二化螟水稻种群与茭白种群光周期反应的比较

本文报道了用水稻和茭白分别饲养二化螟水稻种群和茭白种群的光周期反应。光周期反应曲线显示,用水稻饲养茭白种群或用茭白饲养水稻种群,无论是在短光照还是在长光照条件下,绝大多数幼虫被诱导进入滞育,丧失了各自原有的光周期反应特性,表明这两个种群已分化到仅适应其本身寄主的程度。用水稻饲养的茭白种群仅有5%～6%的个体化蛹,且其幼虫期较用茭白饲养的延长了15～18天;而用茭白饲养的水稻种群有30%～40%的个体化蛹,其幼虫期与水稻饲养的仅相差3～8天。茭白种群用水稻饲养时32日龄幼虫体重仅为茭白饲养的53.1%,而水稻种群用水稻饲养时32日龄幼虫体重为茭白饲养的79.5%。这些结果表明,茭白种群不适应取食水稻,而水稻种群对取食茭白则有一定的适应能力。根据这些结果,我们认为：（1）这两个种群已出现种下分化的迹象;（2）茭白种植不会对水稻田二化螟的发生产生大的影响。     

地下围栏对马铃薯田甘肃鼢鼠的防治效果研究

甘肃鼢鼠是一种广泛分布于黄土高原地区的地下害鼠,无冬眠和夏眠现象,食性广泛,但其活动取食范围相对比较固定,本文针对被广泛应用于农田地上害鼠防控的TBS系统原理,在甘肃鼢鼠防治中的探索研究围栏防治效果及可行性.结果表明各围栏均能减少处理区甘肃鼢鼠对马铃薯的为害,提高马铃薯产量,封闭式竹条地下围栏对甘肃鼢鼠具有较好的阻截作用,能够完全阻截甘肃鼢鼠迁入处理区取食为害,但金属网地下围栏不能完全阻截甘肃鼢鼠迁入为害.封闭式竹条地下围栏处理区甘肃鼢鼠未迁入为害,为害率为0%;带诱捕孔的开放式金属网地下围栏处理区平均受害面积1.8m²,为害率达7.2%,但诱捕孔不能诱捕甘肃鼢鼠;开放式金属网地下围栏处理区平均受害面积2.47 m²,为害率达9.87%.三者对马铃薯增产分别达33.06%, 28.54%和19.73%.本研究为探索围栏系统对甘肃鼢鼠的防控提供了非常高的指导意义.     

利用茭白、荸荠及水稻饲养二化螟的技术研究

分别用水稻苗、茭白、水稻 +荸荠 3种方法 ,喂饲二化螟Chilosupperssalis初孵幼虫 ,比较室内 3种饲养方法对二化螟生长发育和繁殖力的影响 ,从而为二化螟的实验室饲养提供方法和依据。其中 ,在整个幼虫期用茭白饲养的二化螟幼虫发育历期和化蛹历期最短 ,分别为 ( 1 7 8± 0 5 )d和 ( 9 8± 0 8)d ,而用水稻苗饲养的二化螟幼虫发育历期和化蛹历期最长 ,分别为 ( 3 0 4± 1 2 )d和 ( 2 0 0± 1 6)d。水稻苗喂饲二化螟的雌雄蛹的比例较低 ,仅为 0 44;荸荠有利于雌性个体的分化 ,用水稻 +荸荠相结合喂饲二化螟的雌雄蛹比例为 1 1 8。用荸荠喂饲的蛹最重 (雌和雄蛹重分别为 71和 5 1mg 头 )。 3种饲养方法对二化螟的产卵率和孵化率无显著影响 ,但是 ,用水稻饲养二化螟蛹的羽化率比其它 2种饲养方法显著降低。由此可见 ,用茭白、水稻苗 +荸荠饲养方法进行二化螟饲养是切实可行的 ,它们有利于二化螟的生长发育。     

