding larvae were almost completely ignored by honeydew-collecting ants even when they physically contacted each other. Thus, in Japan, the larvae of the exotic ladybird exploit colonies of the three aphid species attended by one of the four ant species on many Citrus species. On the basis of the results, I discuss the possibility of the ladybird’s reproduction on citrus trees in Japan, probable adaptations of the ladybird larvae to aphid-attending ants, and potential impacts of the ladybird on native insect enemies attacking ant-attended aphids on citrus.

The ExoticHarmonia axyridis(Pallas) (Coleoptera: Coccinellidae) and Other Coccinellids in Selected Vineyards of the Western Cape Province, South Africa

Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is an exotic ladybird, first recorded in South Africa in 2004, where it was introduced factitiously. In this study the seasonal occurrence of H. axiridis and other coccinellids were monitored in four vineyards and the adjacent windbreaks over three growing seasons in the Western Cape Province, South Africa. Harmonia axyridis made up the highest mean number of coccinellids collected per site over the collecting period, followed by Hippodamia variegata, Cheilomenes lunata, Exochomus flavipes and Micraspis sp. No indigenous parasitoids were observed attacking H. axyridis. The numbers of H. axyridis on the vines were negatively correlated with temperature but positively with rainfall. In view of the migration of H. axyridis from the vines in December, they appear not to pose any risk of contaminating grapes during harvest and tainting wine as most wine grapes are harvested from January onwards.

Integrating spatially explicit molecular and ecological methods to explore the significance of non-crop vegetation to predators of brassica pests

There is mounting evidence that non-crop vegetation can promote natural enemies of crop pests but most studies use only one or a few approaches to explore key processes. Here we integrate field sampling, insect marking, insecticide disruption, and molecular gut content analysis to explore the potential value of non-crop habitats to predators of brassica pests in temperate Australia. Twelve monthly surveys of 13 farms established that an exotic ladybird (Hippodamia variegata) and a native lacewing (Micromus tasmaniae) were numerically dominant predatory arthropod species in brassica crops and present in adjacent perennial pasture, bushland and riparian vegetation. We applied dye to non-crop vegetation on three sites and subsequently sampled predators from adjacent brassica crops. Relatively large proportions of H. variegata and M. tasmaniae were marked, especially close to the non-crop vegetation though also extending 100m into the crop, indicating predator immigration into the crop. In a third study, predators were monitored in three brassica crops after the host farmers sprayed insecticide to control what they considered to be excessive pest densities. Within two days, H. variegata and M. tasmaniae adults were present in the crops and numbers increased significantly over 12days showing rapid crop recolonisation. Finally, molecular gut analysis indicated large proportions of both predator species sampled from non-crop (non-brassica) vegetation contained DNA of brassica-specialist herbivores suggesting predator movement from crop to non-crop vegetation, possibly to access nectar. Findings demonstrate H. variegata and M. tasmaniae are likely to be important predators of brassica pests in the region and expand our understanding of the significance of non-crop vegetation for coccinellids and lacewings.

Interspecific relationship between an exotic ladybird beetle ， Adalia bipunctata (Linnaeus) (Coleoptera: Coccinellidae) ， and native predacious ladybird beetles

Interspecific relationship between an exotic ladybird beetle ， Adalia bipunctata (Linnaeus) (Coleoptera: Coccinellidae) ， and native predacious ladybird beetles

The Influence of Exotic Lady Beetle (Coleoptera: Coccinellidae) Establishment on the Species Composition of the Native Lady Beetle Community in Missouri.

The diversity and abundance of native lady beetles (Coccinellidae) in North America has declined in recent decades. This decline is often correlated with the introduction and establishment of exotic lady beetle species, including Coccinella septempunctata L. and Harmonia axyridis Pallas, suggesting that exotic species precipitated the decline of native lady beetles. We examined species records of native coccinellids in Missouri over 118 yr and asked whether the species composition of the community experienced a shift following the establishment of the exotic species. We found that the contemporary native coccinellid community is different from the community that was present nearly a century ago. However, there was no evidence for a recent abrupt shift in composition triggered by the establishment of exotic species. Instead, our data suggest that the native lady beetle community has been undergoing consistent and gradual change over time, with some species decreasing in abundance and others increasing. While not excluding exotic species as a factor contributing to the decline of native lady beetle species, our findings suggest that other continuous factors, like land use change, may have played a more influential role in determining the composition of the native coccinellid communities within our region.

