幼虫食物对甜菜夜蛾生长发育、繁殖及飞行的影响

报道了人工饲料、圆白菜和玉米苗三种食物对甜菜夜蛾 Ｓｐｏｄｏｐｔｅｒａ ｅｘｉｇｕａ 发育历期、蛹重以及成虫产卵和飞行能力的影响。幼虫取食人工饲料时发育历期最短, 蛹最重 （１３８ ｍ ｇ） , 产卵量最高 （６４３ 粒） ; 在１２ ｈ 的吊飞测试中, 成虫飞行距离最远 （２５５ ｋ ｍ ） , 飞行时间最长 （６２ ｈ） ,飞行超过１０ ｋ ｍ 的个体占６７９ ％ , 超过５ ｈ 的占６０７ ％ 。幼虫取食玉米苗时发育历期最长, 蛹最轻 （５２ ｍ ｇ） , 产卵量最低 （４１６ 粒） , 成虫仅能飞行３３ ｋ ｍ , １７ ｈ , 飞行超过１０ ｋ ｍ 或５ ｈ 的个体均仅占４２ ％ , 各项指标均显著低于人工饲料组。幼虫取食圆白菜时各项指标与人工饲料组基本相似 （ 幼虫历期和蛹重除外） , 而显著优于玉米苗组 （ 幼虫历期除外） 。这些结果表明, 幼虫食物对甜菜夜蛾的生长发育、产卵及飞行能力均有显著的影响, 因而是影响其个体发育、种群增长及种群动态的重要因素之一。同时, 由于取食本人工饲料的各项指标均优于其它两种食料植物, 因而可作为饲养甜菜夜蛾的实用饲料。     

寄主植物对甜菜夜蛾的发育和繁殖及体内酯酶活性的影响

在恒温(2 8±1 )℃条件下考察了葱、苋菜、豇豆、蕹菜、菜心5种寄主植物对甜菜夜蛾SpodopteraexiguaH櫣ｂｎｅｒ的营养效应及体内羧酸酯酶、乙?铛ッ富钚缘挠跋?,结果表明,不同寄主植物对甜菜夜蛾幼虫和蛹的发育历期、存活率、蛹重、雌成虫产卵量等有显著影响,其中对雌成虫产卵量的影响最大。雌成虫产卵量最高为取食菜心的处理,其次是取食葱的处理。寄主植物对甜菜夜蛾体内羧酸酯酶、乙酰胆碱酯酶活性也有显著影响,但这些酶的活性与发育历期、存活率、产卵量无明显相关性。在进行预测预报、田间防治时应充分考虑寄主植物对甜菜夜蛾发育历期、产卵量、解毒酶活性的影响。     

四种食料植物对八字地老虎生长发育和繁殖的影响

研究了油菜、甜菜、白菜和莴苣 4种食料植物对八字地老虎Agrotisc nigrumLinnaeus幼虫发育历期、蛹期、蛹重、成虫寿命和产卵量的影响。幼虫取食油菜时发育历期最短 (1 5 4d) ,蛹最重 (2 0 3 5mg) ,产卵量最多 (3 89 5粒 ) ,甜菜次之。幼虫取食莴苣时发育历期最长 ,蛹最轻 (1 3 6 1mg) ,产卵量最少(1 44 7粒 )。 4种食料植物对寄主的蛹期和成虫的寿命没有显著的影响     