曲纹紫灰蝶的生物学特性和发生动态研究

近年来 ,曲纹紫灰蝶Chiladespandava在广东省苏铁上大量发生 ,一些苏铁园 ,苏铁的受害株率为 2 0 %～ 3 0 % ,有的高达 5 0 %～ 60 %。调查研究了曲纹紫灰蝶的生物学特性及种群发生动态 ,结果如下。 ( 1 )幼虫分 4龄。据广州 9～ 1 0月的观察 ,卵的平均历期为 ( 1 5 2± 0 1 1 )d ,幼虫期为 ( 5 96± 0 1 9)d,蛹期为 ( 5 1 4± 0 3 8)d。成虫卵散产于苏铁嫩芽上。幼虫危害苏铁嫩芯 ,严重时苏铁的叶片、叶柄全部被吃光。 ( 2 )成虫在上午 9:3 0～ 1 0 :3 0活动数量最多。 ( 3 )曲纹紫灰蝶全年都能发生。成虫、卵、幼虫、蛹分别在 5月和 1 0月出现发生高峰 ,前峰高于后峰。其发生高峰期与苏铁的抽芯盛期相吻合。 ( 4 )防治策略 :合理采取措施压基数 ,综合防治控为害 ,即全年曲纹紫灰蝶防治的关键是掌握每年苏铁的第 1个抽芯高峰期 ,采取合理措施 ,压低曲纹紫灰蝶数量 ,持续监控发生动态 ,在第 2个发生高峰的卵孵化盛期用药防治。     

大豆毒蛾为害茭白

<正> 在江苏连云港地区大豆毒蛾Cifuna locu-ples Walker严重为害茭白Zizania caducif-lora。该虫在当地一年发生3代,以幼虫越冬,次年3月中下旬开始取食茭白距水面10cm以上的叶片。据调查每单株茭白有虫8～10头,被害率高达87.5％以上,其中生长密度较大的     

稻苞虫猖獗为害茭白

9月中旬,在临川县鹏溪的二季晚稻田中间,有一坵约3分田的茭白Zizania latifolia H.,遭受到稻苞虫Parnara guttata B.G.严重为害。据调查,百叶有虫苞达80—100个,被害后叶片仅留中肋和叶绿。而旁边生长青绿正处于圆稈——孕穗期的二季晚稻,每百丛禾却只有虫苞4—7个。据报导,菱白是稻苞虫的越冬寄主之一,在食料缺乏的情况下才为害茭白,而此次稻苞虫猖獗为害茭白,却是少见。     

重庆市秀山县稻飞虱发生特点及其原因分析

重庆市秀山地区稻飞虱的发生主害种类为白背飞虱Sogatellafurcifera和褐飞虱Nilaparvatalugens,白背飞虱的危害重于褐飞虱 ;白背飞虱 1年发生 5～ 6代 ,以 4 ( 3)代为主害代 ,田间发生 2～ 3次若虫高峰 ,以第 2次为主害代峰、虫量最大 ;褐飞虱 1年发生 4～ 5代 ,以 5 ( 4 )代为主害代 ,田间发生 3～ 4次若虫高峰 ,以第 3次为主害代峰、虫量最大 ;( 3)稻飞虱重发年比例高 ,达 85 %以上 ;( 4 )白背飞虱呈逐年加重和主害期提前、褐飞虱呈逐年减轻和主害期推迟的趋势。其主要原因是 :特殊的槽谷地形、迁入虫量大、品种及栽培技术的变化、防治技术的提高和气候条件有利等。     

甘蔗斑点象生物学及防治的研究

甘蔗斑点象是云南甘蔗上另一种新的严重蛀食地下蔗头的害虫,主要以幼虫在甘蔗地下蔗头内为害,为害期8～9个月,受害蔗每666．7m2减少0．5～0．3t,并缩短了宿根年限。此虫1年发生1代,无越冬现象,有喜湿性,不能飞翔,主要通过沟河流水传播。在河川坝地、沙壤地中虫口较多,宿根年限越长受害越重。蔗稻轮作,缩短宿根年限翻蔸烧蔸,结合松蔸培土每666．7m2用3％米乐尔或3％甲基异柳磷颗粒剂4kg,防治效果达90％左右。     

葱斑潜蝇防治指标及防治适期研究

研究表明葱斑潜蝇百株潜道 (X)与大葱产量损失率 (Y)之间呈显著的相关性 ,其相关回归式 :Y=-2 .8397+ 0 .0 30 4 8X。在大葱产量 30 0 0～ 6 0 0 0kg 6 6 7m2 时 ,经济允许损失率为 1 .4 7%～ 2 .94 % ,允许百株潜道为 1 4 1 .4～ 1 89.6条 ;防治指标拟定为百株潜道 1 5 0条。防治适期为成虫羽化高峰期至幼虫初孵期 ;大葱生育中、后期 ( 6～ 1 0月 )防治对于降低葱属作物的损失具有较大意义。药剂防治以含有阿维菌素的制剂和乐斯本效果较好。     

