首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
自1976年首次在秦皇岛海岸发现七星瓤虫的群聚现象以来,又经过连续8年的广泛研究,进一步讨论了七星瓤虫在黄、渤海域的群聚范围、群聚数量、群聚规律以及迁飞等问题。本文的重点是试图从数学上论证七星瓤虫的迁飞,并进一步预测预报七星瓤虫的群聚日期,以便为群聚七星瓢虫的利用奠定基础。 根据可能有关的因子设64个自变量,2个因变量,通过反复计算,大量筛选可能与虫情有关的气象因子,结果入选的气象因子说明,群聚瓢虫是迁飞过程中迫降入海,并由风浪推上海岸的。经过用双层筛选逐步回归和逐步判别两种数学方法去筛选自变量,结果基本上是一致的。因此从定量角度对七星瓢虫的群聚和迁飞给出了论证。并说明七星瓢虫的群聚与近期气象条件密切相关,可以利用短期或中期气象预报代入判别式进行群聚的预测预报。  相似文献   

2.
七星瓢虫雌成虫咽侧体的活性   总被引:1,自引:1,他引:0  
以短期体外放射化学测定法测定了七星瓢虫雌成虫的咽侧体(CA)活性。结果表明,七星瓢虫的CA在TC 199培养液中培养时活性最高。在最适培养条件下CA合成保幼激素(JH)的速度在1—4小时呈直线增加。 七星瓢虫雌虫生殖期CA的活性变化与卵黄发生有相关性。羽化初期CA活性很低,羽化后4—8天CA活性增加,卵母细胞内卵黄沉积开始增多;羽化后8—12天CA活性高峰出现,此时卵母细胞内有大量卵黄沉积;羽化后12—15天CA活性下降,卵完全成熟并陆续出现产卵个体。 食料对七星瓢虫成虫的卵黄发生的影响:取食人工饲料雌虫的CA活性增长缓慢,直至羽化后15天CA活性仍很低,因而抑制了卵黄原蛋白的合成,使卵巢发育缓慢。此种雌虫中CA活性高峰的出现比取食蚜虫的延迟约2倍,前者的产卵前期也较后者延长约2倍。  相似文献   

3.
Summary Six of the eight species of beetles at South Georgia, the southernmost beetles of the world, were investigated in outdoor arenas with pitfall traps for their diel patterns of locomotory activity. All of them were clearly nocturnal, the only exception being a small staphylinid which appeared to be active throughout the day and night. Activity of the other species was restricted to the dark period of the night, with little activity during twilight. Peak activity occurred before or at midnight. Activity was clearly correlated with temperature. Diurnal activity may involve a risk of overheating and desiccation, but could also have evolved in the past due to bird predation, which today is very low in the study area.  相似文献   

4.
SUMMARY: An apparatus is described in which sufficient microbe-free timothy grass to make 'silage' on a laboratory scale was grown. In one experiment the chemical changes which occurred during the period of ensiling were measured. They could be attributed only to the metabolism of the plant cells.  相似文献   

5.
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。  相似文献   

6.
Wire-worms rarely occur in permanent arable land in sufficient numbers to cause serious damage to crops. Various workers (e.g. Roebuck, 1924; Hawkins, 1936; Miles & Cohen, 1941) have noted the reduction in numbers of wireworms in successive years on ploughed-out grassland. At Rothamsted reductions of 62 % in one year and 85 % in two years were recorded on plots on Highfield. This reduction is certainly due in part to the exposure of wireworms to their natural enemies and to the direct effect of disturbance by implements of cultivation. It has also frequently been suggested that the beetles prefer to oviposit on grassland or clover leys and to a lesser extent on cereal crops (Bryson, 1930; Rawlins, 1934; Balachowsky & Mesnil, 1935; Miles & Cohen, 1938). A laboratory experiment to test this point was accordingly carried out in June 1940.  相似文献   

