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.

     

Effect of cannibalism and predation on the larval performance of two ladybird beetles

The relative impact of cannibalism and predation on the development and survival of fourth instar larvae was assessed in two species of aphidophagous ladybird beetles, Coccinella septempunctata and Harmonia axyridis. The effect of eating aphids, conspecific larvae or heterospecific larvae on larval performance differed in the two species: aphids were the best food for C. septempunctata and survival of C. septempunctata larvae was significantly lower when offered heterospecific larvae rather than conspecific larvae or aphids as food, indicating that H. axyridis larvae were not suitable food for C. septempunctata. However, as the different foods did not affect the larval performance of H. axyridis, this species appears to be more polyphagous. Both intraguild predation by the aggressive larvae of H. axyridis and the polyphagous food habit of this species may account for its dominance in ladybird assemblages and its displacing other ladybird beetles in several places in the world.     

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.     

不同温度条件下异色瓢虫四龄幼虫亲缘关系对自残行为的影响

在14、18、22、24℃及30℃下对异色瓢虫Harmonia axyridis(Pallas)的不同同血缘的四龄幼虫自残行为及其对生长发育的影响进行研究。结果表明,异色瓢虫四龄幼虫自残发生概率受环境温度条件影响显著。在22-24℃处理范围内同血缘个体间自残发生概率均显著小于非同血缘个体。自残滞后时间同样受环境温度条件影响显著,且在同一温度条件下同血缘个体间均显著小于非同血缘处理。个体间相互攻击率不受环境温度变化影响,而在高于22℃下受血缘关系影响显著。此外,总受攻击次数在不同温度处理间差异显著。同血缘个体间自残后死亡率随温度增加而减少,均在30%以上。而非同血缘个体间自残后死亡率不受温度变化影响,均在70%以上。自残后残存个体的化蛹率及成虫羽化率均不受环境温度变化及个体间血缘关系的影响,化蛹率除30℃处理外均在90%以上,而在各温度下两血缘处理的羽化率均大于70%。     

Dropping behaviour of larvae of aphidophagous ladybirds and its effects on incidence of intraguild predation: interactions between the intraguild prey, Adalia bipunctata (L.) and Coccinella septempunctata (L.), and the intraguild predator, Harmonia axyridis Pallas

Abstract.  1. Two experiments were performed in the laboratory to assess the behaviour of dropping from a host plant as a defence against intraguild predation in aphidophagous ladybird larvae.
2. In the first experiment, encounters were observed on bean plants between fourth instars of the intraguild predator species, Harmonia axyridis , and first instars of two other ladybird species, Adalia bipunctata (L.) and Coccinella septempunctata (L.). The percentages of first instars of the latter two species that dropped from the plant in response to attack differed dramatically, with 47.5% of C. septempunctata first instars dropping vs. 0% of A. bipunctata .
3. In the second experiment, first instars of A. bipunctata or C. septempunctata and a fourth instar of H. axyridis were allowed to forage together on bean plants for 3 h. During this time, 44.3% of C. septempunctata larvae dropped from the plant, but less than 2% of A. bipunctata larvae did so. In contrast, 95.0% of A. bipunctata larvae fell victim to intraguild predation by H. axyridis vs. only 54.5% of C. septempunctata larvae.
4. The significance of dropping behaviour of ladybird larvae as a defence against intraguild predation, and the relationship of dropping behaviour to species-specific habitat affinity of ladybirds, is discussed.     

Cannibalizing Harmonia axyridis (Coleoptera: Coccinellidae) larvae use endogenous cues to avoid eating relatives

Cannibalism is widespread among many different organisms, and can have both negative and positive fitness consequences. Avoiding eating relatives can minimize negative fitness consequences of cannibalism. Such avoidance requires kin discrimination, but evidence for this ability among cannibals is limited with little data that address the cues used in such discrimination. We examined whether larvae of the ladybird beetle Harmonia axyridis avoid eating their relatives. We further manipulated environmental factors to create individuals that had similar or dissimilar rearing environments to begin to test for endogenous versus exogenous recognition cues. In our experiments, third-instar larvae were much less likely to cannibalize if they were interacting with a relative. Larvae that did cannibalize kin required more encounters, and significantly delayed cannibalism, compared to larvae cannibalizing unrelated individuals. Acquired cues were less important. Even though the different rearing environment resulted in significantly different phenotypic effects, similarity or dissimilarity of rearing environment had no effect on cannibalism, and there was no interaction between environments and relatedness in cannibalism. We suggest that H. axyridis has a well-developed kin discrimination system, and that kin recognition in this ladybird beetle is based on endogenous rather than exogenous cues. We also argue that these cues reflect either direct or indirect genetic effects on larval phenotypes.     

