Effect of intraguild predation on the survival and development of three species of aphidophagous ladybirds: consequences for invasive species

Abstract 1 Survival and development of hatchling larvae of three aphidophagous ladybirds (Coleoptera: Coccinellidae), Harmonia axyridis Pallas, Coccinella septempunctata brucki Mulsant and Adalia bipunctata Linnaeus, when fed their own and the other species eggs were recorded. 2 In all three species, the larvae survived when fed conspecific eggs. 3 The percentage of larvae of H. axyridis that survived decreased to 35% and 85% when fed eggs of A. bipunctata and C. s. brucki, respectively. All the larvae of A. bipunctata and C. s. brucki died after eating eggs of H. axyridis. None of the larvae of C. s. brucki died after eating eggs of A. bipunctata, whereas 46% of those of A. bipunctata died after eating eggs of C. s. brucki. 4 In general, larvae were reluctant to eat the eggs of other species. However, larvae of C. s. brucki showed less reluctance than H. axyridis to eat the eggs of A. bipunctata. 5 The consequence of this for invasive species of ladybird is discussed.     

越冬代七星瓢虫和异色瓢虫的飞翔能力

在室内用飞行磨吊飞技术测定了七星瓢虫和异色瓢虫越冬代自然种群的飞翔能力。个体间飞翔特性差异极大。36.5%的七星瓢虫和23.7%的异色瓢虫每次飞翔都不到30分钟, 而这两种瓢虫中都有累计飞翔20小时以上的个体。最长持续飞翔时间达8小时以上和12小时以上的个体在七星瓢虫中分别为9.4%和1.2%, 在异色瓢虫中分别为21.1%和13.2%。大于30分钟的飞翔累计时间为6小时以上和12小时以上的个体在七星瓢虫中分别为20.0%和7.1%, 异色瓢虫则达47.4%和28.9%。雌性个体在卵发育期间表现出很强的飞翔能力。吊飞124小时, 飞翔能力的最高纪录是, 七星瓢虫累计飞翔22小时27分, 飞翔距离94.464km;异色瓢虫为24小时, 92.550km;飞翔速度都达到2m/秒。     

Vulnerability of larvae of two species of aphidophagous ladybirds, Adalia bipunctata Linnaeus and Harmonia axyridis Pallas, to cannibalism and intraguild predation

Vulnerability of larvae of two species of aphidophagous ladybirds, Adalia bipunctata Linnaeus and Harmonia axyridis Pallas, to cannibalism and intraguild predation was assessed in the laboratory. In the first experiment, a first instar of one of the two above species was kept with a fourth instar of the other species in a Petri dish. The number of times each first instar larva was encountered by the fourth instar larva and the fate of the first instar was determined over a period of 10 min. The fourth instar larvae captured and killed all the first instar larvae of their own species at the first encounter. However, when presented with fourth instar larvae of the other species the first instar larvae of A. bipunctata and H. axyridis were encountered 6.4 ± 1.3 ( n  = 10) and 19.4 ± 2.1 ( n  = 10), respectively. In this experiment no first instar larvae of H. axyridis , whereas all those of A. bipunctata , were killed.     

Biological traits and life table of the exotic Harmonia axyridis compared with Hippodamia variegata,and Adalia bipunctata (Col., Coccinellidae)

