REPRODUCTIVE BEHAVIOUR OF TWO APHIDOPHAGOUS LADYBEETLES, CHEILOMENES SEXMACULATA AND COCCINELLA TRANSVERSALIS

Abstract  Reproductive behaviour of two aphidophagous ladybeetles, Cheilomenes sexmaculata and Coccinella transversalis was studied. A premating period of 5.0±0.5 and 11.7±0.4 days and a pre-oviposition period of 5.5±0.7 and 12.7±0.5 days was observed for C. sexmaculata and C. transversalis , respectively. Males of both the species exhibited courtship in five steps, viz . approach, watch, examine, mount and attempt. Sexually immature, recently mated and ovipositing females rejected male advances in both the species. Chemical, visual and behavioural cues probably play a role in mate recognition. Quiescent mating occurred in C. sexmaculata , whereas abdominal shakings in the form of bouts and strokes were characteristic in C. transversalis. C. sexmaculata had a relatively prolonged mating duration (133.4±z8.9 min) than C. transversalis (37.9±2.0 min), possibly due to the absence of active processes, i.e ., bouts and strokes. The active processes in C. transversalis decreased with multiple matings in a day. Unmated adults of both the species mated more vigorously than the mated ones. Reproductive performance of both the species was best after multiple matings.     

Aggregation of polyphagous predators in response to multiple prey: ladybirds (Coleoptera: Coccinellidae) foraging in alfalfa

The spatial distribution of polyphagous predators may often reflect the integration of aggregative responses to local densities of multiple species of prey, and as such may have consequences for the indirect linkages among the prey sharing these predators. In a factorial field experiment in which we manipulated local prey densities within a field of alfalfa in Utah (USA), we tested whether aphidophagous ladybirds would aggregate not only in response to their primary aphid prey, but also in response to an abundant alternative prey, the alfalfa weevil (Hypera postica [Gyllenhal]). Native North American ladybirds (primarily Hippodamia convergens Guerin and H. quinquesignata quinquesignata [Kirby]) responded only to spatial variation in aphid density. In contrast, the introduced ladybird, Coccinella septempunctata L., aggregated also at local concentrations of the weevil late in the experiment when weevil density was high and aphid density was relatively low throughout all experimental plots. The results support the hypothesis that C. septempunctata is more responsive than are native ladybirds to the availability of alternative prey in alfalfa, which may account in part for the displacement of native ladybirds from alfalfa by the introduced species as aphid numbers have declined. The differing responses of the native and introduced ladybirds to spatial patterns of the alternative prey underscore the importance of extending the study of predator aggregation to understand better how polyphagous predators distribute themselves in response to spatial patterns of multiple species of potential prey.     

改变人工饲料组分对七星瓢虫幼虫生长发育的影响

改变人工饲料的含氮物质和脂类以及温度对七星瓢虫幼虫生长发育有明显影响.幼虫取食含有脂类物质的饲料时,化蛹率可达90%左右,生长 历期明显缩短,成活率增加;食物中缺乏某些脂肪酸对幼虫生长发育不利,其中亚麻酸和油酸是必需的因素.据测定人工饲料中的游离氨基酸含量低于蚜虫中的水平,而蛋白质水解氨基酸的含量则较蚜虫中高.饲料中加入酵母水解物使幼虫生长加快,体重显著增加.幼虫在28℃时成活率和化蛹率均较在其他温度高,此时幼虫的取食和食物利用加强.幼虫取食改进的饲料时除体重外,在生长期、成活率、化蛹率都接近取食蚜虫时的水平.     

七星瓢虫精母细胞内轴丝的形态发生(英文)

应用细胞整装技术研究了七星瓢虫精子轴丝的早期形态发生和超微结构。在精子发生期间,起源于中心粒的两对基体—轴丝复合体出现在精母细胞内,在分裂间期它们彼此完全分离。当基体—轴丝复合体附着于精细胞核的核膜上,中心粒附体开始发生于生长轴丝的近心端,在染色质凝聚前中心粒附体最大。生长着的轴丝伴随着凝聚细胞核伸长。一个早期基体—轴丝复合体的轴丝是由具有内、外动力蛋白臂的9个双微管组成,缺少中央微管。     

瓢虫对杀虫剂的敏感性研究

用4种不同类别杀虫剂对3种不同用药水平地区的七星瓢虫Coccinella septempunctataLinnaeus、龟纹瓢虫Propylea japonica (Thunberg)的毒力进行了测定,同一种用药水平地区的瓢虫对不同药剂的敏感性差异均极显著,三氟氯氰菊酯>灭多威>甲胺磷>硫丹;三氟氯氰菊酯对用药水平较高地区的七星瓢虫幼虫、成虫的毒力分别为硫丹的8547和617倍。同种药剂对不同用药水平地区的七星瓢虫的毒力差异不显著,而用药水平较高地区的龟纹瓢虫较用药水平较低地区的龟纹瓢虫对三氟氯氰菊酯产生了30.6倍的抗药性,这与羧酸酯酶活性提高有关。不同种类杀虫剂对七星瓢虫和抗性棉蚜Aphis gossypii Glover的选择指数差异极为显著,硫丹>灭多威>甲胺磷>三氟氯氰菊酯,如硫丹为4.9,而三氟氯氰菊酯却仅为7.3X10^-6。硫丹是防治抗性棉蚜值得重视的一种杀虫剂。     