The potential impacts of the arrival of the harlequin ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), in Britain

Abstract.  1. The harlequin ladybird, Harmonia axyridis , has recently arrived in Britain.
2. This species has been introduced from Asia into many parts of the world for biological control purposes.
3. In many parts of North America it has become the predominant aphidophagous coccinellid in less than 20 years, and in north-western Europe it is spreading and increasing in number rapidly.
4. Since establishment in North America and continental Europe, reports of its effectiveness as a biological control agent of aphids and coccids have been accompanied by accounts of negative effects on other aphidophagous species and humans.
5. Here the potential impacts of the arrival of the harlequin ladybird in Britain are assessed.     

Fitness consequences of plants growing with siblings: reconciling kin selection, niche partitioning and competitive ability

Plant studies that have investigated the fitness consequences of growing with siblings have found conflicting evidence that can support different theoretical frameworks. Depending on whether siblings or strangers have higher fitness in competition, kin selection, niche partitioning and competitive ability have been invoked. Here, we bring together these processes in a conceptual synthesis and argue that they can be co-occurring. We propose that these processes can be reconciled and argue for a trait-based approach of measuring natural selection instead of the fitness-based approach to the study of sibling competition. This review will improve the understanding of how plants interact socially under competitive situations, and provide a framework for future studies.     

异色瓢虫与隐斑瓢虫的区别及其色斑型和横脊的频率

异色瓢虫Harmonia axyridis(Pallas)和隐斑瓢虫H.yedoensis(Takizawa)是亲缘关系很近的姐妹种,在中国(北京到南岭,西至甘肃南部和西藏东部)、日本(北海道以南)和南韩等地同域分布,常常在松树等植物上共存。长期以来,隐斑瓢虫被认为是异色瓢虫的一个异名。有时从外形上很难区分这2种瓢虫,因此对于依据野外数据,分析异色瓢虫色斑型和鞘翅横脊的发生频率及小进化会产生一些错误。本文从没有隐斑瓢虫分布的东北地区的材料及其他数据,报道异色瓢虫的色斑型及鞘翅横脊发生频率。异色瓢虫的花斑型在我国东部地区(从东北至广东北部,西至甘肃和云南)发生率很低,而在新疆西北部发生率较高。鞘翅横脊的发生率从东北佳木斯的98.85%降低到云南大理的78.26%。本文列出了区分这2种瓢虫的形态特征及自然分布。如果鞘翅具横脊,则属于异色瓢虫,但如果标本来自2种瓢虫的共存区,鞘翅没有横脊,鞘翅的斑纹呈花斑型、四窗型或二窗型,则很难从外部形态上对它们进行鉴定。但这2种瓢虫的幼虫很容易区分。本文还提供了2种瓢虫的雄性外生殖器形态图、幼虫和成虫。     

异色瓢虫幼虫对卵的种内自残和种间捕食

自残现象的发生在异色瓢虫Harmonia axyridis中很是常见,为明确自残行为对其存活和生长发育的影响,在非选择性条件下我们对异色瓢虫幼虫对非姊妹卵的种内自残和对七星瓢虫Coccinella septempunctata卵的种间捕食进行了研究。结果表明,异色瓢虫取食同种卵和异种卵均可完成生长发育,与取食蚜虫相比：①其从卵到成虫及蛹期的发育历期明显缩短（P<0.05）,其中1龄幼虫发育历期缩短非常明显（P<0.01）;②自然条件下高死亡率的1龄幼虫的存活率明显提高（P<0.05）;③2-4龄幼虫、蛹和成虫的体重变轻（P<0.05）,且体长在4龄幼虫间也表现出显著差异（P<0.05）。这表明异色瓢虫种内自残和种间捕食对其在食物恶劣条件下延续种群至关重要,但对种群的繁衍却不是最理想的途径。     

Experimental evidence for the phenotypic impact of admixture between wild and biocontrol Asian ladybird (Harmonia axyridis) involved in the European invasion

Hybridization can fuel evolutionary processes during biological invasions. The harlequin ladybird Harmonia axyridis has long been used as a biocontrol agent before the species became invasive worldwide. Previous analysis based on microsatellite data has shown that European invasive populations bear traces of admixture between an eastern North American source, which is at the origin of the worldwide invasion, and biocontrol strains used in Europe. In this study, we tested the hypothesis that this early admixture event may have fostered the European invasion by impacting on the phenotypes of wild European populations. Mean life history traits of experimental F(1) hybrids are compared with pure parental sources and wild European crosses. Our results reveal a biased impact whereby North American beetles benefitted from being admixed with European biocontrol strains. Resemblance between experimental hybrids and wild European invasive crosses further suggests a long-lasting effect of admixture that may still be at work and fostering invasiveness.     

