Wheat bulb fly, Leptohylemyia coarctata Fall., and its effect on the growth and yield of wheat

In two experiments done in successive years to compare the growth and yield of Cappelle wheat either protected from or exposed to attacks by larvae of wheat bulb fly, the plots were previously fallowed, but egg laying was prevented on half of each plot by using Polythene soil covers. In the first season wheat was sown at the end of October, November and December and in the second season in late October and in early January, when there were two sowings, one with and one without a spring application of herbicide. The infestation rate was 1·1-1·7 million eggs per acre, typical of a moderate attack. Larvae had little effect on the yield of October-sown wheat as the plants had two shoots each when first attacked and few were killed. On plots sown late, yield was decreased by up to 22%, as plants had only a single shoot when attacked and many were killed. The main effect of wheat bulb fly was to reduce the number of ear-bearing shoots by killing plants and restricting the production of new shoots. Surviving plants partially compensated by producing more ear-bearing shoots with heavier ears and slightly heavier seeds than normal. Killed plants were not distributed uniformly but were often in patches several feet across. Wheat on the attacked plots ripened more slowly and unevenly than on the unattacked plots. Weather affects the growth of the plants and activity of the larvae and thus partly determines percentage shoot survival.     

Possible impact of global warming on cabbage root fly (Delia radicum) activity in the UK

A program for simulating the patterns of egg-laying by populations of the cabbage root fly was used to model the effects of global warming on future cabbage root fly attacks. An increase of 3°C in mean daily temperature would cause the cabbage root fly to become active about a month earlier in the year than at present. Under such conditions, the emergence of flies from the overwintering population would be less synchronised, as the completion of diapause and post-diapause development would occur at the same time in different individuals within the population. However, there would continue to be only three generations of fly each year, even in the south of England. With temperature increases of 5°C or 10°C, the fly would complete four generations each year and aestivation would seriously disrupt egg-laying. These rises in temperature would have a major impact on cabbage root fly activity and would require new strategies for controlling this pest.     

An investigation of the differential performance of clones of the aphid Sitobion avenae on two host species

Individuals of the grain aphid Sitobion avenae were collected from wheat and cocksfoot stands around Hampshire, UK, during March and April 1994. Eight wheat and eight cocksfoot aphid clones were chosen on the basis of readily distinguishable RAPD-PCR fingerprint profiles. The performances (weight, fecundity and survival) of successive generations of each of these clones were then carefully monitored in the laboratory as new generations of aphids were transferred either to winter wheat or to cocksfoot in planned sequences. Even those clones that were originally caught on the same host showed significant variability in performance. Clones generally performed better on their host of origin than they did on the alternate host, and they performed less well on the alternate host compared to the clones that had originated there. A comparison of the performance of third generation aphids with first generation aphids showed that the experience of the mother in the second generation often influences the subsequent performance of their offspring. As the sequence of host transfers had more effect on the performance of wheat clones than cocksfoot clones, it is likely that wheat clones are more specialised, such that wheat is a satisfactory host for cocksfoot clones but not vice versa. The study provides evidence of genetic variation in performance on host and evidence for clonal adaptation to particular host species. This adaptation may well be a major cause of the observed consistent genetic differentiability of populations of S. avenae found on wheat and roadside grasses in early spring in southern England.     

Distribution,population dynamics and damage of Hessian fly,Mayetiola destructor (Diptera: Cecidomyiidae) in North Tunisia

A three years survey and monitoring studies (2013–2014–2015) were carried out through 4 regions of north Tunisia in order to follow the evolution of the distribution, the frequency of occurrence and damage caused by the Hessian fly Mayetiola destructor (Say) to bread wheat (Triticum aestivum L.) and durum wheat (Triticum durum Desf). Moreover, the effectiveness of resistance genes H3, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15, H22, H23, H25 and H26 to protect wheat from Hessian fly attack was assessed in natural field and under controlled laboratory conditions at INRAT-Kef Station. Results showed that Hessian fly was detected in 60.33% and 51.5% of all sampled durum and bread wheat fields, respectively. This pest was more frequent with a higher percentage of infestation in semi-arid regions. Indeed, during 2013, infestation rate attained 12.39% in Kef region against 0.9% registered in Bizerte region. In order to update information about the annual number of generations, we surveyed the population dynamic of Hessian fly in Kef region. Three generations of the fly were counted annually on wheat, with two complete and one incomplete generation. This insect affects host plant growth at different developmental stages. Plant height was the most affected parameter followed by shoot dry weight and tiller number. Field investigations on host resistance revealed that among the 16 tested resistance genes, and only three were strictly effective (H22, H25 and H26). The resistance genes H5, H9, H13 and H9H13 have also conferred high levels of protection against Hessian fly. This work indicated that H22, H25 and H26 genes could be incorporated into Tunisian wheat varieties and released to farmers to manage the threat due to Hessian fly attacks.     

