取食不同品种棉花的棉蚜对龟纹瓢虫功能反应的影响

本文以GK12、33B和SGK3213种转基因棉和对应的3种常规棉泗棉3号、33及石远321为材料,通过室内测定,研究了取食转基因棉的棉蚜却h／sgossypiiGlover对龟纹瓢虫Propylaea japonica Thunberg1—4龄幼虫功能反应的影响。结果指出,龟纹瓢虫对来自转基因棉田蚜虫的捕食量大多高于常规棉田,且捕食量随猎物密度的增加而增大。在1、2龄幼虫期,龟纹瓢虫取食转双价基因棉田蚜虫的数量多高于取食转单价基因棉田的蚜虫数量,但是在3、4龄幼虫时,龟纹瓢虫取食转双价棉田蚜虫的数量多低于取食转单价棉田的蚜虫数量。龟纹瓢虫对来自转基因棉田棉蚜的捕食功能反应符合HollingII型。龟纹瓢虫1龄幼虫取食GK12和SGK3212个转基因棉田蚜虫的最大日捕食量大于对照,处理时间短于对照;龟纹瓢虫P．japonica2、3龄幼虫取食33B和SGK3212个转基因棉田蚜虫A．gossypii的日最大捕食量大于对照,处理时间短于对照;4龄时取食转基因棉田蚜虫的数量都大于对照,处理时间均短于对照,其中取食转双价基因棉SGK321棉田蚜虫的日最大捕食量小于取食单伊棉田蚜虫的日最大捕食量。     

转Bt基因棉花中Cry1Ac蛋白经烟粉虱途径向龟纹瓢虫的传递

【目的】烟粉虱Bemisia tabaci是转基因棉的非靶标害虫,对棉花生产造成严重影响。本文探讨转Bt基因棉花中Cry1Ac蛋白在棉花-烟粉虱-龟纹瓢食物链中的传递规律,以期为转基因棉的环境安全评价提供科学依据。【方法】在实验室条件下,以常规棉SM3号、33、SY321为对照,分析转Bt基因棉花GK12、XM33B、SGK321叶片、在这些棉花上取食的烟粉虱、以及捕食烟粉虱的瓢虫体内Cry1Ac蛋白含量。同时,将取食转Bt基因棉花上的烟粉虱的瓢虫转接到对应的受体亲本棉花上,分析瓢虫体内Cry1Ac蛋白含量变化规律。【结果】在转Bt基因棉花上取食的烟粉虱成虫和若虫以及它们的蜜露中均能检测到Cry1Ac蛋白,以转Bt基因棉花上的烟粉虱若虫为食料的龟纹瓢虫体Propylaea japonica内也能检测到Cry1Ac蛋白。龟纹瓢虫取食转Bt基因棉花上的烟粉虱若虫1 d后体内即能检测到Cry1Ac蛋白,并且随着取食时间的延长,体内Cry1Ac蛋白的含量逐渐增加,但到第6~8天后Cry1Ac蛋白的含量相对稳定。取食3个不同品种棉花上烟粉虱若虫的龟纹瓢虫体内Cry1Ac蛋白的含量存在明显差异,这种差异与棉花叶片上表达的Cry1Ac蛋白量呈正相关。但取食后6 d,在3个品种棉花上取食的龟纹瓢虫体内的Cry1Ac蛋白含量之间没有明显的差异。以转Bt基因棉花上的烟粉虱若虫为食料的龟纹瓢虫转移到对应的常规棉亲本上以后,体内的Cry1Ac蛋白的含量迅速下降,但10 d后仍能检测到微量的Cry1Ac蛋白。【结论】转Bt基因棉花中的Cry1Ac蛋白可以通过烟粉虱途径传递到龟纹瓢虫体内,龟纹瓢虫对食料中的Cry1Ac蛋白具有富集作用,并且Cry1Ac蛋白的富集存在饱和现象,富集饱和量与食料中的Cry1Ac含量无关;龟纹瓢虫脱离含有Cry1Ac蛋白的食料环境后,体内的Cry1Ac蛋白可以消减,但在10 d时间内龟纹瓢虫体内仍会有Cry1Ac残留。     

