SOIL SAMPLING FOR WHEAT-BLOSSOM MIDGES

A method of assessing the population of wheat-blossom midges by the recovery of the cocoons from soil is described.
In the dry summer of 1947, considerable numbers of larvae of Sitodiplosis mosellana Géhin were still in the ears at the time of harvesting. Burning the straw immediately after combining may considerably reduce the numbers of midges.
The majority of the larvae are found in the top 3 in. of the soil although a considerable number may be found from 3 to 6 in. Headland infestations may be lighter than the rest of the field.
Cocoons of S. mosellana remain viable in the soil for several years, and 150,000 per acre were recovered in February 1951 from a field which had not had a wheat crop since 1944. At the same time 50,000 Contarinia tritici Kirby cocoons per acre were found in a field which was last under wheat in 1947.
Viable pupae were successfully obtained by soil sampling, and the pupation in the soil and subsequent emergence of the midges can be followed. Thus it is possible also to estimate the numbers of midges that will emerge.
Progress has been made towards predicting outbreaks of these two midges.     

STUDIES OF FLUCTUATIONS IN INSECT POPULATIONS XII. FURTHER EVIDENCE OF PROLONGED LARVAL LIFE IN THE WHEAT-BLOSSOM MIDGES

Contarinia tritici emerges the same year as the larvae are in the wheat ears and up to 3 years later. Its parasites emerge up to 2 years after the larvae are in the wheat ears, but never the same year. This indicates that the supernumerary generation of C. tritici that occurs on couch grass in August and September may be expected to be free from parasites and so constitutes a dangerous source of replenishment of the pest.
Emergence of Sitodiplosis mosellana can take place after the larvae have been in the soil up to twelve winters. Most of any one year's larvae do not necessarily emerge as midges after one winter, although usually this is so. Any one year's flight is probably a composite one derived from several previous generations of this one-generation-a-year gall midge.     

耕作方式对麦红吸浆虫种群动态的影响

为了解不同耕作方式对麦红吸浆虫Sitodiplosis mosellana （Géhin）种群动态的影响, 2010年和2011年, 在中国科学院河北省栾城农业生态系统试验站不同耕作方式的小麦样地中, 通过淘土、 成虫网捕和剥穗等方法对麦红吸浆虫进行了调查研究。结果表明： 两年取土筛检出的幼虫数量依次为秸秆还田免耕田>秸秆站立免耕田>秸秆还田旋耕田, 但2011年网捕调查显示, 秸秆还田旋耕田中的成虫数量高于另外两种样地。两年剥穗检查出的幼虫数量的排序与取土筛检出的幼虫数量的排序相反, 依次为秸秆还田旋耕田>秸秆站立免耕田>秸秆还田免耕田。分析表明免耕有利于幼虫的越冬, 但免耕田麦穗受害较轻。旋耕对幼虫越冬不利, 但抽穗后受害较严重。在耕种方式是旋耕的情况下, 漫灌可加重吸浆虫的危害。研究结果有助于进一步了解大范围耕作方式的变迁对麦红吸浆虫发生的影响。     

OBSERVATIONS AND EXPERIMENTS ON THE HESSIAN FLY (MAYETIOLA DESTRUCTOR SAY)

Experiments showed that a stem midge collected locally on couch grass ( Agropyron repens ) and similar midges collected on wheat, barley and rye were of the same species, i. e. the hessian fly, Mayetiola destructor Say. There were three main flights per year, with some overlapping of the generations. In experiments, Aegilops ovata, Triticum compactum, T. dicoccoides, T. durum, T. spelta and T. turgidum were successfully used as host plants besides wheat, barley, rye and couch grass. Individual female midges when moved from plant to plant gave rise to families on the different host plants; similarly, succeeding generations of midges were able to breed on various host plants other than those from which they themselves were reared. Oviposition also took place on plants on which larvae failed to establish themselves.
Wheat seemed more favourable for the hessian fly than couch grass, and more midges were reared from young plants than from mature ones.
Unisexual families occurred in about half the experiments. The following parasites were bred: Trichacis didas Walker, Eupteromalus? hemipterus Walker, Platygaster sp., Chrysocharis sp. and Tetrastichus sp.     