Refuge for native lady beetles (Coccinellidae) in perennial grassland habitats

The proportion of native individuals in North American lady bee- tle communities has declined precipitously over the past 30 years, particularly in annual cropping systems. At the same time, the number and abundance of exotic coccinellid species have been on the rise as beetles are introduced both inadvertently and intentionally for the purposes of biological control. 2. Perennial grasslands have been proposed as refuge habitats that promote native lady beetles, either by resisting the invasion of exotics or by providing a consistent source of shelter and resources. 3. Our objective is to compare the conservation value for native lady beetles of different perennial grassland habitats that vary in their degree of habitat modification and disturbance. 4. The abundance, species richness, and species composition of native and exotic lady beetles were compared across remnant native tallgrass prairies, native tallgrass prairies actively restored from cultivation and exotic tall fescue grasslands grown as forage crops. 5. Native species dominated the lady beetle community in all perennial grass- land habitats, with more than 95% of captured individuals being native in ori- gin. Exotic lady beetle species were equally rare across all habitat types. 6. The grassland habitat considered the most disturbed, agriculturally grown exotic tall fescue, had the highest abundance and species richness of native lady beetles and a unique composition of species as compared to prairie habitats. Lady beetle communities in remnant and restored tallgrass prairies were indistinguishable, indicating that prairie restoration successfully re-established coccinellid communities. 7. Promoting perennial grasslands, both natural and agricultural, within disturbed landscapes has the potential to enhance native lady beetle populations.

Occurrence of the exotic predatory ladybird Platynaspidius maculosus (Coleoptera: Coccinellidae) in citrus groves in Shizuoka City, Central Japan: seasonal prevalence of adults captured on sticky traps

Platynaspidius maculosus (Weise, 1910) (Coleoptera: Coccinellidae) is a ladybird beetle that preys on aphids and is distributed in China, Taiwan, and Vietnam. Recently, P. maculosus has invaded the southern parts of Japan; it was recorded on Okinawa Island in 1998, in Kagoshima Prefecture in 2006, and in Fukuoka Prefecture in 2010. In citrus groves in Shizuoka City, Central Japan in 2009–2012, the exotic ladybird was monitored by use of yellow sticky traps set inside citrus tree canopies. Adults of P. maculosus were captured in three out of the eight groves in 2010. This capture might be the first record of the ladybird from Honshu Island. Adults were trapped in three consecutive years, 2010–2012, in two groves; this suggests the possibility that the ladybird has become established in Shizuoka City. Adults were almost continuously caught on the traps from late April through October, being more abundant in early autumn (early September to early October), late spring (late April to mid-June), and mid-summer (early July to early August). During these periods, citrus shoots are growing and aphids are abundant. This finding suggests that the exotic ladybird might prey on citrus-infesting aphids, thereby reproducing in citrus groves. Based on the results obtained, potential impacts of the exotic ladybird on native aphidophagous ladybirds are also discussed.

Intraguild interactions and aphid predators: biological efficiency of Harmonia axyridis and Episyrphus balteatus

AbstractIntroductions of the harlequin ladybird Harmonia axyridis into Belgium for aphid biological control have been followed by declines in native aphid natural enemies. We first examined, in laboratory and field conditions, the impact of larval mobility of either H. axyridis or Episyrphus balteatus, the most abundant native hoverfly in central Europe, on aphid suppression. The hoverfly larvae consumed more aphids (Megoura viciae) in a short term, whereas the ladybird ones were more efficient in a long term. We second investigated the intraguild interactions between H. axyridis and E. balteatus larvae and adults. In larva pairings between the two species in laboratory microcosms containing aphid (M. viciae) infested broad bean (Vicia faba) plants, H. axyridis had an intraguild predation (IGP) advantage over the hoverfly. When conspecific larvae were paired together on aphid‐infested plants, no cannibalism between them was detected. The presence of either H. axyridis or E. balteatus larvae on aphid‐infested plants negatively influenced the ovipositional behaviour of H. axyridis and E. balteatus females; lower numbers of laid eggs were recorded compared to control treatment. Moreover, eggs laid by E. balteatus females were also dropped as victims of predation mainly by H. axyridis larvae. Our results suggest that while the exotic ladybird was more efficient in aphid biological control, larvae and eggs of the native hoverfly species face increased IGP by H. axyridis, which would contribute, as a consequence, to the decline in E. balteatus population following invasion.

Landscape composition influences patterns of native and exotic lady beetle abundance

