Reproductive performance of four aphidophagous ladybirds on cowpea aphid, Aphis craccivora Koch

Abstract:  This study investigated prey consumption, egg production, percent progeny loss, reproductive, pre- and post-reproductive periods, reproductive time ratio, reproductive rate and bioconversion efficiency of four aphidophagous ladybirds, viz. Cheilomenes sexmaculata (Fabricius), Coccinella septempunctata Linnaeus, Coccinella transversalis Fabricius and Propylea dissecta (Mulsant) on Dolichos lablab Linnaeus infested with cowpea aphid, Aphis craccivora Koch. C. sexmaculata had the highest bioconversion efficiency, reproductive rate and reproductive time ratio followed in rank order by P. dissecta , C. transversalis and C. septempunctata . This study indicates that C. sexmaculata has a narrow ecological relationship with A. craccivora . The increased allocation of resources to reproduction as indicated through a high reproductive time ratio and high bioconversion efficiency of C. sexmaculata and P. dissecta suggest that they may be better adapted to compete for this prey with larger species like C. transversalis and C. septempunctata .     

Growth and development of immature life stages ofPropylaea 14-punctata L. andCoccinella 7-punctata L. [Col.: Coccinellidae] simulated by the metabolic pool model

The conversion of aphid prey tissue (Acyrthosiphon pisum Harris) into predator biomass (immature life stages ofPropylaea 14-punctata L. andCoccinella 7-punctata L.) is calculated by plotting weight gain against assimilation (i.e. consumption minus egestion). This concept is added to the metabolic pool model byGutierrez et al. (1981) that enables the simulation of growth and development of a predator on a physiological basis. Physiological time is expressed in daydegrees above lower development thresholds for both species. Visual examination of observed and calculated values showed that the model satisfactorily describes the growth patterns of the above predators.      

Sub-lethal effects of deltamethrin residues on the within-crop behaviour and distribution ofCoccinella septempunctata

The behaviour and distribution of adultCoccinella septempunctata L. (Coleoptera: Coccinellidae) were recorded in two plots of winter wheat infested with the cereal aphidsSitobion avenae (F.) andMetopolophium dirhodum (Walk.) (Homoptera: Aphididae). One plot was sprayed with the pyrethroid insecticide deltamethrin at a rate of 6.25 g a.i./ha and the other was left unsprayed. Single ladybird beetles were released sequentially on the ground at the centre of the sprayed and unsprayed plots and their behaviour and position in the crop canopy were recorded at 30 second intervals for a total of 15 min per beetle. Assessments, with fresh beetles, continued for four days after spray application with a total of eighty ladybird beetles observed. The 15 min period was selected to avoid lethal effects and no ladybird beetles were killed or knocked down as a result of exposure to deltamethrin residues during this period. Significant differences were found between the overall behaviour patterns ofC. septempunctata in the untreated and deltamethrin treated plots up to three days after the spray application. Ladybird beetles exposed to deltamethrin residues were observed to walk and groom significantly more frequently and to rest significantly less frequently than those in the unsprayed plot. Significant differences were also found between the observed distribution of ladybird beetles in the sprayed and unsprayed crop canopies, with higher numbers of observations towards the bottom of the crop canopy and on the ground in the deltamethrin treated plot than in the untreated plot during the first two days after deltamethrin application. Upon the foliage itself, ladybird beetles were observed significantly more frequently on the abaxial leaf surface in the deltamethrin treated crop compared with the untreated crop. The results are discussed in terms of possible evidence for the repellency of deltamethrin toC. septempunctata and also the implications for integrated pest management of changes in predator behaviour and crop distribution resulting from sub-lethal uptake of insecticides.     

MORPHOGENESIS OF THE AXONEME IN THE SPERMATOCYTE OF COCCINELLA SEPTEMPUNCTATA LINNAEUS

Abstract  Using cell whole mount preparation, early morphogenesis and ultrastructure of the axoneme of Coccinella septempunctata L. spermatocyte were investigated by transmission electron microscope. During spermatogenesis two pairs of basal body-axoneme complexes originated from centrioles are found in the spermatocyte and they are separated completely from each other at interkinesis. The centriolar adjunct begins to generate while a basal body-axoneme complex is attached to the nuclear envelope of a spermatid nucleus, and it, on the proximal end of a growing axoneme, reaches a maximum before chromatin condensation. The growing axoneme is accompanied by the condensable nucleus elongation. The early axoneme of a basal body-axoneme complex consists nine doublets with only inner and outer dynein arms, no central microtubules.     

七星瓢虫的卵黄发生:体外培养的脂肪体中卵黄原蛋白的合成

为了深入研究七星瓢虫的卵黄发生及其激素调节机理,我们建立了脂肪体的体外培养方法,证明了脂肪体在体外培养条件下能够正常进行卵黄原蛋白的合成与分泌。在体外合成的卵黄原蛋白与体内合成的具有相同的电泳迁移率、免疫学特性和部分水解肽谱。放射性氨基酸在体外参人卵黄原蛋白的动力学与在体内的相似。用脂肪体的体外培养方法,结合放射免疫沉淀、SAS-聚丙烯酰胺凝胶电泳、放射自显影等技术,研究了不同发育期脂肪体的合成能力,以及取食人工饲料的雌虫中保幼激素类似物对卵黄原蛋白合成的促进作用。     