龟纹瓢虫在棉株上对棉蚜的搜索与捕食行为

研究了龟纹瓢虫在棉花上对不同密度、不同空间分布、不同来源棉蚜的搜索与捕食行为.结果表明,龟纹瓢虫对棉蚜的搜索活动随棉蚜密度增加而下降;当棉花上有充足的棉蚜时,瓢虫主要搜索和捕食棉花上部的棉蚜,很少捕食棉花中部的棉蚜,极少捕食下部的棉蚜;瓢虫对棉花不同部位上分布的2种不同来源的棉蚜捕食量没有差异;但当棉花上部主要为美9101棉花棉蚜时,瓢虫的搜索活动明显下降.龟纹瓢虫的捕食行为与蚜虫密度和空间分布密切相关.     

Leaf surface factors of transgenic Bt cotton associated with the feeding behaviors of cotton aphids: A case study on non-target effects

The present paper reports case study results of the risk assessment of transgenic Bt cotton on a non-target pest, cotton aphid, Aphis gossypii. Several types of techniques, i.e., electrical penetration graph (EPG), light and electron microscopy, bioassays and chemical analysis, were applied to investigate physical and chemical leaf factors of 2 transgenic Bt cotton lines (GK12 and GK19) and their pa-rental non-Bt cotton line (Simian3) associated with searching and feeding behaviors of cotton aphids on leaves or leaf extracts of cotton plants. EPG results showed that there were some differences among behaviors of cotton aphids on 2 Bt cotton and 1 non-Bt cotton lines. Cotton aphids performed similarly to leaf surface extracts from 3 cotton lines; and leaf surface chemicals, mainly volatiles and waxes, were almost identical in the components and concentrations among the cotton lines. However, three cotton lines were quite different from each other in the densities of certain kinds of covering trichomes. Therefore, the relationships between the physical characteristics and the searching behaviors of cotton aphids on the three cotton lines were constructed as the regression equations. Glandular trichomes and covering trichomes with 5 branches influenced the cotton aphids' searching behaviors effectively; and other trichomes with other branches affected aphids in varying ways. These results demonstrated that leaf surface physical factors of transgenic Bt cotton lines different from their parental non-Bt line could affect the penetration behaviors of non-target cotton aphids. Cotton aphids penetrate and feed more easily on two Bt cotton lines than on the non-Bt cotton line.     

Bt毒蛋白在转Bt基因棉中的表达及其在害虫-天敌间的转移

以常规棉泗棉3号作为对照,采用酶联免疫生测法（ELISA）和室内生物测定法,研究了转Bt基因棉新棉33B和GK-12不同组织器官中Cry1Ac或Cry1Ab毒蛋白的表达及其向靶标害虫（棉铃虫）、非靶标害虫（棉蚜）以及天敌（龟纹瓢虫）的传递和影响。研究结果表明,新棉33B各组织器官中Bt毒蛋白的表达量较高,为79.7～1 390.0 ng/g鲜重,GK-012较低为165～2640 ng/g鲜重。在花盛期,新棉33B各组织器官中Bt毒蛋白的表达量依次为：柱头、花 >子房、花瓣>群尖;而5～7叶期的初展嫩叶、现蕾初期的幼蕾及花铃期的幼铃表达量相当,而且与花盛期群尖的表达量没有明显区别。同样处于花盛期的GK-12,其各组织器官中Bt毒蛋白的表达量依次为：花药>柱头>花瓣>群尖>子房;而5～7叶期的初展嫩叶、现蕾初期的幼蕾及花铃期的幼铃表达量相当,而且与花盛期群尖的表达量没有明显差异。常规对照棉的幼铃、花药、柱头以及子房中痕量Bt毒蛋白的存在可能与传粉昆虫等的活动有关。在转Bt基因棉田采集的棉蚜和棉铃虫老龄幼虫,其体内均可检测到Bt毒蛋白;在新棉33B棉田采集的龟纹瓢虫幼虫和成虫体内也可检测出Bt毒素。当以Bt棉田的棉蚜饲喂龟纹瓢虫时,龟纹瓢虫的生长发育、存活以及繁殖等基本没有受到影响。     