Abstract: As part of an environmental risk assessment study of exotic natural enemies used in inundative biological control, life‐history characteristics of Harmonia axyridis (Pallas), Hippodamia variegata (Goeze) and Adalia bipunctata (L.) (Col., Coccinellidae) were quantified under laboratory conditions at 25°C on Myzus persicae (Sulzer) as prey. Comparative studies showed significant differences among pre‐adult development times: H. axyridis developed slower ( = 19.8 days) than H. variegata ( = 18.1 days) and A. bipunctata ( = 18.4 days). Differences were also evident in the duration of egg, larval and pupal stages. No measurable differences among the three species were found for fecundity, oviposition rate and adult longevity. Harmonia axyridis exhibited the longest pre‐oviposition ( = 7.4 days) and interoviposition ( = 3.6 days) periods and the shortest oviposition period ( = 13.7 days). The Bieri model was used to describe age‐specific fecundity for the three species of coccinellids. The intrinsic rate of increase (r_m), net reproductive rate (R₀) and mean generation time (T) were higher for H. variegata (r_m = 0.114, R₀ = 52.75, T = 41.88 days) than for H. axyridis (r_m = 0.089, R₀ = 26.27, T = 38.81 days) or A. bipunctata (r_m = 0.081, R₀ = 18.49, T = 40.06 days). Our findings show that the biological traits of H. axyridis do not seem to be factors that may contribute to the invasiveness of this coccinellid.     

Effects of Aphid Prey on Larval Development and Mortality of Adalia bipunctata and Coccinella septempunctata (Coleoptera: Coccinellidae)

Developmental time and mortality rate of Adalia bipunctata (L.) and Coccinella septempunctata L. (Coleoptera: Coccinellidae) were determined when feeding on five aphid species. Metopolophium dirhodum (Walker), Sitobion avenae (F.), Rhopalosiphum padi (L.), Hyalopterus pruni (Geoffr.) and Myzus cerasi F. (Homoptera: Aphididae) are widespread in Tekirda?, Turkey. Tests were carried out in a controlled environmental chamber (25±1°C temperature, 65±5% relative humidity and 16 h light:8 h dark period). Developmental times for A. bipunctata and C. septempunctata larvae varied significantly depending on species of aphid prey (P<0.05). Development time (±S.E.) varied from 17.50±0.84 to 20.83±1.60 days for C. septempunctata and 16.7±0.76 to 20.7±1.03 days for A. bipunctata. Mortality of A. bipunctata (50%) and C. septempunctata (63%) were highest on H. pruni.     

Effects of competition,cannibalism and intra‐guild predation on larval development of the European coccinellid Adalia bipunctata and the invasive species Harmonia axyridis

Abstract 1. Resource competition and intra‐guild predation (IGP) are important determinants of the structure of aphidophagous guilds. The likelihood and outcome of IGP is influenced by the density of extra‐guild prey and the characteristics of the species involved. 2. The nature of intra‐guild interactions between alien and indigenous coccinellids often determines the success of coccinellid invasions, as exemplified by Adalia bipunctata in Japan and Harmonia axyridis in North America and Europe. 3. Harmonia axyridis has negatively impinged on indigenous species in its introduced range, and its recent arrival in Britain poses a threat for members of native aphidophagous guilds. IGP and inter‐specific competition between H. axyridis and British coccinellids are predicted to occur. However, the results of such interactions have been little studied. 4. Here we investigate the effects of different diets, designed to mimic possible conditions in the wild, on the survival, development, and adult size of H. axyridis and A. bipunctata. Results demonstrate a skew in the consequences of IGP between the two species: the supplementation of a limited aphid diet with non‐conspecific eggs leads to a significant advantage for H. axyridis in respect of all parameters assessed, but gives no benefit to A. bipunctata. 5. We conclude that IGP of A. bipunctata by H. axyridis will contribute to the spread and increase of H. axyridis in Britain. 6. We further conclude that the skewed nature of IGP between A. bipunctata and H. axyridis at least in part explains the limited spread of A. bipunctata in Japan.     