6种复配杀虫剂对七星瓢虫的毒力测定及风险评估

采用药膜法分别测定了10％甲维盐·茚虫威悬浮剂、12％甲维盐·虫螨腈悬浮剂、12％虫螨腈·虱螨脲悬浮剂、14％呋虫胺·螺虫乙酯悬浮剂、22％吡虫啉·螺虫乙酯悬浮剂和6％吡虫啉·高效氯氟氰菊酯悬浮剂6种复配杀虫剂对七星瓢虫Coccinella septempunctata Linnaeus幼虫急性毒性,并进行了初级风险评估.结果 显示,6种药剂对七星瓢虫48 h的LR5o(半致死用量,Median lethal rate)分别为0.812、2.255、4.082、22.735、6.755和0.00467 g a.i/hm2.在农田内暴露场景下,6种复配杀虫剂对七星瓢虫风险均不可接受;在农田外暴露场景下,仅有14％呋虫胺·螺虫乙酯悬浮剂和22％吡虫啉·螺虫乙酯悬浮剂对七星瓢虫风险可接受,其它均不可接受.结果 表明在田间最大推荐用量下,6种药剂对七星瓢虫的初级风险评价均存在高风险.     

七星瓢虫基础研究现状

七星瓢虫对蚜虫等农林业中的重要害虫有较强的控制作用,利用七星瓢虫进行控害的生物防治技术正在逐步推广。本文就七星瓢虫的生物学特性、捕食、对农药的反应以及人工饲养等方面进行综述:七星瓢虫幼虫随龄期增长逐渐出现黄斑,温湿度对生长发育影响较大,以成虫越冬,有滞育现象。七星瓢虫捕食性强,捕食对象较多,包括多种蚜虫、木虱、蚧虫、粉虱、蓟马、网蝽等,其捕食功能反应模型主要为HollingⅡ型,捕食效应受温度、光周期及其猎物密度与自身密度影响。七星瓢虫对农药有一定的选择性,农药对七星瓢虫捕食行为及其生长发育有一定的影响,并会导致其抗药性的产生。目前,七星瓢虫的饲养以昆虫材料为主,辅以人工饲料,采用低温储存,以卵卡作为商品出售。七星瓢虫的基础研究可为今后大规模运用于田间提供参考。     

避难所对七星瓢虫捕食桃蚜功能反应的影响

自然情况下的捕食是以植物为中介发生的。作者采用植物模型作为捕食环境,测试了单纯的物理因素(避难所)对七星瓢虫Coccinella septempunctata L.捕食桃蚜Myzus persicae(Sulzer)的功能反应的影响。结果表明,避难所的存在能造成七星瓢虫捕食量和捕食率极显著下降,对雄虫的影响显著比雌虫强,且在中等猎物密度时影响更为突出。Logistic回归分析发现,七星瓢虫雌虫和雄虫无论避难所是否存在,功能反应类型均为HollingⅡ型。避难所不存在的情况下,雌、雄成虫的圆盘方程分别为N a=1.0259 N0/(1+0.003078 N0)和N a=0.9246 N0/(1+0.002127 N0),避难所存在的情况下,其圆盘方程分别为N a=0.9500 N0/(1+0.00342 N0)和N a=0.6463N0/(1+0.002262 N0)。避难所的存在能导致两性成虫瞬时攻击率极显著下降,但仅雄虫处置时间极显著延长,说明雄虫在环境异质性较高时捕获猎物更困难。     

Colonization of Coquillettidia linealis (Skuse) with reference to other Coquillettidia and Mansonia species

The immature stages of Coquillettidia and Mansonia mosquitoes are cryptic and spend the duration of their development attached to the tissues of subsurface aquatic plants. This obligatory association makes them difficult to collect and has precluded detailed investigation of the biology of Coquillettidia linealis, a species of significant pest and vector status in Australia, as well as other species in the genus Coquillettidia in Australia and elsewhere. This paper describes the first successful establishment and maintenance of a colony of Cq. linealis. Blood‐seeking wild adults were collected and induced to oviposit under laboratory conditions, where methods were developed to rear larval populations to adult maturity in a colony that was maintained through eight successive generations. Colonies of Coquillettidia xanthogaster and Coquillettidia sp. nr crassipes were also established and reared through at least six generations and five generations, respectively, while two species of Mansonia, Mansonia uniformis and Mansonia septempunctata, were also reared successfully for six and two generations, respectively.     

Adaptations of Coccinella magnifica Redtenbacher, a Myrmecophilous Coccinellid, to Aggression by Wood Ants (Formica rufa Group). I. Adult Behavioral Adaptation, Its Ecological Context and Evolution

Coccinella magnifica is an obligate associate of Formica rufa-group ants. The congener Coccinella septempunctata can serve as a model for its nonmyrmecophilous ancestor. Formica rufa behavior toward these two ladybirds, and their behavior, was compared. Although C. magnifica was rarely attacked on ant trails, it was usually attacked on tended aphid colonies. Coccinella septempunctata was more readily attacked. The two ladybirds' behavior was similar on trails, but C. magnifica used more defense and C. septempunctata more rapid escape behavior on aphid colonies. Only C. magnifica fed upon tended aphids. Chemical adaptation to overcome ant aggression probably exists in C. magnifica, but it possesses almost no novel behaviors to counter ant aggression. Instead, modifications have occurred in the expression of behaviors present in C. septempunctata.