Effect of gramine on the feeding behavior of the aphids Schizaphis graminum and Rhopalosiphum padi

The effects of the indole alkaloid gramine on the behavior of the aphids Schizaphis graminum and Rhopalosiphum padi feeding on barley seedlings and on artificial diets were studied. On barley cv. F. Union, which lacks gramine, S. graminum ingested from phloem tissue for 30–80 min and non-phloem for 20–40 min, over a period of 3 h. In cultivar Datil S, gramine was found only in the epidermis and parenchyma mesophyll cells. On this cultivar, the non-phloem wave form of S. graminum was not observed. On F. Union, R. padi ingested non-phloem with short periods of ingestion from phloem. On cv. Datil S, this aphid did not show the non-phloem wave form. In experiments performed with cv. F. Union seedlings that contained exogenous gramine S. graminum did not ingest from phloem. Exogenous gramine was found only in the vascular bundles. It is suggested that gramine content and location may affect the feeding behavior of aphids in barley.

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Résumé Les effects de la gramine sur le comportement alimentaire des pucerons Schizaphis graminum et Rhopalosiphum padi on été étudiés en plantules d'orge (Hordeum distichum) et aussi avec des diètes artificielles à l'aide d'un moniteur électronique. S.graminum se nourri pendant 30–80 minutes à partir du phloème et il a pris 20–40 minutes en se nourrisant d'autres tissues divers, d'un total de 3 heures d'exposition à la plante. Dans la culture Datil S la gramine a été trouvée seulement dans les cellules de l'epidermis et du parenchyme du mesophyle. Dans ce cas, l'onde non-phloematique de S. graminum, n'a été pas observé; le temps pour le première onde X a été plus prolongé par rapport à la culture F. Union. Dans la culture F. Union, R. padi se nourri principalement de tissue non-phloematique (35–100 minutes) et du phloème par des brèves périodes (15–25 minutes). Dans le cas de la culture Datil S ce puceron n'a pas montré l'onde X. D'autre part, quand les plantules de F. Union ont été poussées dans des solution avec gramine, S. graminum ne se nourri pas du phloeme, tandis que R. padi montre un comportement similaire a celui-ce observé avec plantules sans gramine. La gramine absorbé par les plantules a été retrouvée seulement dans les faisceaux vasculaires. D'autre part, la gramine dans des diètes artificielles agit comme repulsif alimentaire à partir de concentrations de 0,5 mM. Avec des diètes contenant 3 mM de gramine l'alimentation des pucerons a été inhibée. Pourtant, ces resultats sugèrent que le contenuet et la localisation de la gramine peuvent modifier le comportement alimentaire des pucerons en plantules d'orge.

     

Characteristics of three cotton varieties and their impact on feeding and growth of cotton armyworm

This study investigated morphological and biochemical characteristics of CB9, CB10 and SR05 cotton varieties and observed their effect on feeding and growth of cotton armyworm Spodoptera litura. Morphological characters of plant architecture, branching, color, hairiness, trichome density and boll size indicated that CB9 is a bushy, well developed, branched, light bronze colored and hairy variety with number of trichomes 193/cm² and boll weight 5.5–6.0 g/boll. Both CB9 and CB10 bear normal leaves and spherical bolls whereas SR05 has well‐ventilated branching, okra shaped and ventrally arranged light bronze colored leaves and oval bolls ranging 4.0–4.5 g/boll. Biochemical analysis indicated significant differences in starch and protein contents, which range 11.4–21.3 and 17.5–30.6%, respectively. The lowest percentages of starch and protein were found in SR05 and CB9, respectively. Cotton varieties showed significant effects on second, third, fourth and fifth instar larval weight and they attained the highest weights (22.7, 133.8, 168.2 and 1190.2 mg, respectively) when fed SR05. Larvae and moths fed SR05 also showed the significantly highest cocoon, exuviae, and adult male and female weights (434.5, 19.2, 161.3 and 232.4 mg, respectively). The cotton armyworm showed the significantly highest growth index (1.5) as well as lowest feeding index (0.05) on SR05. Results of this study indicated that SR05 is suitable for larval feeding and development, and suggest that this variety is least suitable for cotton growers in areas where S. litura is a major pest.     