7.
纵坑切梢小蠹蛀梢期空间分布   总被引:10,自引:1,他引:9  
叶辉  李隆术 《昆虫学报》1994,37(3):311-316
在昆明地区,纵坑切梢小蠹(Tomicus piniperda)成虫蛀梢多集中在蛀干木附近。 种群密度以蛀干木为中心向周围呈指数递减,散布半径约30m。在蛀梢过程中,该种群逐渐向新区扩张。在树冠内,纵坑切梢小蠹主要分布在4-10轮枝上。第7轮枝虫口百分率最高。6-7轮枝受害率最大。 树冠上层受害较其下层严重。从树冠水平层次考察,树冠外层虫量相对集中,约为树冠中、内层虫量之和。 树冠内层虫量最少。纵坑切梢小蠹在树冠内的种群分布系由梢径、种群密度、蛀梢行为、降落方式、光照等因素综合影响的结果。  相似文献   

8.
纵坑切梢小蠹蛀梢期空间分布   总被引:11,自引:0,他引:11  
在昆明地区,纵坑切梢小蠹(Tomicus piniperda)成虫蛀梢多集中在蛀干木附近。种群密度以蛀干木为中心向周围是指数递减,散布半径约30m。在蛀虹梢过程中,该种群逐渐向新区扩张。在树冠内,纵坑切梢小蠹主要分布在4—10轮枝上。第7轮技虫口百分率最高。6—7轮枝受害率最大。树冠上层受害较其下属于重。从树冠水平层次考察,树冠外层虫量相对集中,约为树冠中、内层虫量之和。树冠内层虫量最少。纵坑切梢小蠹在树冠内的种群分布系由梢径、种群密度、蛀梢行为、降落方式、光照等因素综合影响的结果。  相似文献   

9.
Abstract:  Pollen beetles ( Meligethes aeneus F) are common pests of oil-seed rape crops ( Brassica napus L) in Denmark, causing serious yield losses (>80% reduction). In consequence, the crop is treated with pesticides in most years. To estimate the need for insecticide treatment it is desirable to develop a method, which, in a simple and very labour-saving way, can estimate the number of pollen beetles in oil-seed rape crops. Incidences of pollen beetles were recorded in 105 spring and winter oil-seed rape fields. From the coherent values of the percentage of plants infested with pollen beetles ( Y ) and the number of pollen beetles per plant ( X ) the following model was deduced: Y  = 43.3 ×  X 0.47.  相似文献   

10.
Seasonal selection acting on the melanic polymorphism in the two-spot ladybird Adalia bipunctata was investigated in The Netherlands. An increase in melanic frequency over the spring-summer reproductive period was quantified. The selective advantage gained by melanics averaged 9%, but significant heterogeneity occurred between populations. Adult hibernation behaviour is described. The beetles when outdoors show a highly clumped distribution both between and within trees. The distribution of the morph classes between aggregations is random. Survivorship in a hibernating cohort (initial n= 1898) on a grid of 70 lime trees near Utrecht was monitored by making three counts over the winter of 1981–1982. Intense selection favouring each melanic morph occurred during December and January. The relative fitness of non-melanics was 0.55 (melanics =1). The discovery of dead beetles in late January (about 5% of total losses) and the absence of spatially density-dependent mortality were consistent with a climatic stress rather than selective predation. The period of selection was associated with very cold temperatures averaging up to 4°C below normal and an overall mortality of nearly 75%. There was no change in morph frequency, near normal temperatures and a lower mortality from February to early April. Examination of groups of nearby trees in late January strongly suggested that similar differential mortality had occurred except on some willows. This difference was probably due to the more protected hibernation sites available on these trees. Samples of hibernating cohorts at three other sites showed no evidence of differential mortality. Laboratory experiments with hibernating beetles found no difference in survivorship or rate of weight loss between starved non-melanics and melanics in temperature regimes with and without periods of adult activity. It is concluded that the intense winter selection on the study limes is probably exceptional. Examination of changes in morph frequency through the annual cycle suggests that at some sites the selection favouring melanics during reproduction is counterbalanced by selection against melanics in late summer or early autumn. The results are discussed in relation to mathematical models of cyclical selection and to other field studies including that of Timoféeff-Ressovsky (1940), who found large decreases in melanic frequency during hibernation in Berlin.  相似文献   