草地贪夜蛾对2种豆科蔬菜的取食和产卵选择性及其适应性研究

草地贪夜蛾Spodoptera frugiperda是一种多食性昆虫,为明确该害虫对不同寄主的选择性和适生性,本文比较了草地贪夜蛾对玉米Zea mays、豇豆Vigna unguiculata和四季豆Phaseolus vulgaris等3种寄主的取食及产卵偏好性,并分析了取食不同寄主对其生长发育及繁殖的影响。结果表明：草地贪夜蛾低龄幼虫（初孵幼虫和2龄）对玉米叶和豇豆叶表现出取食偏好性,而高龄幼虫（3龄和5龄）对3种寄主不同组织的取食选择性无明显差异;草地贪夜蛾取食3种寄主植物均可以完成世代发育,但取食豇豆叶和四季豆叶的幼虫历期、蛹历期显著变短,化蛹率、羽化率显著降低;取食豇豆叶对其蛹重、成虫寿命无显著影响,但取食四季豆叶的蛹重显著变轻、雄成虫寿命显著变短;种群生命表参数显示,草地贪夜蛾在3种寄主上的繁殖力表现为玉米叶（1 138.29）>豇豆叶（1 179.00）>四季豆叶（585.50）,处理间差异显著;取食2种非嗜好寄主的种群内禀增长率（rm）和周限增长率（λ）均显著降低,平均世代历期（T）显著延长,取食豇豆叶的雌雄性比显著降低;草地贪夜蛾对寄主玉米具有明显的产卵偏好性,选择豇豆和四季豆的产卵量仅占植物着卵量的4.19%和18.23%,显著低于玉米着卵量。结果表明草地贪夜蛾偏好选择玉米进行取食和产卵,但在豇豆和四季豆寄主植物上可以实现种群繁衍,当其种群密度大时存在转移为害豇豆和四季豆的潜在风险。     

不同食物对甜菜夜蛾生长发育参数的影响

选择上海地区近年甜菜夜蛾Spodoptera exigua(Hübner)发生比较严重的甘蓝、豇豆、大葱、芦笋4种寄主植物,在温度(27±1)℃,相对湿度70%±5%,光照L:D=14:10的条件下研究了不同寄主植物对甜菜夜蛾发育特征的影响。结果表明,不同寄主植物饲喂甜菜夜蛾,甜菜夜蛾幼虫发育历期、存活率、蛹重、成虫寿命、净生殖力和内禀增长率等参数在寄主植物间有显著差异。用甘蓝饲喂的甜菜夜蛾雌虫产卵量明显高于取食大葱和芦笋的。同样,取食甘蓝的甜菜夜蛾蛹重、净生殖力和种群内禀增长率等参数明显高于取食大葱和芦笋的,说明甘蓝与其他寄主植物相比提供了较好质量的食物。     

草地贪夜蛾对水稻和玉米的取食和产卵选择性与适合度

【目的】明确草地贪夜蛾Spodoptera frugiperda对寄主植物水稻和玉米的取食和产卵选择性与适合度,进而分析草地贪夜蛾对水稻的为害风险。【方法】采用自由选择法,测定草地贪夜蛾对水稻和玉米的取食、产卵选择性。调查取食水稻和玉米苗的草地贪夜蛾的生长发育、存活率、繁殖力的差异,用种群增长趋势指数(I)评价水稻对草地贪夜蛾的适合度。【结果】草地贪夜蛾对水稻和玉米的取食和产卵选择性存在显著差异。接虫后2-48 h,幼虫对玉米的取食选择率随时间延长而逐渐增加,而幼虫对水稻的取食选择率随时间延长而逐渐降低;接虫后48 h,2龄幼虫和4龄幼虫对玉米的取食选择率分别为93.06%和59.72%,分别是对水稻的取食选择率的66.95倍和21.48倍。自由产卵6 d,在玉米上的产卵量是在水稻上的8.64倍。与取食玉米苗的相比,取食水稻苗的草地贪夜蛾幼虫发育历期延长,卵孵化率、幼虫存活率、化蛹率和成虫羽化率均显著降低,雌性比率下降,雌成虫寿命显著缩短,单雌产卵量显著减少。取食玉米苗的草地贪夜蛾的种群增长趋势指数(I)为165.93,其在水稻上的相对适合度为0.21。【结论】相较于水稻,草地贪夜蛾在玉米上表现出更高的适合度,其偏好在玉米上取食和产卵。水稻不是目前侵入我国的草地贪夜蛾的嗜食寄主,但其可以通过取食水稻幼苗正常生长发育并完成生活史,在其种群密度较大、嗜食寄主植物缺乏时存在转移为害水稻的潜在风险。     