烟草粉斑螟的观察

烟草粉斑螟是烟叶及卷烟贮存期的重要害虫。本工作研究了烟草粉斑螟的生活史、习性及影响消长的主要因子。在湖北省该虫一年发生2～3代,在26～30℃,相对湿度70～90％对,卵历期5～7天,幼虫期29～50天,幼虫5～6龄,蛹期6～18天。幼虫蚕食烟叶成孔洞,老熟幼虫在烟叶表面或麻袋及仓库隐蔽处吐丝结茧化蛹。烟叶从收购入库至贮存各环节均可遭受为害,以卷烟厂贮存过程受害最甚。通常高、中档烟叶受害重于低挡烟叶,其烟草粉斑螟种群密度随着贮存期的延长呈线性增加。烟叶含水量达13％时,幼虫发育迅速,为害重;含水量低于10％时,幼虫发育受到明显影响。     

胚轴切断法诱导棉株对棉铃虫生长发育的影响

通过室内饲喂棉铃虫的方法,测定了诱导棉株对棉铃虫幼虫发育历期、幼虫体重和肾重的影响。结果表明,不加菌处理和加菌处理的诱导抗性棉株可分别使棉铃虫幼虫发育历期延长０．５和３ｄ,幼虫体重（５龄）降低１１．４５％和１９．６０％,蛹重降低６．５４％和１０．８１％。用诱导棉株叶片饲养８日龄棉铃虫幼虫３天后,菌诱导和无菌诱导分别使棉铃虫的相对生长率降低２２．９％和１７．２％,相对取食量降低２６．１％和２１．４％     

滇青冈和高山栲种子昆虫寄生及其对种群更新的影响

对昆明西山地区滇青冈(Cyclobalanopsis glaucoides)和高山栲(Castanopsis delavayi)种子(坚果)虫蛀率在两个年份、整个落种期和山坡不同部位的变化情况进行研究,结果表明：① 寄生于滇青冈种子内的象甲为青冈象(Curculio megadens)和Curculio sp.,寄生于高山栲种子内的象甲是Curculio sp.和剪枝象(Cyllorhynchites sp.);② 滇青冈样地的虫蛀率为2484%~2760%,样地间无显著差异,两年间的平均虫蛀率亦无显著差异;高山栲样地间虫蛀率为1794%~2655%,有显著差异性,两年间的平均虫蛀率也有显著差异。③ 高山栲的下落种子虫蛀率随时间逐步下降,9月和10月中下旬出现两个虫蛀率的高峰期;高山栲种子内寄生的昆虫落地后即入土化蛹,滇青冈落地种子内的寄生昆虫在初期会滞留一段时间;④ 虫蛀率与林下实生苗数量无显著相关性,实生苗多集中在大树周围以及草本层植物较丰富的小生境。     

水稻穗期大螟危害习性初步观察

于2009年常规中稻的蜡熟前期、中期和黄熟期、枯熟期,分别取样观察大螟Sesamia inferens Walker的钻蛀危害习性。结果发现:单株螟害的蛀孔数一般为2～3个,多的达5个,而且表现白穗株>枯穗株>虫伤株。螟害株的蛀孔部位随着稻穗趋向成熟和大螟虫龄的增大,逐渐由稻株的中上部节间向中下部节间转移。其中,白穗株与枯穗株有70%以上的蛀孔分别分布于稻株由上向下的第1～3与3～5节间上;在水稻的这4个生长时期中,虫伤株有90%左右的蛀孔分别分布于稻株由上向下的第1～3、1～4和2～5、3～5节间上,全株虫量有85%以上依次分布于第1～3、2～4和3～5、3～5节间上,单株虫量4个时期最高分别为18、6、3、2头,同一节间内的4个时期最高虫量分别为12、5、1、1头;单个节间有多头螟虫时,80%以上为1～3龄幼虫。随着稻穗趋向成熟,白穗株和枯穗株上的虫量均逐渐下降,而虫伤株上的虫量则相对稳定或有上升的趋势;至枯熟期后,虫伤株的有虫株率和有虫孔率均稳定在30%以上。     

Preference for plants damaged by conspecific larvae in ovipositing cabbage root flies: influence of stimuli from leaf surface and roots