小波分析二点委夜蛾发生规律

二点委夜蛾Proxenus lepigone(Moschler),属鳞翅目夜蛾科,主要分布于日本、朝鲜、俄罗斯和欧洲等地。我国于2005年7月在河北省夏玉米田首次发现。近年来,该虫发生范围不断扩大,为害程度日益加重。2011年二点委夜蛾在我国夏玉米产区严重暴发,虫情涉及6省47市302个区(县),面积近220万hm2。山东省2007年首次在德州市发现该虫为害玉米,2011年全省17个地市普遍为害严重。为更准确地确定该虫的发生代次、每代各虫态发生历期、发生盛期、发生高峰日等信息,适时准确监控发生时期,本文采用symlets小波函数变换滤除高频信息,对山东省多地点二点委夜蛾成虫诱虫数据进行分析,结果显示,二点委夜蛾在山东省一年发生4代,越冬代、1代、2代、3代,始见蛾日在3月底—4月上旬,越冬代成虫发生期在3月底至4月上中旬,1代发生期在4月上旬至6月中下旬,2代发生期在6月中旬至8月上中旬,3代发生期在8月上旬至9月中下旬,越冬代幼虫发生期在9月中旬至10月中下旬,10月下旬左右老熟幼虫做茧越冬。另外,通过调查和室内观察还发现高温环境不利于二点委夜蛾幼虫生长发育,7—8月份高温期,成虫致畸率较高。     

Changes in phytohormones and fatty acids in wheat and rice seedlings in response to Hessian fly (Diptera: Cecidomyiidae) infestation

Phytohormones and fatty acids (FAs) play important roles in plant resistance to insects and pathogens. In this study, we investigated the similarities and differences in the accumulations of phytohormones and FAs in the resistant wheat (Triticum aestivum L.) 'Molly' and the nonhost rice (Oryza sativa L.) 'Niponbare' in responses to Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae), larval attacks. Using chemical ionization-gas-chromatography/mass spectrometry, we analyzed the concentrations of 13 phytohomones and FAs at the attack site of wheat and rice plants at 1, 6, 24, or 48 h after the initial attack. Hessian fly attack resulted in increases of salicylic acid (SA), 12-oxo-phytodienoic acid (OPDA), palmitic acid (FA16:0), but a decrease of abscisic acid in both wheat and rice plants. In addition, the accumulation of jasmonic acid (JA) increased, whereas the accumulation of cinnamic acid (CA) decreased in wheat plants, but no changes were observed in the accumulation of JA, and the accumulation of CA increased in rice plants after Hessian fly attack. However, the accumulations of benzoic acid, strearic acid (FA18:0), and oleic acid (FA18:1) increased in rice plants, but no changes were observed in wheat plants after Hessian fly attack. Hessian fly-induced changes were more rapid in wheat plants in comparison with those in rice plants. Our study suggests that SA and OPDA may be involved in resistance of wheat and rice plants to Hessian fly and that the R gene-mediated resistance responses are more rapid than nonhost resistance responses.     

A genetic polymorphism maintained by natural selection in a temporally varying environment

ABSTRACT Environments that are crowded with larvae of the fruit fly, Drosophila melanogaster, exhibit a temporal deterioration in quality as waste products accumulate and food is depleted. We show that natural selection in these environments can maintain a genetic polymorphism with one group of genotypes specializing on the early part of the environment and a second group specializing on the late part. These specializations involve trade-offs in fitness components. The early types emerge first from crowded cultures and have high larval feeding rates, which are positively correlated with competitive ability but exhibit lower absolute viability than the late phenotype, especially in food contaminated with the nitrogenous waste product, ammonia. The late emerging types have reduced feeding rates but higher absolute survival under conditions of severe crowding and high levels of ammonia. Organisms that experience temporal variation within a single generation are not uncommon, and this model system provides some of the first insights into the evolutionary forces at work in these environments.     