Antennal sensory organs and glands of the harlequin ladybird,Harmonia axyridis

Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is a sub‐cosmopolitan species. Native to Asia, it has been released during the 20th century for classical and augmentative biological control of several herbivorous insects, mostly aphids and coccids. Despite its recognized positive impact on biological control, H. axyridis is now considered among the most dangerous invasive species in Europe and in most places where it has established. This is mostly due to its ability to reduce the populations of native predatory species of the same trophic guild. When exploring a new area, H. axyridis adults use semiochemical cues to acquire information about the habitat. Presumably, these cues are perceived by the sensilla located on the antennae. Surprisingly, in spite of the huge literature existing on H. axyridis, the antennal sensory organs have been poorly characterized. Here, we used scanning and transmission electron microscopy (SEM, TEM) techniques to study H. axyridis antennae, with focus on the various types of sensilla and their distribution in male and female individuals. The presence of various classes of antennal sensilla belonging to the main types described in insects (chemoreceptors, mechanoreceptors, and thermo‐hygroreceptors) was highlighted, as well as the widespread presence of antennal glands. The investigations showed some peculiar characteristics not known in Coccinellidae, such as the concentration of sensory structures at the level of the distal part of the apical antennomere and the discovery of antennal glands associated with it. No sexual dimorphism was revealed, neither for the general structure of the antenna (similar number of antennomeres and presence of modifications), nor for the total length and width of the antenna, the relative size of the antennomeres, the types of antennal sensilla, of their distribution and abundance. The potential relevance of these sensory structures and antennal glands, reported for the first time in Coccinellidae, is discussed in the context of intra‐ and interspecific communication.     

Relationships Between Attack and Escape Rates, Cannibalism, and Intraguild Predation in Larvae of Two Predatory Ladybirds

We compared incidences of cannibalism and intraguild (IG) predation (IGP) and quantified attack and escape rates—mechanisms which possibly account for the difference in incidences of these interactions—in laboratory experiments with Harmonia axyridis and Coccinella septempunctata. There was a tendency for H. axyridis to act as an IG predator and C. septempunctata as an IG prey. Cannibalism was also often observed in both species. The incidences of both IGP and cannibalism were different between the species. The average attack rates of C. septempunctata were less than 20%, but those of the more aggressive H. axyridis exceeded 50%. Larvae of both species attacked conspecifics and heterospecifics H. axyridis larvae successfully escaped when attacked by both conspecifics and by heterospecifics, while larvae of C. septempunctata escaped from attacks of conspecifics but not from those of heterospecifics. Thus the aggressive behavior of H. axyridis, in particular, of the third and fourth instars, negatively affects the larval survival of C. septempunctata. It may contribute to the dominance of H. axyridis in ladybird assemblages and its displacement of other ladybird species in several places in the world.     

6种常用杀菌剂对苹果黄蚜及其天敌异色瓢虫的影响

本文研究了有机苹果园常用的6种杀菌剂,包括农抗120、绿乳铜、高锰酸钾、大生M-45、成标和多菌灵对果园重要害虫苹果黄蚜和h／scitricolavander Goot及其天敌异色瓢虫Harmoniaaxyridis Pallas死亡率的影响。结果表明,这6种杀菌剂使用喷雾和浸叶饲喂法对蚜虫的死亡率均有一定的影响,但校正死亡率均小于21％。喷雾处理和二次中毒处理对瓢虫幼虫的死亡率均无显著影响。上述结果说明6种供试杀菌剂的常用浓度对蚜虫有较低的致死率,而对其天敌异色瓢虫则是安全的,因此我们推测上述杀菌剂的常规使用不会对果园昆虫的群落结构造成重大影响。     

Ecology and biological control application of multicoloured Asian ladybird, Harmonia axyridis: A review

The ecology of and biological control by multicoloured Asian ladybird beetle, Harmonia axyridis (Pallas) are reviewed. Our emphasis is on assembling and interpreting information on general characteristics, invasion and establishment, sexual activity, foraging and predation, development, survival and reproduction, predator-predator interactions, natural enemies, biocontrol, non-target effects and status of H. axyridis as a pest of fruits. Colonization of H. axyridis for aphid biocontrol in the USA have been successful in terms of its establishment, but its abundance is turning out to be a nuisance to humans. Its harmful non-target impact on beneficial organisms, humans and native species is becoming a debatable issue. The question on its present position, whether it is a biocontrol agent or pest, is a critical issue and discussed. Inferences from the empirical data are made and new avenues for future research are suggested.     

