Dosage reduction to improve the selectivity of deltamethrin between aphids and coccinellids in cereals

The toxicity of the pyrethroid insecticide deltamethrin to a cereal aphid and a coccinellid beetle predator was assessed. Deltamethrin gave effective aphid control in winter wheat at dose-rates of 6.25, 3.13 and 1.56g a.i./ha. The direct exposure of adultCoccinella septempunctata L. (Coleoptera: Coccinellidae) to spray drops was estimated at a range of positions in a cereal crop canopy from volumetric analysis of fluorescent tracer deposits. These measurements were used to calculate exposure to deltamethrin at the three experimental dose-rates. Observations of coccinellid beetle distribution through a cereal crop canopy permitted a realistic range of direct contact doses tobe calculated and the toxic effects of these levels of exposure to be predicted from laboratory dose-response data. Estimated beetle mortalities from direct exposure were 19, 8 and 3% at the three experimental dose-rates.In situbioassays with adultC. septempunctata which exposed beetles continuously to deltamethrin residues on flag leaves, resulted in 100, 94 and 39% mortality respectively at these dose-rates during the 10 days after spray application. Additionalin situ bioassays exposed beetles to deltamethrin residues on flag leaves for 24 h and then transferred surviving beetles to the soil under the cereal crop canopy for a further 9 days. This resulted in 89, 69 and 29% beetle mortality respectively at the three dose-rates. Mortality predictions combining both direct contact and residual exposure were made for the three dose-rates.to determine the maximum impact of summer sprays of deltamethrin on adult coccinellid populations in cereals. These worst case predictions suggested that a reduction in dose-rate by as much as three quarters of the recommended application rate in UK cereals may be necessary to preserve approximately 60% of adultC. septempunctata in the crop over the 10 days after a deltamethrin spray application. The methodology described may be appropriate for estimating selective dose-rates for key enemies in a range of crops.     

七星瓢虫和异色瓢虫四变种成虫对茶蚜蜜露的搜索行为和蜜露的组分分析

采用培养皿 ,1承接茶蚜自然分泌蜜露 ;2收集蜜露浓缩后点于培养皿中心。逐头释放瓢虫于分别盛有这 2类蜜露的培养皿中心进行生物测定 ,两个试验均证明 :1蜜露强烈地吸引七星瓢虫和异色瓢虫 ,随着蜜露浓度呈梯度地增大 ,搜寻时间极显著地延长 ( P<0 .0 1 ) ;2蜜露可激发瓢虫的搜索行为由广域搜索型转换为地域集中搜索型。前 0～ 5s局限在较小范围内不断地转向 ,即搜索速度小 ,转动角度大。七星瓢虫和异色瓢虫显明变种最敏感 ,搜索和滞留时间也最长。用高效液相色谱定性定量地分析出蜜露中有茶氨酸等 1 3种氨基酸和蔗糖等 7种糖分。     

An index model on predatory effect of female adults of Coccinella septempunctata L. on Macrosiphum euphorbiae Thomas

Abstract:  The predatory effect of female adults of Coccinella septempunctata L. (Coleoptera: Coccinellidae) on aphid Macrosiphum euphorbiae (Thomas) was examined under laboratory conditions, in controlled environmental chambers. This study took place on single rose leaves in transparent small plastic cages at varying proportions of predator/number of aphids. Coccinella septempunctata proved to be an effective predator for the biological control of M. euphorbiae under controlled conditions in closed environments. It is proposed to use starved adult females of C. septempunctata in biological control programmes in greenhouses, as a specialized predator of M. euphorbiae in proportions near 1 : 35 predator/aphids. The percentage of aphids that may escape was correlated to the hunger satiation of the predator and the total number of aphids, and the theoretical models describing the predator's behaviour under controlled conditions were defined.     

Interference competition between ladybird beetle adults (Coleoptera: Coccinellidae): effects on growth and reproductive capacity

Cage experiments were used to determine the minimum number of Aphis fabae Scopoli that females of the Azorean native ladybird beetle Coccinella undecimpunctata L. require per day to achieve maximum fecundity and to assess the effects of interference competition from conspecific and heterospecific [Harmonia axyridis (Pallas)] adult ladybirds on its growth and reproduction. The number of A. fabae at which females of C. undecimpunctata ate most aphids, achieved maximum reproduction and maintained their body weight, was 200. The presence of H. axyridis adults, unlike the presence of C. undecimpunctata, significantly affected the reproductive numerical response of C. undecimpunctata even though the resource was not in short supply. The results suggest that interference competition with heterospecifics may adversely affect the reproductive capacity of C. undecimpunctata. Based on previous results and those reported here, we suggest that the introduction of H. axyridis could endanger the population abundance and/or result in the competitive displacement of C. undecimpunctata from the Azorean ecosystem.     