Observations on the biology and experiments on control of the mangold fly (Pegomyta betae Curtis) on sugar beet

The fly ( Pegomyia betae Curtis) was studied in its ecological and phenological aspects in central Nottinghamshire, and experiments on the lines of Continental workers, using sodium fluoride and molasses spray, were carried out.
It is shown that some pupae from the second generation- fail to emerge in the late summer but emerge in the spring of the following year, rather earlier than the pupae resulting from the third generation. The flies resulting from this early emergence are less fertile than those appearing later.
Methods of control discussed include cultural, biological and chemical means. Delayed drilling (not before mid-May) helps to avoid the attack of the first generation. A rapid increase in number of parasites was observed and resulted in the annihilation of a large population of the fly. Treatment with molasses/sodium fluoride bait spray gave promise of control.     

Parasitoid and inquiline attack in the galls of four alien, cynipid gall wasps: host switches and the effect on parasitoid sex ratios

1. Four alien cynipid gall wasps of the genus Andricus are established and still spreading in the British Isles. The order, according to the northerliness of their distribution boundary, is: A. corruptrix→A. quercuscalicis→A. lignicola→A. kollari. All four aliens have a sexual generation in spring on Quercus cerris (introduced to Britain) and an agamic generation in autumn on native oak species. 2. For 2 years 1994 and 1995, galls of both generations of the four alien species were sampled at eight sites from the south of England to the north of Scotland to determine the parasitoid and inquiline species that attack the new galls. The spring generations of the invading species shared a parasitoid complex of four pteromalid species. Five species of inquilines and 11 species of parasitoids emerged from the autumn galls. 3. Two colonisation events were recorded for A. lignicola and A. corruptrix. On both occasions, the spring generations were found first at the new sites, indicating that the agamic generation provides the colonisers for these invading species. After colonisation, the galls of both species were attacked by parasitoids in their first season. 4. In spring, the invading species were among the most abundant cynipids at all eight sites. By sampling the whole local community of cynipid galls, it was found that the parasitoid species attacking the spring galls of the invaders seemed to have shifted their attack to the new hosts. 5. The secondary sex ratios of the parasitoid species emerging from the sexual galls of A. quercuscalicis (the smallest of the four) showed a strong and significant male bias at all sites and in both years. Parasitoid emergence from the galls of the sexual generations of the other three species (all about equal in size) was between 60 and 70% male, and variable among sites and between years.     

DAMAGE TO WHEAT BY HELOPHORUS NUBILUS F

Helophorus nubilus F. is recorded as a serious pest of wheat in East Anglia. No previous record of serious damage has been made, but slight injury was recorded iu 1922 and 1923. Observations in a number of widely separated fields show that the intensity of attack varies with the previous cropping and a serious attack occurs most frequently after rye grass and clover. The larva causes ^Tl most damage when the tilth is loose.
Observations on the life history suggest that the species has one generation per annum. Eggs were not found, and the earliest damage to wheat was observed in January. Pupae were found in late April and early May, and adults were bred out in the laboratory at the end of May. The larval and pupal stages are described.
The authors are indebted to Dr G. H. Bates and Mr J. C. Mann of the Norfolk County Agricultural Staff, and to Mr G. W. Channon, formerly of the Cambridgeshire County Agricultural Staff, who reported insect attacks on the wheat fields visited.     