CHANGES OF FATTY ACIDS IN LARVAE OF THE WHEAT BLOSSOM MIDGE,SITODIPLOSIS MOSELLANA (GEHIN) (DIPTERA: CECIDOMYIIDAE)*

Abstract The changes of fatty acids in larvae of the wheat blossom midge, Sitodiplosis mosellana (Gehin) at different periods were examined by gas choromatography. There were 10–16 kinds of fatty acids, of which the predominant ingredients were palmitic (C_16:0), oleic (C_18:1) and linoleic (C_18:2) acids which were more than 95% in total fatty acids, stearic acid (C_18:0) about 2%‐3.5% and any of the others was less than 1%. The fatty acid compositions increased from mid‐May, when larvae of the wheat blossom midge left the wheat‐ears and fallen on the ground, to April of next year before pupating and emerging. No arachidic acid (C_20.0) was discovered in over‐summering, over‐wintering as well as inactive over‐wintered larvae. The content of saturated fatty acids in over‐summering, overwintering as well as inactive over‐wintered larvae were less than those of in active over‐wintered larvae and wheat‐ear larvae. Therefore, changes of the arachidic acid and the proportions of saturated fatty acids/unsaturated fatty acids could be used as one of the biochemical criteria to determine the active state and the degree of diapause in larvae of the wheat blossom midge.     

七种杀虫剂对小麦吸浆虫和麦蚜防治效果研究

【目的】明确25%吡蚜酮SC、3%甲氨基阿维菌素苯甲酸盐ME、25%噻虫嗪WG、14%氯虫·高氯氟ZC、15%高氯·毒死蜱EC、2.5%高效氯氟氰菊酯EW和40%毒死蜱EC 7种杀虫剂对小麦吸浆虫和蚜虫的防治效果,为科学、合理用药防治小麦害虫提供参考。【方法】采用喷雾法和剥穗调查法,研究它们对小麦吸浆虫成虫和麦蚜的防效,及防后对小麦吸浆虫幼虫危害损失的影响。【结果】参试药剂药后1 d对小麦吸浆虫成虫防效均高于90%,药后3~5 d防效为84.81%~93.93%,防后挽回损失76%以上;对麦蚜药后1、3、5 d防效分别高于75%、80%和85%。在供试的7种药剂中,15%高氯·毒死蜱EC药后3~5 d对两种害虫防效、挽回吸浆虫危害均超过90%,应用效果最好;其次为25%噻虫嗪WG和40%毒死蜱EC,药后3~5 d对吸浆虫防效高于90%、对麦蚜防效分别高于86%和90%,挽回吸浆虫危害损失88%以上。【结论】供试药剂对小麦吸浆虫和麦蚜防效存在显著差异,15%高氯·毒死蜱EC对两种害虫防治效果最好。     

不同抗性小麦品种上麦红吸浆虫幼虫的空间分布型与理论抽样数

【目的】为了解小麦品种抗性对麦红吸浆虫Sitodiplosis mosellana(Géhin)幼虫在麦穗上空间分布型的影响,为科学调查提供合理的抽样依据。【方法】2015年5月采用剥穗调查法对陕西省周至县试验田种植的4个抗虫和4个感虫小麦品种麦红吸浆虫幼虫危害进行调查,应用6种聚集度指标和Iwao M*?m回归法综合分析了幼虫在抗性不同小麦品种上的的空间分布结构。【结果】幼虫在抗、感小麦品种整穗及麦穗上、中、下部位上空间分布型一致,均呈聚集分布,但在抗虫品种上聚集强度大于感虫品种;抗、感小麦品种上分布的基本成分均为个体群,个体间相互吸引。聚集均数λ分析表明,幼虫在抗性较强品种上的聚集主要由小麦穗部化学物质和形态结构等环境因素引起,感虫品种上则由环境因素和成虫的产卵习性共同作用所致。幼虫在抗、感小麦品种上的发生趋势一致,均是上部发生最重,中部次之,下部最轻。根据Iwao回归法中的分布型参数,确立了幼虫在不同虫口密度和允许误差条件下的理论抽样数。【结论】麦红吸浆虫幼虫在抗性不同小麦品种上均呈聚集分布,调查时应根据当地栽培品种平均虫口密度选择适宜的抽样数量。     

小麦吸浆虫滞育研究进展

小麦吸浆虫Sitodiplosismosellana(Gehin)和Contariniatritici(Kirby)是小麦生产中间歇性猖獗发生的害虫 ,也是一种具有典型的滞育多态性的昆虫。该文从滞育特点、影响滞育的因素、滞育幼虫的形态变化、滞育生理特征、滞育幼虫的化学物质变化和我国小麦吸浆虫滞育区划等 6个方面 ,较全面地回顾总结了国内外小麦吸浆虫滞育研究的进展情况 ,并对今后的研究工作进行了展望。     