3种人工饲料对草地贪夜蛾生长发育及繁殖力的影响

草地贪夜蛾Spodoptera frugiperda(J.E. Smith)是2019年入侵我国的重要农业害虫,筛选出合适的人工饲料可为规模化繁育提供基础。本文通过组建实验种群生命表的方法,研究了3种人工饲料对草地贪夜蛾生长发育、繁殖力以及种群增长潜能的影响,以玉米叶饲养的作为对照。结果表明,3种人工饲料对草地贪夜的饲养效果具有明显差异。其中,以饲料Ⅱ饲养的结果最理想,除幼虫-蛹发育历期(如雌性个体,23.63 d)比对照(20.98 d)略有延长外,幼期存活率(88.00%)、雌性蛹重(243.90 mg)、雄性蛹重(251.60 mg)、产卵量(845.90粒)等指标均优于对照,生命表参数中的净生殖力R_0(346.29)、内禀增长率r_m(0.1859)、周限增长率λ(1.2043)也高于对照。用饲料Ⅰ饲养时,草地贪夜蛾能够完成世代发育,但存在幼虫-蛹的发育历期(41.56 d)明显延长、幼期存活率(36.00%)、产卵雌成虫比例低(25.00%)等问题,难以达到室内大量繁育的要求。而以饲料Ⅲ饲养的草地贪夜蛾仅能生长发育至5龄幼虫,不能完成世代发育。综合相关生物学指标来看,饲料Ⅱ是饲养草地贪夜的适宜人工饲料。     

染料标记对斜纹夜蛾生长发育及成虫飞行能力的影响

以斜纹夜蛾Spodoptera litura为研究对象,将染料添加到半人工饲料中饲喂幼虫,评价其对该虫生长发育和成虫飞行能力的影响,以期为开展该虫的田间诱集和扩散行为研究提供标记方法。结果表明,添加不同浓度苏丹红7B、苏丹蓝Ⅱ和龙胆紫的半人工饲料饲养斜纹夜蛾幼虫,含0.006%苏丹红7B的半人工饲料幼虫存活率高,成虫标记效果好。进一步研究显示,取食含0.006%苏丹红7B半人工饲料的斜纹夜蛾幼虫发育历期、蛹重以及成虫寿命、体长、翅展及飞行能力等与对照相比均无显著差异。含0.006%苏丹红7B半人工饲料饲料对斜纹夜蛾的生物学无显著影响,标记效果显著,操作简单,适合于大规模标记斜纹夜蛾成虫。     

草地贪夜蛾对不同品种玉米的适应性比较研究

为了解不同玉米品种对草地贪夜蛾生长发育的影响,本文通过比较草地贪夜蛾Spodoptera frugiperda取食2种糯质型玉米(明玉1203和苏玉糯5号)与3种普通玉米(苏玉29、苏玉30和郑单958)后的发育历期、死亡率、蛹重、成虫畸形率、繁殖力与幼虫取食选择率等生物学参数,分析了草地贪夜蛾对不同品种玉米的适应性差异.结果表明:以糯质型玉米饲养的草地贪夜蛾幼虫发育历期与成虫寿命均长于取食普通玉米的个体,而蛹重与单雌产卵量低于取食普通玉米的个体.草地贪夜蛾最高总体死亡率(50.82％)与成虫畸形率(41.38％)均来自于取食糯质型玉米明玉1203处理,而最低总体死亡率(37.29％)与成虫畸形率(12.50％)则分别来自于取食糯质型玉米苏玉糯5号和普通玉米苏玉30处理组.此外,仅6龄幼虫对不同玉米品种的取食偏好性存在显著差异,更倾向于取食普通玉米.综合可见,草地贪夜蛾对普通玉米的适应性好于糯质型玉米,且对糯质型玉米明玉1203的适应性最差.研究结果为所选品种玉米的安全生产与草地贪夜蛾的发生为害评估奠定了研究基础.     