Impact of transgenic cotton varieties on activity of enzymes in their rhizosphere

The impact of five Bacillus thuringiensis (Bt) cotton varieties and their respective isogenic non-Bt(NBt) isolines (ANKUR-2534, MECH-6304, RCH-317, ANKUR-651 and MECH-6301) was assessed on the key soil enzymes i.e., dehydrogenase, alkaline phosphatase and urease in their rhizosphere at four growth stages of the crop, namely vegetative, flowering, bolling and harvesting. These varieties were grown on farmer's field in villages 22 miles and 24 miles of Ganganagar District of Rajasthan State in India. Results showed that dehydrogenase, alkaline phosphatase and urease activities were higher in rhizosphere of Bt isolines as compared to NBt isolines of all the varieties. Except phosphatase, differences in dehydrogenase and urease activities in rhizosphere of Bt and NBt isolines of all five varieties were significant (P < 0.05). Maximum enhancement in the three enzymes activities was observed in MECH-6304 Bt isoline rhizosphere. Maximum and minimum activities of dehydrogenase and urease were observed in MECH-6304 and RCH-317 Bt isolines, respectively, whereas phosphatase activity was maximum and minimum in MECH-6304 and ANKUR-651 Bt isolines, respectively. Maximum dehydrogenase and urease activities were observed at boll formation and minimum at flowering and harvesting stage, respectively, while maximum phosphatase activity was observed at vegetative stage and minimum at harvesting stage. In conclusion, all the studied Bt isolines of cotton varieties showed no adverse effect on dehydrogenase, alkaline phosphatase and urease activities in the rhizosphere.     

棉铃虫取食转Bt棉后蛹的抗寒力测定

在棉铃虫HelicoverpaarmigeraH櫣bner人工饲料中分别添加转Bt基因棉叶粉和常规棉叶粉饲喂幼虫,经滞育诱导后,发现2个处理间棉铃虫蛹的滞育率相似,2个处理间滞育蛹的自由水和结合水含量没有差异;但取食含Bt棉叶粉人工饲料的棉铃虫滞育蛹的过冷却点和结冰点显著高于对照组,蛹重及与抗寒性有关的脂肪和糖原含量均显著低于对照组。     

转基因棉花对棉铃虫天敌寄生率的影响

采用分期接虫、分期回收法研究常规棉与转基因棉花品种 (系 )上棉铃虫寄生性天敌在不同棉花品种上的寄生作用。结果表明 ,无论是第 2代棉铃虫发生期间还是第 3 ,4代棉铃虫发生期间 ,无论是棉铃虫卵期还是幼虫期 ,转基因棉花品种 (系 )的棉铃虫卵、幼虫寄生率均显著低于常规棉花品种上的寄生率。棉铃虫卵期寄生蜂主要是拟澳洲赤眼蜂 ,幼虫寄生蜂为棉铃虫齿唇姬蜂等。由此看出转基因棉对棉铃虫寄生性天敌存在非亲和性。     

Evaluation of transgenic cotton varieties and a glyphosate application on seedling disease incidence