一种改进的小麦吸浆虫淘土调查方法及其效果

在多年调查实践的基础上,提出了一种改进的小麦吸浆虫Sitodiplosismosettana(Gelin)淘土调查方法——袋筛箩瓷盘法,并通过试验比较了该方法与传统的箩筛法和近年提出的袋筛箩盐水法的淘捡效果。结果表明,袋筛箩瓷盘法淘捡幼虫多,时间花费少。袋筛箩瓷盘法与袋筛箩盐水法比较,两者的捡虫效果相当,袋筛箩瓷盘法花费时间略少,但不需用食盐调节水的比重,减少了经济支出;与箩筛法比较,箩筛法的捡虫效果仅是袋筛箩瓷盘法的83%,且花费时间比后者多1倍。建议在生产上及时大范围推广袋筛箩瓷盘法淘捡小麦吸浆虫技术。     

Effect of temperature and relative humidity on the cellular defense response of Ephestia kuehniella larvae fed Bacillus thuringiensis

While maintained under all combinations of three temperatures and two RH, fifth instar larvae of the Mediterranean flour moth, Ephestia kuehniella were fed wheat treated with spores and crystals of Bacillus thuringiensis var. kurstaki. Larvae that had fed on wheat with the bacterial preparation contained higher concentrations of nodules in their haemocoel than did larvae fed on wheat without bacteria. Nodule concentrations in larvae fed untreated wheat were unaffected by temperature or relative humidity. Larvae fed treated wheat had higher nodule concentrations at 32 degrees C than at 15 and 23 degrees C, and higher nodule concentrations at a relative humidity of 85% than at 43%. The percentage of larvae that pupated was lower when larvae were fed the bacterial preparation, and was significantly higher at 23 degrees C than at 15 and 32 degrees C, regardless of whether larvae were fed bacteria or not. Less time was required for larvae to develop to pupation at higher temperatures and at higher humidity. Mean time to pupation was lower for bacteria-fed larvae than for those fed untreated wheat, and this appeared to be a result of truncation of the distribution of times to pupation because only rapidly developing larvae survived to pupation.     

Characterization of a serine carboxypeptidase in the salivary glands and fat body of the orange wheat blossom midge, Sitodiplosis mosellana (Diptera: Cecidomyiidae)

A full-length cDNA encoding a serine carboxypeptidase (designated SmSCP-1) was recovered from an ongoing salivary gland EST project of the wheat midge. The deduced 461-amino acid sequence had a putative signal sequence at the amino terminus, indicating it was a secreted protein. The protein shared homology with serine carboxypeptidases from other insects, mammals, plants, and yeasts. SmSCP-1 mRNA was expressed in all stages of development and detected in salivary gland and fat body tissues but not in midgut tissue. Expression analysis and quantitative real-time PCR assays in male and female wheat midges and the fat body tissue of adult midges revealed that SmSCP-1 was up-regulated nearly four-fold in the female midges compared to males and nearly two-fold in female fat body compared to male fat body. The wheat midge serine carboxypeptidase (SmSCP-1) most likely has a dual function. As a secreted digestive enzyme, it could play a role in mobilizing host-plant seed reserves for feeding larvae and as expressed in fat body could function as an exopeptidase in degradation of vitellogenin and/or in post-translational processing of other enzymes.     

致乏库蚊幼虫摄食和消化鱼腥藻的观察(英文)

在实验室条件下,致乏库蚊幼虫可大量摄食鱼腥藻,并能消化利用,完成生活史。鱼腥藻在蚊幼虫肠道中滞 留时间约6h,酵母约5h,鱼腥藻比酵母稍难消化。蚊幼虫至化蛹时期相比,饲喂鱼腥藻为194h,而饲喂酵母的为 142h,饲喂鱼腥藻比饲喂酵母延缓了蚊幼虫期52h。       

EXPERIMENTS ON THE MODE OF ACTION OF DIELDRIN SEED-DRESSINGS AGAINST SEEDLING ATTACK BY THE LARVAL FRIT FLY, OSCINELLA FRIT L