橙黄后窗网蛾的生物学初报

橙黄后窗网蛾Dysodia magnificaWhalley是油桐(Vernicia fordii(Hemsl.)Airy-Shaw)的食叶害虫,在浙江省丽水地区油桐上普遍发生。该虫1年发生3代,以蛹在土茧内越冬。越冬代成虫于次年4月中旬开始羽化,第1、2代成虫分别于6月下旬和8月下旬开始羽化。饲养中育出幼虫-蛹期寄蝇—蚕饰腹寄蝇,是橙黄后窗网蛾的一种有效天敌。     

Developmental pattern of colonies in the polystyelid ascidian,Polyandrocarpa misakiensis

Summary

The growth pattern of zooids formed asexually by budding was studied in the colonial ascidian, Polyandrocarpa misakiensis. Each colony started from a blas- tozooid (the first generation) on the glass plate in two series of experiments. To evaluate the growth of colonies, lineage of all the zooids of three successive generations was traced on photographs which were taken once a week. The zooids of the first generation produced many buds from any basal margin of the zooidal body, and those of the second generation produced a small number of buds mainly from anterior parts of the zooidal body. The zooids of the second generation produced by early budding of mother zooids were clearly more prolific than those produced by late budding. Circular colonies which developed around a zooid of the first generation consisted of stratified zones of successive generations. Each zone was composed of two subzones; the outer one mainly containing early-produced zooids, and the inner one mainly containing late-produced zooids. The zooids in the marginal area of colony are early-produced ones from generation to generation. The seawater temperature may influence the growth of zooids and/or the frequency of budding.     

Characterisation of Predator‐Directed Displays in Tephritid Flies

Flies of the family Tephritidae are known to perform a display in front of their salticid spider predators. This display involves extending the wings while the fly moves from side to side. The wings of many of fly species are banded, and in some species, these bands are thought to deter their predators by mimicking the leg patterns of salticids. However, as this display is also seen in non‐mimicking flies, there is some uncertainty over the functional significance of these displays. In this study, we explored the efficacy of displays by the lightly banded but non‐mimicking Mexican fruit fly (Anastrepha ludens) in deterring attacks by the salticids Paraphidippus aurantius and Phidippus bidentatus. We tested the effect of band visibility and the fly's physiological condition on the production of these displays and the probability of attack by salticids. We filmed the interactions of flies and spiders and analysed fly displays in the presence of the salticid. We show that the fly's display deters salticids and promotes the fly's chances of survival and that the presence or absence of bands does not alter the possibility of attack. Flies fed on different quality diets showed similar rates of display. Our results suggest that tephritid flies deter attacks because of their display and not their appearance.     

Evolutionary character changes and population responses in an insect host-parasitoid experimental system

In an insect host (the cowpea weevilCallosobruchus maculatus)- parasitoidHeterospilus prosopidis) experimental system, the population densities of the component species oscillated for the first 20 generations and then abruptly stabilized as the parasitoid density decreased. Examination of the host and parasitoid after the 40th generation in the long-term experiment showed that (1) host larvae exhibited contest-type competition (killing other larvae inhabiting the same bean), in contrast to the founder population being scramble-type competitors and (2) the parasitoid attack rate on the host did not change. There was also an evolutionary trade-off between body size and the rates of larval survival and development, suggesting a cost of contest competition on larval survivorship and development. I tested model predictions (Tuda and Iwasa 1998) that (1) host equilibrium population size should gradually decrease as the proportion of the contest type increases and that (2) random attacks of the parasitoid on the host should reduce the rate of increase in proportion of the contest type, and the effect should become manifest especially during the first 20 generations. Two of three host-only replicates showed significant decrease in population sizes. Although the density of emerging adults per bean did not differ between replicates of the host-only and host-parasitoid systems, comparison of the host body size between them on day 270 (at the 13th generation) showed that the host was more contest-type in the host-only system than in the host-parasitoid system, as the model predicted, and later on day 650 the effect of the parasitoid had disappeared.     

Discrimination of different generations of Zeugodacus scutellata using age grading technique and their local genetic variation

The striped fruit fly, Zeugodacus scutellata, exhibits generation overlap due to its relatively long lifespan. This study clarified the fly generations by age-grading technique and traced migration of local populations using genetic markers. Male adults were monitored using Cue-lure in two different places (Andong and Guri) of mainland Korea during the entire host cultivating period. They showed two occurrence peaks (from late July to early August and from mid-August to mid-October). A developmental model of Z. scutellata using rate summation method predicted four generations during this period. Pterin amounts in fly heads increased with adult age and indicated at least 3 cycles of age variation during the occurrence period with an additional adult generation after the third cycle. The additional peak was supported by field monitoring using protein diet supplemented with terpinyl acetate, which showed an additional occurrence peak during October. These seasonal populations were monitored through their migration by gene flow analysis using randomly amplified polymorphic DNA (RAPD) markers. In each locality, three seasonal populations at July, August, and September were discrete. Although local populations were genetically discrete at July, they were not separate at late seasons except for Jeju populations. These results indicate the usefulness of the head pterin quantification in age-grading of adult populations and suggest that Z. scutellata occurs at least four generations a year. In addition, gene flow analysis using RAPD suggests frequent movements among local populations along with season progression.     