AbstractAim Coccinellid beetles are important predators that contribute to pest suppression in agricultural landscapes. Since the introduction of the exotic coccinellids Coccinella septempunctata L. and Harmonia axyridis Pallas into the USA, several studies have reported a decline of native Coccinellidae in agroecosystems. We aimed to investigate the influence of landscape composition on native and exotic coccinellid abundance within soybean fields.Location Iowa, Michigan, Minnesota and Wisconsin.Methods As part of a 2‐year study (2005–06) on the biological control of the soybean aphid, Aphis glycines Matsumura, we examined coccinellid communities in 33 soybean fields using yellow sticky card traps. Landscape heterogeneity and composition were measured at multiple spatial scales ranging 1–3.5 km from focal soybean fields where coccinellid sampling took place.Results Exotic species made up 90% of the total coccinellid community in Michigan soybean fields followed by Wisconsin (84%), Minnesota (66%) and Iowa (57%). Harmonia axyridis was the dominant exotic coccinellid in all states comprising 45–62% of the total coccinellid community, followed by C. septempunctata (13–30%). Two additional exotic species, Hippodamia variegata (Goeze) and Propylea quatuordecimpunctata (L.) were also found in the region. Overall, the most abundant native coccinellid was Hippodamia convergens Guerin‐Meneville; however, its abundance varied across the region, comprising 0% (Michigan) to 28% (Iowa) of the total coccinellid community. Landscape structure significantly influenced the composition of coccinellid communities in soybean agroecosystems. We found that native coccinellids were most abundant in low‐diversity landscapes with an abundance of grassland habitat while exotic coccinellids were associated with the abundance of forested habitats.Main conclusion We propose that grassland dominated landscapes with low structural diversity and low amounts of forested habitat may be resistant to exotic coccinellid build‐up, particularly H. axyridis and therefore represent landscape‐scale refuges for native coccinellid biodiversity.

Estimation of mortality by entomophages on exotic Harmonia axyridis versus native Adalia bipunctata in semi-field conditions in northern Italy

A semi-field experiment was carried out in two peach orchards in northern Italy to assess mortality due to predators and parasitoids on the exotic coccinellid Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in comparison with the native coccinellid Adalia bipunctata L. (Coleoptera: Coccinellidae). The experiments were conducted in cages to avoid the possible escape of the exotic ladybird (not yet established in Italy). Two kinds of cage experiments were included: ‘exclusion cages’ (access by walking predators impeded) and ‘free cages’ (walking predators free to enter). The cages, containing all the stages of the two ladybird species, were placed in two localities and left for 24 h. All ladybird stages used for the semi-field experiments came from a laboratory rearing. The eggs of H. axyridis experienced less mortality than those of A. bipunctata. The ant workers were the most frequent predators in ‘free cages’ but A. bipunctata cannibalism on eggs was also detected. Larvae of both coccinellid species were predated equally but larval predation of L1 and L2 was higher in comparison to predation of L3 and L4. Pupae and adults of both exotic and native ladybirds were never attacked by predators. Predation on younger larval stages was higher in the ‘free cages’ in comparison with ‘exclusion cages’. No ladybird parasitisation was observed. The ‘free cage’ technique seems to provide a standardised and realistic estimation of predation impact but more studies are needed to evaluate ladybird parasitisation in semi-field conditions.

Citizen scientist rediscovers rare nine-spotted lady beetle, Coccinella novemnotata, in eastern North America

A single adult Coccinella novemnotata (the nine-spotted lady beetle) was recently discovered by a Cornell University student amongst a series of specimens collected in early October 2006 in Arlington, Virginia. The specimen is the first individual collected in eastern North America in over fourteen years and is only the sixth of its species known to be collected anywhere in North America in the last ten years. This discovery reopens questions regarding the current status of this once common species. Interactions with exotic species, global climate change, and shifting land use patterns have all been postulated as possible factors in this species decline. This discovery is the first in a new program in the USA designed to educate the public regarding biodiversity and conservation and to engage them in a survey of native and exotic lady beetle species.

Predation by Adult and Larval Lady Beetles (Coleoptera: Coccinellidae) on Initial Contact with Lady Beetle Eggs

Naïve adults and larvae of the native lady beetles Coleomegilla maculata (DeGeer), Cycloneda munda (Say), Hippodamia convergens Guérin-Méneville, Olla v-nigrum (Mulsant), and the exotic lady beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) were tested for their initial response to eggs of these five lady beetle species and for egg consumption on first contact and after 3 h. Additionally, field-collected O. v-nigrum and H. axyridis adults were tested. C. maculata, H. axyridis, and O. v-nigrum adults responded similarly to all egg species on first contact. Higher numbers of C. munda adults did not eat C. maculata, H. convergens, and O. v-nigrum eggs on first contact compared with numbers that did eat C. munda and H. axyridis eggs. H. convergens adults always ate C. munda eggs but hardly ate H. axyridis eggs on first contact. Results showed that over the 3-h interval, egg predation by those predators feeding on first contact was always higher, except for adults and larvae of C. maculata, than for those that did not feed on first contact. Thus, acceptance of eggs on initial contact does impact egg survival. It is likely that eggs of all native species tested (i.e., C. maculata, C. munda, H. convergens, and O. v-nigrum), but not exotic H. axyridis eggs, are suitable food for C. maculata, H. convergens, and O. v-nigrum, whereas only C. munda eggs serve as suitable food for C. munda. In direct contrast, all egg species tested would likely serve as suitable food for the exotic H. axyridis.