Experiments with dieldrin seed-dressings were done to see whether the conditions favouring their action against wheat bulb fly larvae apply also to frit fly.
Experiments with oats and wheat in boxes and a small field trial with oats showed that fewer newly hatched larvae were killed when dieldrin-treated seed was sown deeply than when sown 1/4 - 1/2 in. deep; shallow sowing probably puts the insecticide where the larvae are likely to meet it before they attack the plant. Kill was never complete even with dieldrin applied at almost forty times more than the highest rate normally used. This is partly because some larvae hatch from eggs on the plant and these, unlike those from soil eggs, can enter the shoot without touching the seed dressing.
Even in the most favourable circumstances (large doses of dieldrin applied to the shallow-sown seed and the plant at the one-leaf stage at the time of attack) there was little evidence that frit fly larvae are killed inside the shoot by systemic action of dieldrin translocated from the seed. This is not because the pales which normally surround the oat seed impair the uptake of insecticide, or because of any other factor specific to oats. Frit fly larvae also survived in wheat from seed dressed with doses of dieldrin that can kill almost all wheat bulb fly larvae by systemic action. Possible reasons for this difference are discussed.     

Hessian fly-associated bacteria: transmission, essentiality, and composition

Plant-feeding insects have been recently found to use microbes to manipulate host plant physiology and morphology. Gall midges are one of the largest groups of insects that manipulate host plants extensively. Hessian fly (HF, Mayetiola destructor) is an important pest of wheat and a model system for studying gall midges. To examine the role of bacteria in parasitism, a systematic analysis of bacteria associated with HF was performed for the first time. Diverse bacteria were found in different developmental HF stages. Fluorescent in situ hybridization detected a bacteriocyte-like structure in developing eggs. Bacterial DNA was also detected in eggs by PCR using primers targeted to different bacterial groups. These results indicated that HF hosted different types of bacteria that were maternally transmitted to the next generation. Eliminating bacteria from the insect with antibiotics resulted in high mortality of HF larvae, indicating that symbiotic bacteria are essential for the insect to survive on wheat seedlings. A preliminary survey identified various types of bacteria associated with different HF stages, including the genera Enterobacter, Pantoea, Stenotrophomonas, Pseudomonas, Bacillus, Ochrobactrum, Acinetobacter, Alcaligenes, Nitrosomonas, Arcanobacterium, Microbacterium, Paenibacillus, and Klebsiella. Similar bacteria were also found specifically in HF-infested susceptible wheat, suggesting that HF larvae had either transmitted bacteria into plant tissue or brought secondary infection of bacteria to the wheat host. The bacteria associated with wheat seedlings may play an essential role in the wheat-HF interaction.     

THE EFFECT OF DATE OF SOWING ON THE INCIDENCE OF POWDERY MILDEW ON SPRING-SOWN CEREALS

Delaying the date of sowing of spring-sown barley in 1953 and wheat in 1954 from February to April increased the incidence of powdery mildew, Erysiphe graminis DC., from May onwards. Before then, conditions did not favour the rapid spread of mildew.
From mid-June, infected barley produced necrotic lesions. These developed sooner on the early- than on the late-sown crops, and on the lower than upper leaves. Perithecia were first seen on 29 June. They were abundant on the wheat by 20 July.
Mildew reduced the yield of barley sown on 30 March and 28 April 1955 by 8 cwt./acre. The percentage loss was greater in the late- than in the early-sown crops. The number of ears per metre of row, the weight of 100 ears and the 1000-grain weights were reduced. Altering the seed rate from 1 ½ to 2½ bushels/acre did not affect the incidence, or the effect, of mildew on grain yield.     

不同饵料对稀有鳇鲫仔稚鱼生长、消化道及消化酶的影响

为了筛选稀有逗鲫(Gobiocypris rarus)仔稚鱼期合适的饵料, 将初孵仔鱼随机分为3个组: 活饵组、饲料组、转食组, 每组3个平行, 均从3 dah(day after hatching)开始投喂相应饵料, 在10、15、20、25、30、35 dah时统计生长指标和存活率, 并进行35 dah仔稚鱼消化道组织学及消化酶活性研究。结果显示: (1)35 dah时, 活饵组存活率最高; (2)从15 dah开始, 活饵组表现出最好的生长性能, 并维持这种趋势; (3)活饵组的消化道各部肌层厚度、黏液细胞数目均最高, 提示该组仔稚鱼消化道发育状态较好, 并具有较优的消化吸收能力; (4)转食组胰蛋白酶活性显著高于活饵组和饲料组。研究结果提示: 相对于饲料和转食, 一直投喂活饵更有利于稀有逗鲫仔稚鱼的生长和发育。建议在标准化养殖过程中, 对仔稚鱼期的稀有逗鲫采取活饵投喂的方式。     