11.
A single colony of the non-native grass Poa pratensis L., which was introduced inadvertently to Cierva Point, Antarctic Peninsula, during the 1954–1955 season, was still present during a survey in February 2012, making it the longest surviving non-native vascular plant colony known in Antarctica. Since 1991, the grass cover has roughly tripled in size, with an annual increase in area of approximately 0.016 m2, and an estimated maximum radial growth rate of 1.43 cm y?1. However, it remains restricted to the original site of introduction and its immediate surroundings (c. 1 m2). Annual flowering of the plants occurred during the 2010/2011 and 2011/2012 seasons; however, there has been no seed production and only incomplete development of the sexual structures. Current environmental conditions, including low temperatures, may inhibit sexual reproduction. Lack of effective vegetative dispersal may be influenced by the low level of human activity at the site, which limits opportunities for human-mediated dispersal. Although P. pratensis has existed at Cierva Point for almost 60 years, it has not yet become invasive. Scenarios for the potential future development of the species in Antarctica and the associated negative impacts upon the native vegetation from competition are discussed in the context of regional climate change. Finally, we describe the environmental risk presented by P. pratensis and argue that this non-native species should be eradicated as soon as possible in accordance with the Protocol on Environmental Protection to the Antarctic Treaty.  相似文献   

12.
Daily analysis of anther samples during flower development hasenabled an estimation of the duration of defined developmentalperiods in pollen of the grass Phalaris tuberosa. A similarsequence of pollen development has been established for ryegrass,Lolium perenne, where changes in activity of wall enzymes havebeen followed using quantitative cytochemical methods. Acidphosphatase, an intine enzyme, showed two periods of activity:during the vacuolate period corresponding to deposition of theintine polysaccharides; and in the maturation period correspondingto cytoplasmic activity. Non-specific esterase showed greatestactivity in the parietal tapetal cells until their dissolutionearly in the vacuolate period when an increase in pollen-associatedactivity occurred. These changes provide additional evidencefor the transfer of tapetal proteins to exine sites. Lolium perenne L., Phalaris tuberosa L., ryegrass, canary grass, pollen development, quantitative cytochemistry, enzyme activities, acid phosphatase, esterase  相似文献   

13.
蓖麻蚕微孢子虫的超微结构研究   总被引:2,自引:2,他引:0  
谢伟东 《动物学报》1989,35(4):345-347
用电镜技术研究蓖麻蚕微孢子虫各发育阶段的超微结构,发现其裂殖体和母孢子具双核,其细胞核由双层单位膜所包裹,核具半圆形的纺锤空斑,细胞质中有内质网和丰富的核糖体,但无线粒体。成熟的孢子壁由外壳、内壳及孢子膜组成,孢子器具有片层结构的极质体和后液泡,极丝为10—11圈,孢质含有核糖体和一对细胞核。  相似文献   

14.
The influence of temperature on the diurnal activity of five species of aphidophagous lady beetles (Coleoptera: Coccinellidae) was investigated between 0700 and 1900 h in chili (Capsicum annuum L.) agroecosystems and neighboring vegetation (goose grass, Eleusine indica L.). The lady beetle species observed were Menochilus sexmaculatus Fabricius, Coelophora inaequalis F., Coccinella transversalis F., Harmonia octomaculata F. and Coelophora bissellata Mulsant. More lady beetles (of all species) were found during cooler periods (at 0700, 0900, 1100, and 1900 h). The diurnal pattern of lady beetle adult was temperature dependent. On chili plants, numbers were higher at temperatures between 22 to 30 °C (at 0700, 0900, 1100 and 1900 h) and numbers decreased when temperatures were above 30 °C. When temperature was above 30 °C under the chili plant canopy, numbers were higher in neighboring goose grass, where temperatures were cooler (< 30 °C). Numbers of all species were negative correlated between chili plant and goose grass.  相似文献   