三种捕食性瓢虫成虫对卵的种内自残及其集团内捕食作用

捕食性瓢虫是农田生态系中一类重要的天敌昆虫,种内自残和集团内捕食现象在捕食性瓢虫中普遍存在。本研究在室内通过选择性和非选择性试验比较分析了异色瓢虫、七星瓢虫及龟纹瓢虫成虫对卵的种内自残和集团内捕食作用以及卵表面的化学物质对集团内捕食作用的影响。结果表明:在非选择性试验中,3种捕食性瓢虫成虫对卵表现出相似的取食现象,即对龟纹瓢虫卵取食最多,其次为七星瓢虫卵,对异色瓢虫卵取食相对较少;在选择性试验中,七星瓢虫和龟纹瓢虫较偏好取食同种卵,对异色瓢虫卵取食均较少;而异色瓢虫喜欢取食异种卵,对同种卵取食相对较少。3种瓢虫卵经正己烷漂洗后,异色瓢虫、七星瓢虫和龟纹瓢虫成虫却未对卵表现出取食偏好性。本研究可为捕食性瓢虫组合释放与协调利用、田间集团内捕食作用评定及其在生物防治中的应用提供理论依据。     

Sibling cannibalism in aphidophagous ladybirds: its impact on sex-dependent development and body weight

Abstract:  The effects of sibling egg cannibalism on sex-dependent development and adult body weight were determined by rearing simultaneously two groups of sibling larvae of ladybirds, viz. Propylea dissecta and Coccinella transversalis individually. The first group included cannibals (i.e. neonates, which took a sibling egg as the first meal and later fed on aphids, Aphis craccivora ) and the other included non-cannibals (reared exclusively on aphids). The cannibal larvae developed faster with heavier adults than non-cannibals. This expedited development and nutritional advantage (increased body weight) was greater in first instars indicating maximum benefit of sibling cannibalism to them. Sibling cannibalism was relatively more advantageous to male than to female ladybirds. Laboratory data predict that the larger size of adults in the field could possibly be the result of sibling egg cannibalism at the neonate level.     

Mechanisms of prey finding in the aphidophagous ladybird beetle,Harmonia axyridis [Coleoptera: Coccinellidae]

The mechanism of prey finding in adultHarmonia axyridis was investigated by presenting beetles with small gauze or polyethylene bags containing either aphidinfested leaves or healthy leaves alone together with empty control bags. Beetles were attracted to bags by olfactory and visual cues suggesting the presence of aphids, including the odor of aphid-infested leaves, the odor of aphids, the odor of healthy leaves, and the sight of leaves. Particularly effective in prolonging beetles's stay on bags visited was the odor of aphid-infested leaves. It is suggested that adults ofH. axyridis use olfactory and visual cues to detect prey before actual contact occurs. Use of such cues seems more advantageous than random searching, as has been reported in many previous studies of coccinellid foraging.

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Résumé Le mécanisme de découverte de la proie chez l'adulte d'Harmonia axyridis est étudié en donnant aux Coccinelles de petits sacs en gaze ou en polyéthylène contenant soit des feuilles infestées de pucerons, soit des feuilles saines seules, avec des sacs vides comme témoins. Les coccinelles sont attirées vers les sacs par des indicateurs olfactifs ou visuels suggérant la présence de pucerons, incluant l'odeur des feuilles infestées de pucerons, l'odeur des pucerons, l'odeur des feuilles saines et la vue des feuilles. L'odeur des feuilles infestées de pucerons est particulièrement efficace en prolongeant le séjour des Coccinelles sur le sac visité. Il est suggéré que les adultes d'H. axyridis utilisent des indicateurs olfactifs et visuels pour détecter leur proie avant que s'établisse le véritable contact. L'emploi de tels indicateurs semble plus avantageux que la recherche au hasard, comme cela a été indiqué dans de nombreuses études antérieures sur la quête alimentaire des Coccinelles.