In laboratory dual-choice assays females of the cabbage root fly, Delia radicum, prefer for oviposition plants with roots damaged by conspecific larvae to undamaged controls. Cauliflower and kale plants were inoculated with root fly eggs (25 per plant) and the hatching larvae were allowed to feed on the roots for various periods of time (1–17 days). After 4 (cauliflower) or 5 (kale) days of larval feeding the oviposition preference was most pronounced and flies laid between 64% and 68% of their eggs near plants with damaged roots. Later, with increasing damage but fewer surviving, and thus actively feeding, larvae, the magnitude of the preference declined. The preference for plants already damaged by conspecific larvae may contribute to the previously observed aggregated distribution of D. radicum eggs in Brassica crop fields.Further experiments revealed that the sensory cues inducing this oviposition preference originate from the complex consisting of the damaged roots, the surrounding substrate (soil) and associated microbes, rather than from the aerial plant parts. In choice assays using the root-substrate complex of damaged and control plants (aerial parts removed), the observed preference for damaged roots was similar to that found for the entire plant but was more pronounced. The damaged roots alone, compared to control roots, received up to 72% (cauliflower) and 75% (kale) of the eggs. By contrast, surrogate leaves sprayed with methanolic leaf surface extracts from the most preferred plants which had been damaged were not discriminated from surrogate leaved sprayed with extracts of the respective control plants. Analysis of glucosinolate levels in methanolic leaf surface extracts revealed that root damage resulted in enhanced concentrations of indole-glucosinolates on the leaf surface in kale but not in cauliflower. Although indole-glucosinolates are oviposition stimulants for the cabbage root fly, the induced changes were apparently too small to influence oviposition behaviour.     

中红侧沟茧蜂对不同龄期棉铃虫幼虫及其为害棉株的趋性反应

研究中红侧沟茧蜂Microplitis mediator Haliday对棉铃虫Helicoverpa armigera Hübner幼虫及其为害棉株的趋性行为, 可为高效应用中红侧沟茧蜂控制棉铃虫提供理论依据。本研究在实验室内以中红侧沟茧蜂雌蜂、1~5龄棉铃虫幼虫及其为害棉花植株（去虫或未去虫）为试验材料, 采用“Y”型昆虫嗅觉仪测定了中红侧沟茧蜂雌蜂对1~5龄棉铃虫幼虫及其为害棉株的趋性行为反应。结果表明: 中红侧沟茧蜂对3龄、4龄和5龄棉铃虫幼虫均没有明显的趋向行为反应, 1龄和2龄棉铃虫幼虫对中红侧沟茧蜂有显著的引诱作用。此外, 1~5龄棉铃虫幼虫为害后去虫棉株与健康棉株均对中红侧沟茧蜂有吸引作用。在未去虫的处理中, 虫害诱导棉株比健康植株更能吸引中红侧沟茧蜂, 与健康植株差异显著, 而且不同龄期棉铃虫幼虫为害处理间差异较大, 对中红侧沟茧蜂引诱作用的相对顺序为: 5龄为害植株>2龄和4龄为害植株>1龄和3龄为害植株 (2龄和4龄为害处理间差异不显著; 1龄和3龄为害处理间差异不显著)。本研究结果可为中红侧沟茧蜂在生物防治上的应用提供一定的理论指导和实践依据。     

Efficacy of Trichogramma wasps for controlling tomato leaf miner Tuta absoluta

Tomato is considered as one of the most essential vegetables after potato in Egypt. Tomato is infested by many insects; one of these serious insects is tomato leaf miner Tuta absoluta, which causes yield losses up to 100%. T absoluta is attacking leaves, flowers, stems and fruits. Trichogramma species is playing an important role in reducing this insect infestation. Efficiency of Trichogramma evanescens alone and in combination with insecticides were assessed against T. absoluta in tomato fields. Three release rates 500, 1000 and 1500 parasitized egg/card as well as 2 insecticides (Dimilin and Corgen) were applied. Number of normal and parasitized eggs, live and dead larvae and tunnel numbers were recorded. The results revealed that T. absoluta eggs were higher in control plots than those counted in Trichogramma plots. Among Trichogramma release rates, higher release rates, obtained higher parasitism rates of Tuta eggs (reached to 50%). Companying Trichogramma with IGR Dimilin had a little side effect on parasitism rate which it was smaller compared to plots of Trichogramma alone. Dimilin (IGR) caused reducing in Tuta larval population, which it differed significantly compared to control plots. Another IGR, Coragen resulted increasing the mortality of Tuta larvae than other treatments. In Trichogramma release rates, higher release rates, lower number of tunnels were found. In plots of companying Trichogramma with Coragen, the lowest tunnel numbers were recorded. Field release of T. evancences would be a promise biocontrol agent to suppress T. absoluta. These findings may encourage using T. evancences as a favorable strategy for integrated management of T. absoluta to produce safe tomato.     