大菜粉蝶颗粒体病毒对菜粉蝶幼虫取食、生长、发育的影响

菜粉蝶幼虫在一、二、三、四龄初期饲以大菜粉蝶颗粒体病毒(PbGV),食量减少99.3—38.4%;四龄末或五龄初饲毒,食量反而比健虫高出36.3%和87.2%。幼虫感病后取食期的缩短或延长是食量变化的主要原因。幼虫病死前脱皮过程先被抑制,其结果往往使得死亡时所处的龄期明显延长。幼虫在四龄末饲毒后,由于五龄期延长,食量增加,其死亡前达到的最高体重平均为357.9毫克,远高于健虫化蛹前的最高体重。PbGV对菜粉蝶化蛹也有明显影响。幼虫在五龄前饲毒,一般不能化蛹。五龄第1—3天饲毒,化蛹率26.4—87.9%,第4天饲毒对化蛹无影响。本文结果对应用PbGv防治菜粉蝶幼虫危害以及对该病毒的大量增殖均具指导意义。     

Larval diet influence on oviposition behaviour inSpodoptera littoralis

Females ofSpodoptera littoralis Boisd. (Lepidoptera: Noctuidae) with different feeding experiences during their larval development were tested for their ovipositional response to methanol extracts of larval frass and semisynthetic diets. The effect of the following frass, diet and diet component extracts was tested: (a) frass fromS. littoralis orAgrotis segetum larvae fed on a potato-based diet; (b) frass fromS. littoralis larvae fed on a wheat germ-based diet; (c) potato and wheat germ-based diets; and (d) potatoes and wheat germ. Ovipositing females without prior experience of the potato diet were deterred by extracts of: (1) larval frass from either species fed on potato diet; (2) the potato-based diet; (3) potato. Also females with experience of the potato diet during only a part of their larval development were deterred from oviposition by frass of larvae reared on the potato diet and by the diet itself. However, for females reared on the potato diet for their entire larval development, oviposition was no longer deterred by either of the three extracts listed above. Extracts of: (1) frass from larvae of either species reared on wheat germ diet: (2) the wheat germ diet; or (3) wheat germ did not significantly affect oviposition. Females with ablated antennae were still deterred by frass extracts from larvae fed on potato diet, when they had been reared on the wheat germ diet. In feeding experiments, larvae of larval stage one and of larval stage three-four reared on either of the two diets preferred to feed on the wheat germ diet. However, the preference was significantly stronger for larvae with no prior contact with the potato diet. The effect of larval experience on the loss of oviposition-deterring activity by extracts of larval frass, diets and diet components is discussed in view of induction and selection.     

烟青虫人工饲料的研究

本文报道烟青虫Heliothis assulta的一种人工饲料,其主要成分是麦胚、酵母粉、番茄酱和辣椒粉.与自然食料相比,用这种人工饲料饲养的烟青虫生长快、发育整齐、存活率高,得到的蛹大,成虫繁殖力强.饲料中含0.1—0.2%的NaCI对幼虫的生长发育有促进作用.6龄幼虫对该饲料中干物质、能量和氮的同化效率分别是38.5%、43.9%和48.5%.在连续12代饲养期间,幼虫期存活率在57—92%之间,平均76%.     

小麦吸浆虫滞育幼虫甘油含量的季节变化(英文)

采用比色分析方法测定了小麦吸浆虫Sitodiplosis mosellana滞育期间幼虫甘油含量的季节变化。结果表明,幼虫离穗入土以前,甘油含量很低,仅为2.96±1.19μg/mg。幼虫离穗入土后,甘油含量急剧升高。入土后5d,甘油含量即上升为6.58±1.11μg/mg;至入土后17d,甘油含量达到高峰,12.21±2.21μg/mg。以后随时间的短期变化其含量变化不大,但随季节变化表现了一定的规律性,呈现了上升——下降——再上升——再下降的变化趋势,即夏季和冬季含量较高,秋季和春季含量较低。结茧幼虫和裸露幼虫比较,结茧幼虫的甘油含量在盛夏和冬季略高于裸露幼虫,秋季和春季时二者含量相当,两者在统计学上并无显著的差异。同一季节的当年滞育幼虫和进入第2年滞育幼虫的甘油含量无明显差异。由此可见,小麦吸浆虫幼虫滞育期间,甘油含量受季节或滞育深度的影响较大。