草地贪夜蛾对5种寄主植物和6种杂草的取食选择性和适应性

为明确草地贪夜蛾Spodoptera frugiperda J. E. Smith对不同寄主植物和主要杂草的取食选择及适应性,以玉米Zea mays、甘蔗Saccharum officinarum、花生Arachis hypogaea、大豆Glycine max、香蕉Musa nana、稗草Echinochloa crusgalli、马唐Digitaria sanguinalis、牛筋草Eleusine indica、莎草Cyperus rotundus、马齿苋Portulaca oleracea、鹅肠草Malachium aquaticum作为寄主,采用叶碟法测定草地贪夜蛾各龄幼虫对5种寄主植物和6种杂草的取食偏好,并测定了不同虫态的发育历期、单头蛹重、化蛹率以及单雌产卵量等。结果表明,草地贪夜蛾在5种寄主植物和6种杂草上均可完成世代发育。寄主作物中,香蕉处理的草地贪夜蛾成虫前期最长,为29.66 d;甘蔗处理下草地贪夜蛾蛹重和化蛹率分别为250.44 mg和71.67%,显著低于玉米和花生处理的蛹重和化蛹率;草地贪夜蛾取食花生后单雌产卵量最高,为768.93粒,与玉米上产卵量差异不显著,香蕉上最低,为498.76粒;1~2龄幼虫对玉米和香蕉的取食选择率有显著差异,3~6龄幼虫对玉米取食选择率显著高于其他寄主植物。6种杂草中取食莎草的成虫前期最长30.21 d,且单雌产卵量最低526.33粒;取食鹅肠草蛹重最低188.00 mg;取食马齿苋化蛹率最低为72.37%;草地贪夜蛾取食马唐后其蛹重、化蛹率、单雌产卵量最高,与取食其它5种杂草有显著性差异;2~4龄幼虫更偏向取食马唐,与其它5种差异显著。研究结果表明：寄主植物种类对草地贪夜蛾的生长发育有显著影响,其中草地贪夜蛾对玉米和马唐具有较高的取食偏好。     

甜菜夜蛾群体繁殖及其对杀虫剂毒力敏感性测定

用黄豆粉、麦胚粉、酵母粉为主要营养成份研制成人工饲料,实现了甜菜夜蛾大量饲养及群体繁殖,与自然饲料相比,人工饲料饲养甜菜夜蛾幼虫存活与成虫产卵量明显增加,室内用浸渍法测定11种杀虫剂对甜菜夜蛾2龄幼虫的毒力,结果表明,田间甜菜夜蛾种群对除尽,米满,菜喜最敏感,其次是对抑太保,卡死克,毒丝本,高效灭百可,快灵,对锐劲特,氯氰菊酯,乙酰甲胺磷的毒力均已高度不敏感。     

Influence of whorl region from resistant and susceptible corn genotypes on fall armyworm (Lepidoptera: Noctuidae) growth and development

The effect of diets prepared from whorl tissue of resistant and susceptible corn genotypes, Zea mays L., on the larval growth, development, and physiology of fall armyworm, Spodoptera frugiperda (J. E. Smith), was analyzed. Larvae reared on an optimized artificial diet had a higher growth rate and developed faster than those reared on lyophilized whorl tissue from resistant and susceptible genotypes. Larvae reared on the resistant material were smaller and had a longer developmental period. Larvae reared on yellow-green and green whorl sections from resistant plants were significantly smaller than those reared on the same sections of susceptible plants. There was no significant difference in weight when larvae were reared on the yellow whorl regions from either resistant or susceptible lines. Physiological indices were determined for larvae fed resistant and susceptible lyophilized and fresh whorl material. Larvae fed resistant lyophilized material had significantly lower growth rate (GW) and efficiency of conversion of ingested food to body substance (ECI) than those reared on artificial diet or susceptible material. However, there were no significant differences in consumption index (CI), approximate digestibility (AD) and efficiency of conversion of digested food to body substance (ECD) between larvae reared on lyophilized tissue from resistant and susceptible genotypes. Larvae reared on fresh yellow-green whorl sections from resistant plants had significantly lower GW, ECI, and ECD than those reared on susceptible material. In contrast, no significant differences in any of the estimated food consumption and utilization indices were observed between larvae reared on fresh yellow whorl sections from resistant or susceptible plants. These results suggest that some components of whorls from resistant plants, especially the yellow-green region, inhibit food utilization in fall armyworm larvae.     