A study was conducted to determine whether stand densities of transgenic cotton (Gossypium hirsutum) varieties, with or without glyphosate, were similar to conventional varieties of the same lineage group in Georgia and Mississippi. Transgenic and conventional cotton varieties were placed into five lineage groups of related varieties and seedling disease was evaluated in three greenhouse tests and a field trial using Rhizoctonia solani AG-4. Seed vigor was determined by standard germination studies were conducted evaluating conventional and transgenic varieties of similar lineage. Results showed that no interactions occurred for the heights and dry weight data across treatments within the lineage groups in any of the experiments. No interactions were shown between stand densities at different inoculum rates and inoculated versus uninoculated pots (plots). Across all greenhouse studies, stand counts of PM 1220 were similar to the transgenic varieties PM 1220 RR and PM 1220 B/RR with or without a glyphosate application. In the field trial, PM 1220 B/RR + glyphosate had significantly lower stands than all other treatments expect PM 1220 RR (no glyphosate treatment) prior to and after glyphosate application. Stand densities for varieties within the lineage group DPL 5415 were also inconsistent when compared between the greenhouse and field trials with no apparent trends occurring. However, the Coker 312 varieties containing glyphosate tolerance had consistently lower stand counts compared to the conventional variety of Coker 312 but only during the greenhouse studies. Seed germination of Coker 312 could not be correlated with either the greenhouse or field trial data. In general, the commercially available varieties such as PM 1220, DPL 5690, DPL 5415, and DPL 50 with glyphosate tolerance had similar stand count, height, and dry weight data when compared to the conventional varieties from the same lineage group regardless of a glyphosate application. When differences did occur, no consistent trends could be determined within these four lineage groups. An erratum to this article is available at .     

Evaluation of transgenic cotton varieties and a glyphosate application on seedling disease incidence

A study was conducted to determine whether stand densities of transgenic cotton (Gossypium hirsutum) varieties, with or without glyphosate, were similar to conventional varieties of the same lineage group in Georgia and Mississippi. Transgenic and conventional cotton varieties were placed into five lineage groups of related varieties and seedling disease was evaluated in three greenhouse tests and a field trial using Rhizoctonia solani AG-4. Seed vigor was determined by standard germination studies were conducted evaluating conventional and transgenic varieties of similar lineage. Results showed that no interactions occurred for the heights and dry weight data across treatments within the lineage groups in any of the experiments. No interactions were shown between stand densities at different inoculum rates and inoculated versus uninoculated pots (plots). Across all greenhouse studies, stand counts of PM 1220 were similar to the transgenic varieties PM 1220 RR and PM 1220 B/RR with or without a glyphosate application. In the field trial, PM 1220 B/RR + glyphosate had significantly lower stands than all other treatments expect PM 1220 RR (no glyphosate treatment) prior to and after glyphosate application. Stand densities for varieties within the lineage group DPL 5415 were also inconsistent when compared between the greenhouse and field trials with no apparent trends occurring. However, the Coker 312 varieties containing glyphosate tolerance had consistently lower stand counts compared to the conventional variety of Coker 312 but only during the greenhouse studies. Seed germination of Coker 312 could not be correlated with either the greenhouse or field trial data. In general, the commercially available varieties such as PM 1220, DPL 5690, DPL 5415, and DPL 50 with glyphosate tolerance had similar stand count, height, and dry weight data when compared to the conventional varieties from the same lineage group regardless of a glyphosate application. When differences did occur, no consistent trends could be determined within these four lineage groups.     

An energy budget approach for evaluating the biocontrol potential of cotton aphid (Aphis gossypii) by the ladybeetle Propylaea japonica