Ovarian dynamics and oosorption in two species of predatory lady beetles (Coleoptera: Coccinellidae)

Abstract Ovarian development and oviposition dynamics of two species of lady beetle, Coccinella septempunctata L. and C. transversoguttata richardsoni Brown, are examined in laboratory experiments in which pea aphids (Acyrthosiphon pisum Harris) are provided ad libitum and then removed. Both species respond to prey removal by stabilizing at lower body weights, and by laying progressively fewer and smaller eggs of reduced viability, until oviposition ceases altogether after several days of starvation. Dissections of females after prey removal reveal similar patterns of oosorption in both species. However, C. septempunctata reduces oviposition more rapidly after prey removal than does C. transversoguttata. When prey are again provided, C. septempunctata soon lay as many eggs as previously but C. transversoguttata lay fewer. Females, especially of C. septempunctata, that stop producing and resorb eggs in the absence of prey lay more eggs subsequently than do females that feed continually on prey provided ad libitum and lay eggs throughout the experiment. Thus, although both species are responsive to a rapid change in prey availability, C. septempunctata appears to be especially responsive. Rapid responses to changes in prey availability may contribute to the greater abundance and reproductive success of this introduced species relative to the native C. transversoguttata in western North American alfalfa fields that exhibit widely varying pea aphid densities. However, both species engage in oosorption as a means of reserving resources under poor prey conditions and enhancing future reproductive effort when prey conditions improve.     

人工饲料中添加脂类和昆虫保幼激素类似物对七星瓢虫取食和生殖的影响

本文定量测定在人工饲料中加入埴物油和ZR512对七星瓢虫成虫(第一代)的生殖、摄食、生长、食物利用和转化的影响。结果表明:成虫取食加0.1%橄榄油和ZR512的人工饲料时产卵率能达到96.7%产卵前期为8天左右。如果在此基础上分别添加1%的玉米油或豆油时能促进雌虫产卵量的进一步增加,成虫的增重百分率随着生长天数增加持续上升,取食这种人工饲养的成虫除产卵量外,在体重、产卵前期、产卵率三方面都达到或接近取食蚜虫时的水平。 人工饲料中加入橄揽油能刺激成虫的取食,在此基础上加入玉米油或豆油能使食物转化效率显著地提高。人工饲料中加入ZR512时能阻止或打破雌虫的生殖滞育,促进生殖活动。     

La répartition spatiale des différents stades de Coccinella septempunctata dans un champ de blé: variation au cours de la saison

Résumé Au début du printemps les adultes de Coccinella septempunctata L. (Col., Coccinellidae) issus des sites d'hivernation, les larves et les nymphes qui en proviennent, fréquentent le sol et les parties basses du blé. En juin, les adultes nés dans le champ et leur descendance sont dispersés sur toute la hauteur des talles bien qu'une fraction non négligeable de leur population se rencontre à l'extrémité supérieure. La plupart des pontes sont déposées sous les mottes de terre, les pierres et les petites adventices qui constituent des sites privilégiés. Ces variations de la distribution de cette coccinelle peuvent être mises en relation avec le climat, en particulier la température, avec la thermophilie de cette espèce et avec la répartition sur les différentes parties des talles des 3 espèces de puceron qui se succèdent au cours de la saison. Ces observations sont importantes à considérer lors du choix ou de la mise au point d'une méthode d'échantillonnage.     

外源保幼激素类似物对七星瓢虫血淋巴中卵黄原蛋白含量的影响

本文以不同剂量的保幼激素(JH)类似物点滴七星瓢虫雌虫,测定了生殖过程中卵母细胞的长度及血淋巴中卵黄原蛋白(Vg)及总蛋白的含量.结果表朋:1.点滴不同剂量ZR-512于虫体后,皆可促进卵母细胞生长,尤以点滴100μg效果最为明显.2.点滴ZR-512后可以促进Vg合成,血淋巴中Vg含量皆明显提高,以点滴100μg效果最好.3.点滴不同剂量ZR-512后,雌虫血淋巴中总蛋白含量变化与Vg含量变化的规律相似.4.血淋巴中的Vg含量与卵母细胞长度有一定相关性.另外,讨论了不同剂量外源JH类似物对CA活性、内源JH水平、Vg含量以及卵母细胞生长的影响.     

七星瓢虫的卵黄发生:植入雄虫的卵巢中卵黄原蛋白的合成

为了证实七星瓢虫的卵巢能合成卵黄原蛋白, 并查明雄虫体内是否具有卵黄发生所必需的激素环境, 我们将刚羽化雌虫的一侧卵巢或数个卵巢管植入雄虫体内.移植的卵巢或卵巢管在雄虫体内能够发育, 其卵母细胞能沉积卵黄, 一部分可达成熟.体外培养证明移植的卵巢可合成卵黄原蛋白, 但受体雄虫的脂肪体不合成卵黄原蛋白, 而且其血淋巴中也不存在这种蛋白.用保幼激素类似物ZR-512处理受体雄虫, 可促进移植卵巢的发育, 但不能诱导其脂肪体合成卵黄原蛋白.此结果表明, 象大多数昆虫一样, 七星瓢虫的卵黄发生的性二型现象表现在激素的靶组织——脂肪体, 而不是激素本身.     

草间钻头蛛等对茶尺蠖的捕食功能反应研究

应用二次正交旋转组合设计方法,研究了茶园生态系统中3种捕食性天敌（草间钻头蛛、大草蛉和中华通草蛉）对茶尺蠖的捕食功能性反应。同时分析了猎物密度、捕食者自身密度、种内以及种间干扰对捕食功能的影响。结果指出：3种天敌及茶尺蠖自身密度的变化对于茶尺蠖的被捕食量存在明显的影响,其中草间钻头蛛密度的变化对总捕食量的影响最大。并且这3种天敌的种间和种内均存在着一定的干扰效应。