Interactions between the fungal pathogen Beauveria bassiana and three species of coccinellid: Harmonia axyridis, Coccinella septempunctata and Adalia bipunctata

Harmonia axyridis is a predatory coccinellid, native to central and eastern Asia. It has been available in many countries for use as a biological control agent of pest aphids and scale insects. In many of these countries, including the USA, H. axyridis has established. It is now considered an invasive alien species for a number of reasons, including its impact on functional biodiversity. Beauveria bassiana is known to be a natural mortality agent of overwintering coccinellids and is a potential candidate for the biological control of H. axyridis. In this paper we compare the susceptibility of three species of coccinellid, H. axyridis (cultures derived from Japan and UK), Coccinella septempunctata and Adalia bipunctata to infection by B. bassiana (commercial strain GHA) after exposure at three doses (10⁵, 10⁷, 10⁹ conidia ml⁻¹). The two subpopulations of H. axyridis (Japan and UK) were more resistant to B. bassiana infection than either A. bipunctata or C. septempunctata. This is exemplified by the median lethal doses at 10 days post-inoculation (LD₅₀) of 10^6.2, 10^6.0, 10^8.3, 10^9.6 conidia ml⁻¹ for A. bipunctata, C. septempunctata, H. axyridis (Japan) and H. axyridis (UK), respectively. Only doses of 10⁹ conidia ml⁻¹ resulted in mortality of H. axyridis, in contrast, 80% of C. septempunctata and 70% of A. bipunctata exposed to 10⁷ conidia ml⁻¹ of B. bassiana succumbed to infection. The fecundity (cumulative mean egg production over 10 days) of A. bipunctata and H. axyridis (UK) was also assessed. The fecundity of C. septempunctata could not be assessed because this species requires diapause prior to the onset of reproduction and these studies were on beetles that had recently eclosed (2–8 weeks). Harmonia axyridis (Japan) produced no eggs in most treatments including the control and so was excluded from analysis. High dose (10⁹ conidia ml⁻¹) inoculation reduced the fecundity of A. bipunctata to zero but egg production was similar for individuals inoculated with doses of 10⁵, 10⁷ conidia ml⁻¹ and control individuals. In contrast, all doses of B. basssiana reduced H. axyridis (UK) egg production dramatically. We discuss these results in relation to the potential for control of H. axyridis using B. bassiana.     

Genetic variation in larval period and pupal mass in an aphidophagous ladybird beetle (Harmonia axyridis) reared in different environments

Abstract Genetic trade‐offs for host plant use are hypothesized to facilitate the diversification of insect populations through specialization to their host plants. Previous studies mainly estimated the architecture of genetic variances and covariances in herbivorous species with discrete and limited types of host species. In contrast to herbivores, the relative abundance of resources for predatory species fluctuates in time and space, causing a more unpredictable encounter with prey species. The ecological characteristics of resource use might result in a differential mode of selection for herbivorous and predatory species, which could be reflected in a differential genetic architecture of developmental traits such as the duration of larval stage (henceforth referred to as larval period) and size of pupa (measured as pupal weight). This paper presents results from a study on the genetic architecture of larval period and pupal mass of an aphidophagous ladybird beetle, Harmonia axyridis Pallas, in different resource environments. Beetles reared on Acyrthosiphon pisum (Harris) showed a shorter developmental period and a heavier pupal mass than their siblings on Aphis craccivora Koch or on artificial diet, while the average larval period and pupal mass on A. craccivora and the artificial diet were similar. Further analyses of the genetic architecture suggest that the developmental traits on the two aphid species are genetically correlated, while there are only weak or no genetic correlations between these two traits on the two aphid preys and the artificial diet. Thus, the results suggest that the patterns of genotypic relationships between developmental traits differ from the phenotypic ones. The effects of past selection on the genetic architecture and the possible cause of the genetic correlation are discussed, as well as consequences for mass rearing for biological control.     