Biological control of economically important crop pests is an important component of integrated pest management (IPM) strategies. Predator–prey energy relationships are critical to the success of biocontrol strategies; however, these relationships are often ignored in many IPM programs. In this study, the biocontrol potential of cotton aphid, Aphis gossypii (Glover) (Hemiptera: Aphididae), by the ladybeetle Propylaea japonica (Thunberg) (Coleoptera: Coccinellidae) was estimated in terms of energy budgets calculated at 27 ± 1 °C. The energy equivalent of prey subjects (aphids) consumed was estimated from bomb calorimetry and partitioned into the energy associated with ingestion, assimilation, respiration, reproduction, and waste for each developmental stage of the lady beetle. The average assimilation efficiencies for larval and adult ladybeetles were 88.2 and 91.1%, respectively, whereas net ecological efficiencies were 17.6% for larvae and 2.6% for adults. Similarly, assimilation efficiencies of cotton aphids were 71.5 and 74.4% for nymphs and adults, respectively. Based on energy budget calculations, approximately 520, 3‐day‐old aphids and 5 356, 3‐day‐old aphids were estimated to be consumed by the ladybeetle larval stage and the female adult stage, respectively. These estimates were similar to the actual number of aphids consumed by the ladybeetles, based on actual counts. The current data demonstrate that P. japonica is an important natural enemy of the cotton aphid, and that predator–prey energy relationships can play a critical role in biocontrol strategies and IPM programs.     

取食转基因抗虫棉上的棉蚜对粉舞蛛存活和发育的影响

本文以转双价基因棉花SGK321、棉蚜Aphis gossypii和粉舞蛛Alopecosa pulverulenta为对象,研究了捕食转基因植物上的植食性害虫对多食性捕食性天敌的影响。结果表明,粉舞蛛可以猎食棉蚜,但单独捕食棉蚜不足以长期维持若蛛的生存和发育; 与果蝇混合饲养,能显著提高若蛛存活率和体重。在猎物过量或数量不足的情况下,单独捕食转基因棉或常规棉上的棉蚜,若蛛的生存曲线和体重差异不显著。在猎物过量的条件下,用转基因棉上的棉蚜与果蝇混合饲养,若蛛的存活率显著高于用常规棉上的棉蚜与果蝇混合的处理; 但这两种处理下,若蛛的体重差异不显著。在猎物数量不足的情况下,用转基因棉或常规棉上的棉蚜与果蝇混合饲养,若蛛的存活率和体重差异都不显著。可见,转双价基因棉花SGK321上的棉蚜对粉舞蛛的存活和发育没有显著的不利影响。     

Effect of cotton cultivar on development and reproduction of Aphis gossypii (Homoptera: Aphididae) and its predator Propylaea japonica (Coleoptera: Coccinellidae)

The effects of three cotton cultivars with low ('ZMZ13'), medium ('HZ401'), and high ('M9101') gossypol contents on the development, reproduction, and survival of Aphis gossypii Glover and its predator Propylaea japonica (Thunberg) were investigated. Developmental duration and immature survivorship did not vary between aphids on the three cultivars, whereas A. gossypii feeding on M9101 (high gossypol cultivar) displayed significantly shorter adult longevity and lower fecundity than aphids fed on 'ZMS13' and 'HZ401'. Free fatty acid content in cotton aphids reared on 'M9101' was greater than in those reared on 'HZ401' and 'ZMS13'. No significant differences in survival and lifetime fecundity of P. japonica were observed between P. japonica fed cotton aphids reared on the three different cultivars. P. japonica fed aphids from 'M9101' showed a significantly shorter developmental period and greater adult weight than those fed aphids from the other two cultivars. The decreased larval developmental duration and increased adult weight of P. japonica fed cotton aphids reared on the high gossypol-containing cultivar might have been caused by the high fatty acid content of the prey aphids. Our results indicate that high gossypol in host cotton had an antibiotic effect on A. gossypii and showed a positive effect on growth and development of P. japonica at the third trophic level. This suggests compatibility between one form of host plant resistance and biological control by predators. The allelochemical contents should be taken into account in integrated pest management for their effects on both herbivores and entomophagous insects.     