食物对棉铃虫生长发育及繁殖的影响

用棉花、花生、玉米及人工饲料作为食料,模拟幼虫田间取食习性,同时为雌蛾设立补充和无补充营养两个处理,研究了食物对棉铃虫 Helicoverpa armigera (Hübner) 生长发育及繁殖的影响。4种食料组幼虫历期之间有显著差异;雌、雄蛹重花生组显著小于其余三组。雌蛾腹部干重及其脂肪百分含量与雌蛹体重的排列顺序一样,雌蛾腹部干重人工饲料组显著大于棉花组和花生组。雌蛾寿命和繁殖受幼虫食料和成虫食物的双重影响。喂10%蜂蜜时,雌蛾寿命、交配率和产卵量在四个幼虫食料组之间没有显著差异。但喂以清水时,花生组雌蛾均未交配,寿命和产卵量显著小于其余三组。从同种幼虫食料来看,除人工饲料组外,其余3组雌蛾喂清水时的产卵量和寿命均比喂10%蜂蜜溶液时的显著下降。基于这些结果,作者认为棉花、玉米比花生更适合于棉铃虫的生长发育和繁殖。在田间自然栽培状态下,不同食料植物的糖分含量对棉铃虫生长发育和繁殖影响较大,含氮量的变化影响小。     

The effect of GNA lectin on the α-amylase activity of the beet armyworm,Spodoptera exigua Hb. (Lepidoptera: Noctuidae)

Beet armyworm (Spodoptera exigua Hb.) (Lepidoptera: Noctuidae) is the major pest of sugar beet (Beta vulgaris). Pesticide applications are the main method of the insect control. So, alternative method/s is/are needed to control this insect species. So, in the current study, the effect of Galanthus nivalis agglutinin (GNA) (snowdrop lectin) on beet armyworm α-amylase was studied. Measurement of the amylase activity of the larval midgut fed on artificial diet and sugar beet leaves showed that the enzyme activity was higher when the larvae fed on artificial diet. However, in both cases, the fourth instar larvae had the greatest amylase activity. Thus, fourth instar larvae were offered artificial diet containing 1 and 2% GNA. Both treatments of the lectin significantly reduced the α-amylase activity of the insect. For example, amylase activity of the fourth instar larvae in the control (fed only on artificial diet) was 2.62 Uml^?1 whilst the activity of the enzyme in the two treatments including diet containing 2 and 1% lectin was 1.45 and 1.75 Uml^?1, respectively. The achieved data showed that lectin, in addition to have toxic effect on the larval growth and development, affects the α-amylase activity of the insect gut.     

二种改进人工饲料对红脉穗螟生长发育和繁殖的影响

在温度(29±1)℃和相对湿度75%±5%条件下,研究了2种改进人工饲料和天然饲料椰子幼果对红脉穗螟Tirathaba rufivena Walker生长发育、繁殖力和营养的影响。结果表明:与天然饲料相比,用改进人工饲料饲养的红脉穗螟幼虫生长发育速度、幼虫存活率、蛹重及产卵量均提高;幼虫相对生长率(RGR)、食物利用率(ECI)及食物转化率(ECD)均显著提高,而相对取食量(RCR)则显著降低。表明红脉穗螟幼虫对2种人工饲料有很好的适应性,可用于大量饲养。     

Life table parameters, reproductive rate, intrinsic rate of increase, and estimated cost of rearing Podisus maculiventris (Heteroptera: Pentatomidae) on an artificial diet.