绢粉蝶和朱蛱蝶在新疆危害林木的初步观察

报道了绢粉蝶Aporiacrataegi(L .)和朱蛱蝶NymphalisxanthomelasDenisetSchiffer在新疆危害林木的情况。绢粉蝶在阿尔泰山 1年 1代 ,以 2～ 3龄幼虫在叶巢内越冬 ,主要危害疣枝桦 (Betulapendula)和欧洲山杨 (Populustremula) ;朱蛱蝶在天山南麓 1年 2代 ,以成虫越冬 ,主要危害榆树 (Ulmuslaevis)。     

柑桔潜叶蛾自然种群动态及防治策略的研究

从1980年至1985年,在广州市郊的柑桔园研究了柑桔潜叶蛾[Phyllocnistis citrella(Staint.)]自然种群生命表.用Manly的关键因子分析法对五个同次世代的生命表材料进行分析,结果表明,影响关键世代种群变动的关键因子是一龄幼虫自然死亡和二龄幼虫捕食.各发育阶段的天敌因子对关键世代种群变动的影响力达64.6%.据此制定了保护天敌的防治策略,经实践证明,采用此措施可推迟下一代峰期的出现时间,有利于柑桔秋梢在最合适的时间抽放.     

Observations on the biology and ecology of the chrysomelid beetle Gastrophysa polygoni in cereal fields

Abstract. 1. Observations were made on the biology of Gastrophysu polygoni (L.) (Coleoptera: Chrysomelidae) in cereal fields in southern England in 1977, 1978 and 1979. Adults of the overwintering generation emerged in late April/ May and there were usually two generations during the spring and summer months. In 1979 there was some evidence for at least a partial third generation.
2. In the field, the oviposition period was 44 days in the first generation and c . 25 days in the second. Fecundity varied from 586 to 1028 eggs per female and was higher in the first than in the second generation in both 1977 and 1979; in 1978 the reverse was true.
3. Every year there were Iarge losses in the numbers within a generation. However, only one parasite was bred from the developmental stages and a pathogen attacking the larvae was found only in 1977.
4. In some fields and in some years, harvesting and straw burning operations were carried out when eggs were present on the plants. Harvesting did not result in a significant reduction in the numbers of eggs. Burning reduced the numbers of egg batches. The effect was most severe when the straw was spread over the field prior to burning.
5. In the field, significantly more eggs were laid on plants of Polygonum aviculare than on P.convolvulus . In the laboratory, larval survival was higher and duration of development shorter on these two species than on other Polygonaceae found on the farm.     

Oviposition Preferences of the African Wild Silkmoth, <Emphasis Type="BoldItalic">Gonometa postica</Emphasis> Walker (Lepidoptera: Lasiocampidae) on Different Substrates

Gonometa postica Walker (Lepidoptera: Lasiocampidae) is currently being utilised for commercial wild silk production in Eastern Kenya. The oviposition preferences of female G. postica on four substrates in a net-sleeved cage was studied in the laboratory in the long and short rainy seasons in 2007 for two generations, i.e. early (late March to April) and late flights (late September to October) of the moth. The first generation moths laid the highest number of eggs on net sleeves followed by plastic pot, twigs and wooden plank, whereas the second generation moths preferred wooden plank and net sleeves over the plastic pot and twigs. The mean number of eggs, egg clusters laid and percentage egg viability were significantly higher, and the oviposition period was longer for the first than the second generation moths. The mean weight of cocoons was significantly heavier for the first than the second generation. A highly significant positive linear relationship existed between the total number of eggs laid and the cocoon weight. The slopes of the two regression lines for the number of eggs laid against the weight of cocoons were significantly different between the two generations. This information serves to optimise the production of eggs in net sleeved cages in an indoor environment for the semi-captive rearing of the larvae.