15.
Attempts to measure the dispersion, population density and longevity of blowflies are described. The experiments were made at Aber, Caernarvonshire, in 1943 on a narrow strip of coastal farm land (if x f ml.). Two liberations of laboratory-bred Lucilia sericata (Mg.) were made. On the second occasion 286 flies of each sex were marked, and nine males and nineteen females were captured, the last capture occurring 15 days after liberation. The population density of this species was estimated to be approximately seven males and sixteen females per acre for the 840-acre strip on the day of the second liberation.
On 24 days during the period 20 August–20 September 1943, field-caught L. caesar (L.) females were marked, and trapping both by meat and chemical baits was continued for a further 3 weeks. 3600 females were marked, 847 being recaptured at least once, and sixteen on at least four occasions. In the later part of the blowfly season, a life of 5–6 weeks is apparently not unusual for L. caesar females. The population drawn upon by the traps at the liberation centre fluctuated between 700 and 30,000 during the 4-week period. This may have represented a very localized concentration equivalent to 6–238 females per acre. Dispersion of marked L. caesar was low. On the assumption of a maximum spread of 5 miles, some 63 % of the marked flies remained within 4 mile of the liberation centre.  相似文献   

16.
Aphis fabae gynoparae occurred in the same large proportion in simultaneous collections of all aphids alighting and probing on, and taking off from, a host plant (spindle) and a non-host (peach), and behaved similarly when approaching and leaving them in the same conditions. Most alighters took off again from leaves of both kinds within a few minutes, staying longer and probing more times on the host. In atmospheric conditions favouring local 'hovering' instead of dispersal, flying and alighting aphids became concentrated around host plants, not through any specific attraction to them, but apparently because more aphids had accumulated upon them and were now taking off.
Brevicoryne brassicae occurred in the same large proportion in simultaneous collections of aphids alighting on a host plant (cabbage) and a non-host (sugar beet). No satisfactory evidence was found of preferential alightment on cabbage and there were indications of preferential alightment on the non-host. A very small minority of the A. fabae and B. brassicae that alighted on their hosts stayed there long enough to larviposit. This minority was rather larger among alighters late in the day, but in the absolute sense, more colonization occurred during earlier periods when more aphids arrived.
The intensely dispersive type of host-finding behaviour in Myzus persicae, A. fabae and B. brassicae may be common among Aphididae. It seems ideal for the dissemination of non-persistent plant viruses, more particularly among the less-favoured host plants of each aphid. The tendency to commensal association between virus and vector provides an ecological framework which may govern the incidence of virus-vector specificity and symbiosis.  相似文献   

17.
《Chronobiology international》2013,30(7):1290-1306
Circadian rhythms in behavior and physiology are very different in diurnal and nocturnal rodents. A pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus is responsible for generating and maintaining circadian rhythms in mammals, and cellular and molecular rhythms within the SCN of diurnal and nocturnal rodents are very similar. The neural substrates determining whether an animal has a diurnal or nocturnal phase preference are thus likely to reside downstream of the SCN. The ventral subparaventricular zone (vSPVZ), a major target of the SCN that is important for the expression of circadian rhythmicity in nocturnal lab rats (Rattus norvegicus), exhibits different rhythms in cFos expression in diurnal Nile grass rats compared to lab rats. We examined the effects of chemotoxic lesions of the cFos-expressing cells of the vSPVZ on activity rhythms of grass rats to evaluate the hypothesis that these cells support diurnality in this species. Male grass rats housed in a 12:12 light:dark (LD) cycle were given bilateral injections of the neurotoxin n-methyl-D-L-aspartic acid (NMA) or vehicle aimed at the vSPVZ; cells in the SCN are resistant to NMA, which kills neurons in other brain regions, but leaves fibers of passage intact. vSPVZ-damaged grass rats exhibited highly unstable patterns of activity in constant darkness (DD) and in the LD cycle that followed. However, crepuscular bouts of activity could be seen in all animals with vSPVZ lesions. Damage to the vSPVZ reduced cFos expression in this area but not in the SCN. Using correlational analyses, we found that the number of cFos-ir cells in the vSPVZ was unrelated to several parameters of the activity rhythms during the initial post-surgical period, when animals were in LD. However, the number of cells expressing cFos in the vSPVZ was positively correlated with general activity during the subjective day relative to the subjective night when the animals were switched to DD, and this pattern persisted when a LD cycle was reinstated. Also, the number of cFos-ir cells in the vSPVZ was negatively correlated with the strength of rhythmicity in DD and the number of days required to re-entrain to a LD cycle following several weeks in DD. These data suggest that the vSPVZ emits signals important for the expression of stable diurnal activity patterns in grass rats, and that species differences in these signals may contribute to differences in behavioral and physiological rhythms of diurnal and nocturnal mammals. (Author correspondence: )  相似文献   