Role of surface chemicals in egg cannibalism and intraguild predation by neonates of two aphidophagous ladybirds, Propylea dissecta and Coccinella transversalis

Abstract:  The role of surface chemicals in egg cannibalism and intraguild predation by neonates of two aphidophagous ladybirds, Propylea dissecta and Coccinella transversalis were examined. Neonates of both species prefer to eat non-sibling conspecific eggs than heterospecific eggs, with higher preference in P. dissecta . Surface chemicals appear to play a major role for the preference of conspecific eggs, as the ladybird behaviour was reversed when these chemicals were interchanged. The surface chemicals present on the eggs possibly act as feeding stimulants to conspecific neonates but not for heterospecific neonates. Egg clustering enhances the effect of surface chemical and stimulate non-sibling egg cannibalism and appears to reduce intraguild predation. Egg clustering is advantageous to ladybirds, as it can stimulate non-sibling cannibalism by neonates. It appears that aggregation of chemicals present on the conspecific egg surface possibly attracts the hungry conspecific neonate, providing the first meal for its survival, while protecting against heterospecific predators. Neonates of both ladybirds were reluctant to eat heterospecific eggs.     

Population field studies of the aphidophagous ladybird beetleHarmonia axyridis (Coleoptera: Coccinellidae): Life tables and key factor analysis

1. Life tables of the predatory ladybird beetle Harmonia axyridis were analysed by taking samples from twenty or twenty four sites colonized by eight species of aphids for two years.
2. Larval mortality was a key factor in the H. axyridis populations. Mortality of all the stages tended to be density-dependent when life cycles were divided into four developmental stages, except in the case of mortality at hatching due to sibling cannibalism.
3. Sibling and non-sibling cannibalism played an important role on population stability and persistence.

     

Effects of mixed prey on the development and demographic attributes of a generalist predator,Coccinella septempunctata (Coleoptera: Coccinellidae)

Coccinella septempunctata Linnaeus, 1758 (Coleoptera: Coccinellidae) is an aphidophagous ladybird beetle species with cosmopolitan distribution. However, it may also thrive on arthropods other than aphids, when the latter are not readily available. Certain life history traits and demographic attributes of C. septempunctata were determined using seven different diets with different alternations and proportions of an aphid, Lipaphis erysimi (Kaltenbach,1843) and a mite, Tetranychus urticae Koch, 1836, in the laboratory (at 25±0.5°C, 65±5% RH and a photoperiod of 16 h L:8 h D).The larval duration was longest (12.61±6.17 days) when fed an alternating diet of two days aphid/two days mite. Adult longevity was longest (78.65±1.09 days) when fed aphids only and shortest (3.17±1.25 days) when fed mites only. Life expectancy (e_x) was highest (111 days) when adults were fed only aphids and lowest (11.3 days) when fed only mites. Survival rates of ladybird beetles were positively related to an increasing ratio of aphids in their diet. Their ability to prey on both aphids and mites indicates the effectiveness of C. septempunctata as a biological control agent on plants infested with these two pests.     

The use of honeydew in foraging for aphids by larvae of the ladybird beetle, Coccinella septempunctata L. (Coleoptera: Coccinellidae)

Abstract.  1. To clarify the use of honeydew in foraging for aphids by larvae of the ladybird beetle, Coccinella septempunctata L., searching behaviour of ladybird larvae for Aphis craccivora Koch and Acyrthosiphon pisum Harris and the abundance of honeydew under aphid colonies were examined in laboratory experiments.
2. More larvae responded by climbing the plants with aphids than responded to plants without aphids. When the plants were replaced with sticks, in order to exclude visual and olfactory cues from plants and aphids, more larvae of C. septempunctata climbed sticks above the area that contained honeydew than climbed sticks above the area that did not contain honeydew. Then, ladybird larvae use honeydew as a contact kairomone when foraging for aphids.
3.  Aphis craccivora deposited a larger number of honeydew droplets beneath the plants than did similar numbers of A. pisum. Thus, C. septempunctata larvae licked more frequently the honeydew of A. craccivora than that of A. pisum and spent longer searching on the area containing honeydew of A. craccivora than that of A. pisum . Consequently, a larger number of larvae climbed a stick above honeydew of A. craccivora than that of A. pisum.
4. It may be also considered that C. septempunctata larvae can distinguish honeydew of the two aphid species and respond more strongly to A. craccivora than A. pisum.