The impact of an insect-free artificial diet provided at nymphal and/or adult stage upon the developmental rate, life table parameters, and fertility table parameters was examined for Podisus maculiventris (Say). This study showed that when fed an insect-free artificial diet during both the nymphal and adult stage, developmental time was prolonged, preoviposition period was extended, and reproductive rate (R0) and intrinsic rate of increase (r) were significantly lower than when fed larval insect prey at both nymphal and adult stages. Additionally, feeding larval prey to adults reared as nymphs on an artificial diet significantly increased the proportion of fertile females, the number of eggs laid by mated females, the reproductive rate and intrinsic rate of increase, but the mean generation time was not significantly different. Likewise, feeding artificial diet to adults reared on larval prey resulted in a significant reduction in reproductive rate and intrinsic rate of increase. The "realized" cost to rear P. maculiventris on the artificial diet was calculated (as the cost to double the population size) using raw material cost, fertility table parameters and doubling time values. Raw material cost for rearing P. maculiventris colony on Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) was only 1.4 times higher than the cost of artificial diet raw materials required to rear the same size colony. However, the realized cost of rearing was 3.5 times higher when rearing on artificial diet because of the prolonged developmental time and reduced reproductive output. The cost efficiency of rearing a beneficial insect on an artificial diet that decreases the intrinsic rate of increase of a colony is discussed, as well as the advantages and disadvantages of supplementing adult diets with natural prey at the reproductive stage.     

Biological and biochemical characteristics for quality control of Harmonia axyridis (Pallas) (Coleoptera, Coccinellidae) reared on a liver-based diet

Biological and biochemical parameters of a flightless strain of Harmonia axyridis, fed on a pork liver-based artificial diet and on Ephestia kuehniella eggs as controls, were compared. The diet-grown larvae showed a significantly longer developmental time and a lower adult emergence rate compared to control larvae. The weights of the newly emerged adults were significantly higher for adults fed E. kuehniella eggs during their larval stages than fed the artificial diet. In contrast, larval food source had no effect on the duration of the pre-oviposition period or adult longevity. For adults fed on E. kuehniella eggs as larvae, a significantly longer pre-oviposition period, lower daily weight gain and fecundity were found for the diet-fed females compared to those fed on E. kuehniella eggs throughout the life span. The adult food source had no significant effect on longevity and fertility. Lower amino acid and fatty acid contents (in particular C16:1 and C18:3n-3) were found for the prepupae and newly emerged females obtained from diet-reared larvae compared to controls. Deficiencies in fatty acids C16:1 and C18:3n-3 were also observed in females obtained from E. kuehniella egg-reared larvae and fed on diet from adult emergence. The analyses of the foods showed deficiencies in artificial diet, especially for some amino and fatty acids. The results suggest a non-optimal composition of the artificial diet and some possibilities for its improvement. However, this polyphagous predator could be reared from first instar larvae to fully reproductive adults on a pork liver-based artificial diet.     

Biology and life table studies of the oriental tobacco budworm,Helicoverpa assulta (Lepidoptera: Noctuidae), influenced by different larval diets