Bollworm responses to release of genetically modified Helicoverpa armigera nucleopolyhedroviruses in cotton

Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HaSNPV) has been developed as a commercial biopesticide to control the cotton bollworm, H. armigera, in China. The major limitation to a broader application of this virus has been the relative long time to incapacitate the target insect. Two HaSNPV recombinants with improved insecticidal properties were released in bollworm-infested cotton. One recombinant (HaCXW1) lacked the ecdysteroid UDP-glucosyltransferase (egt) gene and in another recombinant (HaCXW2), an insect-selective scorpion toxin (AaIT) gene replaced the egt gene. In a cotton field situation H. armigera larvae treated with either HaCXW1 or HaCXW2 were killed faster than larvae in HaSNPV-wt treated plots. Second instar H. armigera larvae, which were collected from HaCXW1 and HaCXW2 treated plots and further reared on artificial diet, showed reduced ST(50) values of 15.3 and 26.3%, respectively, as compared to larvae collected from HaSNPV-wt treated plots. The reduction in consumed leaf area of field collected larvae infected with HaCXW1 and HaCXW2 was approximated 50 and 63%, respectively, as compared to HaSNPV-wt infected larvae at 108 h after treatment. These results suggest that in a cotton field situation the recombinants will be more effective control agents of the cotton bollworm than wild-type HaSNPV.     

Resistance of potatoes transgenic for a cry1Ac9 gene, to Phthorimaea operculella (Lepidoptera: Gelechiidae) over field seasons and between plant organs

Stable performance of insect‐resistant transgenic plants across field seasons and between plant organs damaged by the insect pest is critical for management of this resistance in the field. To evaluate this, potato (Solanum tuberosum) lines transgenic for a cry1Ac9 gene with resistance to potato tuber moth (Phthorimaea operculella) were established in the field during the southern hemisphere summers of 1997/98, 1998/99 and 1999/00 as small field plots, each of 10 plants. Replicate plots of the non‐transgenic parent cultivars (at least one for every three independently derived transgenic lines) were planted randomly throughout the trials. Field‐grown foliage was challenged with larvae in the laboratory and a growth index (GI) was calculated for recovered larvae from each transgenic and non‐transgenic potato line. Larval growth on young and mature leaves, and on newly harvested or stored tubers was also measured in the laboratory. Foliage from the transgenic lines inhibited larval growth in all seasons tested. For both control and transgenic lines, larvae had slightly lower GIs when reared on mature leaves compared with young leaves, although the correlation between mean GI for young and mature transgenic leaves was high (r = 0.97). The correlation between the mean GIs of larvae on newly harvested tubers and on those stored for 5 months was also high (r = 1.0). However, the GIs of larvae on newly harvested transgenic tubers were larger than on transgenic tubers stored for 5 months. The relative growth indices (RGI = mean GI/number days before final weighing) of larvae reared on newly harvested tubers from transgenic lines were generally higher than those from young transgenic foliage, while the RGIs of larvae reared on non‐transgenic tubers were slightly lower than those fed non‐transgenic foliage. The correlation between mean RGIs of larvae fed tubers or foliage was 0.62. The transgenic potato lines exhibited stable resistance to larvae across field seasons, between affected plant organs, and between plant organs of different ages.     

Biological performance of quercetin on the cotton leaf-worm larvae, Spodoptera littoralis Boisd. (Lep., Noctuidae) and prevailing natural enemies in the Egyptian cotton fields

The Egyptian cotton (Gossypium barbadense L.) accounts for 65 % of the world production of long stable cultivars. Taking into consideration the competition of other cotton producing countries, it should be of great importance to control pests, which attack the cotton plants to improve the yield and its quality. The main objective of this study is to develop new approaches for the management of the cotton leafworm Spodoptera littoralis Boisd. within an IPM program, that include synthetic insecticides rationalization, and maximiziation the role of the biological control agents. Sunflower plants Helianthus annuus (Asterales: Asteraceae) raised in rows surrounding plots of cotton were used as trap plants to attract some biological agents, which subsequently lead to check the build-up of the cotton leafworm population. This scientific phenomenon was attributed to the main chemical constituent of sunflower plants, which has been proved to be the polyhydroxy flavone "quercetin". Field data of the two successive seasons 2004 and 2005 revealed that: (a) the total number of insect predators, Coccinella undecimpunctata, Paederus alfierli, Chrysopa vulgaris, Orius laevigatus, Scymnus synacus, and true spiders in the cotton plots surrounded by either one or two rows of sunflower plants significantly exceeded the corresponding numbers in the cotton plots without sunflower plants., (b) the least number of cotton leafworm Spodoptera littorolis larvae infestation was recorded simultaneously in the cotton plots surrounded by sunflower plants. Moreover, laboratory studies assured the antifeeding properties of quercetin against the 4th instar larvae of Spodoptera littoralis. Quercetin at a concentration rate of 4000 ppm, showed abnormal behaviour represented in feeding stop, growth inhibition and development retardation. Deformation of pupae, moths, and reduction up to 50% in egg laying was also noticed after quercetin application to the larvae.