18.
Abstract:  At 15 commercial highbush blueberry farms, fields where row middles were tilled had 72% lower larval density of Popillia japonica than fields with grass in row middles. Popillia japonica larval populations were similar in the perimeters of tilled and untilled fields. Soil parameters measured in these sites were not correlated with larval density of P. japonica. Samples of adult beetles on bushes showed that they were significantly less abundant in tilled fields compared with fields with grass in the row middles. The abundance of larvae inside fields during the spring was significantly correlated with early, but not late summer abundance of adult beetles on bushes. Comparisons of different tillage timings showed that grassy plots between rows of blueberry bushes that were tilled in spring and kept bare all year round had lower abundance of P. japonica larvae than those that retained perennial ryegrass. The effect of tillage timing on larval abundance was not consistent across 2 years, but most timings caused similar reduction in P. japonica larval density in the row middles. Tillage in the spring and in the autumn caused 50.5% and 68.8% reduction of larval density in each year respectively. These results indicate that tillage can reduce P. japonica larval and adult abundance in highbush blueberry fields.  相似文献   

19.
在真核细胞中,除了线粒体和叶绿体ATPase的功能是合成ATP外,其余部位ATPase是水解ATP以获取生物能量的代谢酶,在生物体细胞内广泛存在。探索ATPase在细胞中的分布状态是研究细胞生理状态的一种重要手段。ATPase在细胞中的多少可反映出细胞当时的生活状态,这一特征已被初步用于探索小麦和水稻雄性不育的细胞生物学研究中,希望通过比较可育花药和不育花药中ATPase的分布差异寻找雄性不育的机理,发现  相似文献   

20.
Otiorrkynchus clavipes Bonsd. is a serious pest of strawberries around Cheddar, Somerset. The weevils nibble the foliage, the larvae eat the roots of the plants, and burrow into the rootstock.
The beetles appear in two waves, pupating in the autumn and emerging en masse in the spring, or pupating in the late spring and summer and emerging in succession between mid-June and the end of August. Both sexes are found and can be distinguished by the posterior thoracic sterna, which are concave in males and convex in females. Mating is alternated with egg-laying and the beetles lay between 100 and 300 eggs per female. On emergence the beetles eat voraciously, and roughly one egg is laid for every 10 sq.mm. of leaf consumed. Both parthenogenetic and fertile eggs are laid and hatch in between 17 and 24 days.
The larvae burrow rapidly when hatched and can only penetrate soil spaces which will admit their head capsules. The distribution of head capsule widths in mixed populations of larvae of all ages shows there are five instars. While feeding, the larvae are clustered within the root range of the plants and find their way to their food from plant to plant, guided by the exudates from the strawberry roots. As the larvae grow older they descend in the soil and turn to white soft pupae in smooth earthen cells 6–8 in. below the plants.
Adult damage to foliage is unimportant but larval damage to roots is serious and has been largely responsible for restricting the effective life of the strawberry beds to at most 2 years. Although weevil attack can be avoided by growing the crop in a 1-year rotation, control is difficult owing to the intensive cropping, which creates the most suitable conditions for the spread of the infestations. The adults are killed with 10% DDT dust; and the larvae by DDT and BHC preparations poured on to the soil, at a pint per plant, or by DD injection. The limitations and possibilities of various methods of control are discussed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号