棉田棉铃虫寄生峰对常规棉及转Bt棉品种的趋性反应

连续4年采用人工定期释放棉铃虫卵、幼虫和定期回收法,研究了不同棉花品种与棉铃虫卵期、幼虫期寄生蜂种群数量变化的关系．通过对卵、幼虫寄生率反正弦转换后进行方差分析表明,无论是在棉铃虫卵期还是在其幼虫期,转基因棉田中棉铃虫卵和幼虫的被寄生率始终显著低于其亲本对照棉．运用“Y”型嗅觉仪测定转基因棉及其亲本对照棉对棉铃虫幼虫寄生蜂——中红侧沟茧蜂的选择性行为反应,用成对数据进行方差分析,并进行了“T”测验．结果表明,转基因棉对棉铃虫寄生蜂有较强的忌避反应,且取食转基因棉的棉铃虫幼虫与被害转基因棉两者的共同组合与单独被害棉之间对寄生蜂的忌避效应基本一致．     

转Bt基因棉花及其受体品种主要挥发性物质的测定

应用顶空进样气质联机系统（Headspace-GC-MS)测定了转Bt基因棉花及其对照亲本主要挥发性物质。结果表明棉花营养器官和繁殖器官的主要挥发性物质的差异,棉花植株现蕾期前,叶片中挥发性物质以α-蒎烯为主,而现蕾后,蕾、花和铃中主要以β-月桂烯为主。研究初步发现,外源Bt杀虫蛋白表达对棉花自身主要挥发性物质的合成不会造成不利影响。     

Interactive effects of elevated CO2 and cotton cultivar on tri-trophic interaction of Gossypium hirsutum, Aphis gossyppii, and Propylaea japonica

Information on the effects of enriched CO2 on both the chemical composition of plants and the consequences of such changes for performance of a herbivore and its predator is an important first step in understanding the responses of plants and insects to global environmental change. We examined interactions across three trophic levels, cotton, Gossypium hirsutum, an aphid herbivore, Aphis gossypii Glover, and a coccinellid predator, Propylaea japonica (Thunberg), as affected by elevated CO2 concentrations and crop cultivars. Plant carbon:nitrogen (C:N) ratios, condensed tannin, and gossypol content were significantly higher, and nitrogen content was significantly lower in plants exposed to elevated CO2 levels compared with that in plants exposed to ambient CO2. Cotton aphid survivorship significantly increased and free fatty acid content decreased with increased CO2 concentrations. No significant differences in survival and lifetime fecundity of P. japonica were observed between cultivars and CO2 concentration treatments. However, stage-specific larval durations of the lady beetle were significantly longer when fed aphids from elevated CO2 concentrations. Our results indicate that high gossypol in the cotton host plant had an antibiotic effect on A. gossypii and produced a positive effect on growth and development of P. japonica at the third trophic level. However, elevated CO2 concentrations showed a negative effect on P. japonica. We speculate that A. gossypii may become a more serious pest under an environment with elevated CO2 concentrations because of increased survivorship of aphid and longer development time of lady beetle.     

Electrical penetration graph analysis of the feeding behavior of soybean aphids on soybean cultivars with antibiosis

The soybean aphid, Aphis glycine Matsumura (Hemiptera: Aphididae), is a major pest of soybean. In the current study, we used the Electrical Penetration Graph technique to study feeding behavior of soybean aphids on antibiotic-resistant soybean lines KS1621, KS1613, and KS1642, and a susceptible soybean line, KS4202. We observed that soybean aphids spent significantly shorter periods of time in the sieve element phase but slightly more times in nonprobing phases in all three resistant lines than in the susceptible control. Our study suggests that resistance factors exist in the phloem of the resistant soybean lines, and that these lines may contain antixenosis in addition to antibiosis.     

Effect of bombesin on feeding behavior

Peripherally-administered bombesin and gastrin-releasing peptide produce potent, dose-related, and specific reductions of food intake at test meals in rats. Similar effects on meal size are observed after intraperitoneal injections in mice and after intravenous infusions in baboons and humans. The mechanism for this effect is unknown, but the action of bombesin is not blocked by complete subdiaphragmatic vagotomy, by a variety of peripheral endocrine and neural ablations, or by lesions of the area postrema or hypothalamus. Hypothalamic injections of bombesin produce small but specific reductions of food intake; the relationship of this central effect to the peripheral effect of the peptide is unknown. Bombesin and bombesin-like peptides may play roles in the regulation of meal size.