Crowding inhibits pupation inTribolium freemani: contact chemical and mechanical stimuli are involved

The relationship between the development ofCoccinella septempunctata brucki Mulsant (Coleoptera: Coccinellidae) and its parasitoid,Perilitus coccinellae (Schrank) (Hymenoptera: Braconidae) was studied at two photoperiods (L 16:D8 and L 12: D12) at 26°C. The development ofP. coccinellae is well synchronized with the physiological state of the host,C. septempunctata, which can be parasitized not only as adult but also as larva or pupa. The parasitoid larva completed larval development within 19 days in a non-diapausing host, while in diapausing adults as well as in pupae held at diapause-averting conditions, the parasitoid larva ceased growth at the first instar. Growth was resumed when diapause of the host terminated or by the emergence of the adult host from the pupa. About 550 spheric cells, teratocytes, were liberated into the host hemocoel when the parasitoid egg hatched. The teratocytes increased in size in the active host, while their development was arrested in the diapausing host. Application of methoprene caused diapause termination of both host and parasitoid larva. The results indicate that the development of the larva ofP. coccinellae depends on the physiological conditions of the host,C. septempunctata brucki. The host-parasite relation thus represents an ‘endogenous synchronization’ in the sense of Schoonhoven's definition.     

七星瓢虫唇须感器分布和统计特征的雌雄差异

应用扫描电镜观察七星瓢虫Coccinella septempunctata的唇须和附节,以便确认在感应农药残留时起主要作用的化学感受器。研究证明分布在下颚须上的感器类型包括两种锥形感器（兼有机械感受器和化学感受器的功能）和一种钟形感器。同时本文首次报道了对这些感器精确的形态测量,明确了其性二型性。对下颚须的测量表明其左右末节的长度差异与七星瓢虫的性别之间有明显的相关性。文中还记述了下唇须上一种新的钟形感器,其在每个下唇须上的数量大约为12～17个。经测量这些机械感受器的平均直径为2.4 μm。早期研究中所记述的锥形感器被证实是下唇须上仅有的化学感应器,并且首次证明这些锥形感器的数量与性别相关,雄性平均为18个,雌性平均为16个。附节上也存在性别差异： 第2跗节跗垫的宽度在雄性中是从后向前逐渐增大,而在雌性中刚好相反。本文还就这些差异的意义以及新发现感器的功能进行了讨论。     

冀中农区大草蛉(Chrysopa septempunctata)栖息地选择

大草蛉(Chrysopa septempunctata)是华北农区的主要天敌昆虫,研究了作物主要生长季节大草蛉的分布动态及其对栖息地的选择取向,结果表明,(1)大草蛉对栖息生境有较强的选择性,明显趋向于田间杂草地生境;(2)大草蛉在田间草地带上的栖息较为稳定,且受田间草地带宽度的直接影响,宽度1m左右的草地带有更高的大草蛉密度;(3)林带对大草蛉分布显示出积极作用,其效应范围因林带结构不同表现各异;(4)作物生长后期林带逐渐成为大草蛉栖息的重要场所。     

Intraguild interactions between the entomopathogenic fungus Pandora neoaphidis and an aphid predator and parasitoid at the population scale

The interactions that occur between the entomopathogenic fungus Pandora neoaphidis and a predator (Coccinella septempunctata) and a parasitoid (Aphidius ervi) were assessed in microcosm and polytunnel experiments. Transmission of P. neoaphidis to the pea aphid, Acyrthosiphon pisum, was enhanced in the presence of both C. septempunctata and A. ervi in microcosm experiments done under fixed abiotic conditions. In contrast, the reproductive success of A. ervi was reduced in the presence of P. neoaphidis. Despite the increased fungal transmission in the presence of C. septempunctata, there was no additional decrease in the aphid population indicating that P. neoaphidis is functionally redundant in the presence of the coccinellid. In polytunnel experiments the reproductive success of A. ervi was not affected by P. neoaphidis. These results do not support those of the microcosm and may be due to the more natural abiotic conditions in the polytunnel reducing the competitive advantage of the fungus. Microcosms therefore provide an arena in which the interactions between fungal pathogens and other aphid-natural enemies can be assessed however, further assessments at increased spatial scales under more natural abiotic conditions are also required to accurately determine the outcome of these interactions.     

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。