Development, survivorship, pupal weight, oviposition, and life table parameters of the oriental tobacco budworm, Helicoverpa assulta Guenée, were evaluated in the laboratory on an artificial diet, pepper (Capsicum frutescens L.), and tobacco (Nicotiana tobacum L.). We found that the average developmental time of immature stages was longest on tobacco (36.2 d), intermediate on pepper (34.4 d), and shortest on artificial diet (33.5 d). Immature survival from egg to pupa varied from 31% on tobacco, 43% on pepper, and 74% on artificial diet. Pupal weight ranged from 197.4 mg/pupa on tobacco, 233.1 mg/pupa on pepper and 253.4 mg/pupa on artificial diet. The average numbers of eggs laid by adults reared as larvae on the artificial diet, pepper, or tobacco were 614, 421 and 334 eggs/female, respectively. Numbers of remaining eggs in ovaries of the adult females reared as larvae on the artificial diet, pepper, or tobacco were 16, 26, and 42 eggs/female, respectively. The longevity of adult females developed from larvae reared on the three diets was not significantly different, whereas the longevity of male adults from the larvae reared on artificial diet was longer (16.8 d) than that for males reared on tobacco (13.8 d) and pepper (13.3 d). The intrinsic, finite, gross, and net rates of increase were highest for females reared as larvae on artificial diet, lowest for females emerging from larvae reared on tobacco, and intermediate for females emerging from larvae reared on pepper. Generation times and doubling time of H. assulta were shortest for larvae fed artificial diet, intermediate from larvae reared on pepper, and longest from larvae reared on tobacco. We concluded that the artificial diet was the most suitable larval diet of H. assulta followed by pepper, and tobacco.     

Host plant resistance in romaine lettuce affects feeding behavior and biology of Trichoplusia ni and Spodoptera exigua (Lepidoptera: Noctuidae)

Lettuce quality and yield can be reduced by feeding of several lepidopterous pests, particularly cabbage looper, Trichoplusia ni (Hübner), and beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae). Host plant resistance to these insects is an environmentally sound adjunct to conventional chemical control. In this study we compared the survival, development, and feeding behavior of cabbage looper and beet armyworm on two romaine lettuce cultivars, resistant 'Valmaine' and susceptible 'Tall Guzmaine'. Larval mortality of both species was significantly higher on resistant Valmaine than on susceptible Tall Guzmaine. The average weight per larva after feeding for 1 wk on Tall Guzmaine plants was 6 times (beet armyworm) and 2 times (cabbage looper) greater than that of larvae feeding on Valmaine plants. Significant reduction in larval growth on Valmaine compared with that on Tall Guzmaine resulted in a 5.9- (beet armyworm) and 2.6-d (cabbage looper) increase in larval duration and almost a 1-d increase in pupal duration. Average pupal and adult weights and successful pupation of cabbage looper and beet armyworm were reduced on Valmaine compared with Tall Guzmaine. The sex ratio of progeny did not deviate from 1:1 when larvae were reared on either Valmaine or Tall Guzmaine. The fecundity of cabbage looper and beet armyworm adults that developed from larvae reared on Valmaine was about one-third that of adults from Tall Guzmaine, but adult longevity did not significantly differ on the two lettuce cultivars. The two insect species showed different feeding preferences for leaves of different age groups on Valmaine and Tall Guzmaine. Cabbage loopers cut narrow trenches on the leaf before actual feeding to block the flow of latex to the intended site of feeding. In contrast, beet armyworms did not trench. The different feeding behavior of the two species on Valmaine may explain the superior performance of cabbage looper compared with beet armyworm.     

Effects of two artificial diets on the development and reproduction of Tirathaba rufivena (Walker) (Lepidoptera: Pyralidae)

Growth, survival, fecundity, and nutrition of Tirathaba rufivena (Walker) fed on two artificial and one natural diet were studied at 29±1°C and 75±5% relative humidity. Larvae reared on the two artificial diets showed faster growth and development, higher pupal survival and weight, and higher adult fecundity than those reared on a natural diet of young coconuts, Cocos nucifera L. The relative growth rate, efficiency of ingested food conversion, and efficiency of digested food conversion in larvae fed on artificial diets were significantly higher than those of larvae fed on young coconuts. The relative consumption rate of larvae fed on artificial diets was significantly lower than that of larvae fed on young coconuts. T. rufivena showed no significant degradation in ability to propagate after being reared on the artificial diet for five successive generations. These results indicated that two artificial diets are suitable for mass rearing of T. rufivena.