螟黄赤眼蜂对草地贪夜蛾卵寄生效果评价

为了明确螟黄赤眼蜂Trichogramma chilonis对草地贪夜蛾Spodoptera frugiperda (J.E. Smith)卵寄生效果,室内组建了螟黄赤眼蜂在草地贪夜蛾卵上的实验种群生命表,调查统计了释放螟黄赤眼蜂后田间草地贪夜蛾卵的寄生率和幼虫的虫口减退率,并分析了释放距离对寄生效果的关系。结果显示,螟黄赤眼蜂在草地贪夜蛾卵上的净生殖力R0=10.8407,内禀增长率rm=0.2220,周限生长率λ=1.2486,单雌平均产雌率R0′=13.8877。放蜂区草地贪夜蛾卵块寄生率64.44%,卵粒寄生率35.42%,显著高于对照区,释放赤眼蜂第7天田间草地贪夜蛾虫口减退率58.92%,防效50.50%。释放距离为5 m内螟黄赤眼蜂对草地贪夜蛾卵寄生效果的无显著影响。结果表明螟黄赤眼蜂对草地贪夜蛾卵有较高的寄生效能,田间释放螟黄赤眼蜂对草地贪夜蛾卵具较高的寄生率和明显的幼虫虫口减退率,释放螟黄赤眼蜂对降低草地贪夜蛾虫源基数起着重要的作用。     

东北地区四种本地赤眼蜂对草地贪夜蛾寄生能力及适应性研究

草地贪夜蛾Spodoptera frugiperda(Smith)是新入侵我国的重大危险性入侵害虫,赤眼蜂是我国生物防治的优势卵寄生蜂,可用于防治多种农林作物上的鳞翅目害虫。为检测东北地区本地赤眼蜂对草地贪夜蛾卵的生防潜能,筛选防治草地贪夜蛾的有效蜂种,本研究比较研究了松毛虫赤眼蜂、玉米螟赤眼蜂、黏虫赤眼蜂和稻螟赤眼蜂对草地贪夜蛾卵的寄生能力和发育适合度。结果表明,4种赤眼蜂均能寄生草地贪夜蛾卵,并完成发育,但其寄生能力和发育适合度存在显著差异。松毛虫赤眼蜂、玉米螟赤眼蜂和黏虫赤眼蜂对草地贪夜蛾卵块寄生率均高于80%,但仅松毛虫赤眼蜂对草地贪夜蛾卵表现出较高的卵粒寄生量。松毛虫赤眼蜂、玉米螟赤眼蜂和黏虫赤眼蜂子代羽化率和雌性比无显著差异,但松毛虫赤眼蜂比其它3种赤眼蜂的发育历期更短,而稻螟赤眼蜂对草地贪夜蛾卵的寄生能力和适合度均最差。研究结果将为应用本地赤眼蜂生物防治潜在入侵东北地区的草地贪夜蛾提供技术支撑。     

大草蛉对草地贪夜蛾捕食潜能研究

草地贪夜蛾Spodoptera frugiperda JE Smith于2018年底至2019年初入侵我国后,迅速扩散,并在半年内对西南地区的玉米生产造成为害。田间调查和观测研究表明,田间虽然可见该害虫的天敌,但由于天敌种群数量低,无法形成有效控害的模式。为研究大草蛉对草地贪夜蛾的控害潜能,本研究进行了捕食功能反应试验。结果表明,大草蛉成虫对草地贪夜蛾卵以及大草蛉3龄幼虫对草地贪夜蛾1龄幼虫的捕食效应均能够很好的拟合HollingⅡ功能反应模型。其中,大草蛉成虫对贪夜蛾卵的理论日最大捕食量、瞬时攻击率和处理时间分别为1115.56头、1.004和0.0009 d。大草蛉幼虫对贪夜蛾低龄幼虫的理论日最大捕食量、瞬时攻击率和处理时间分别为358头、1.074和0.003 d。结果表明大草蛉具备对草地贪夜蛾卵和低龄幼虫进行有效控害的潜力,为应用天敌昆虫防治草地贪夜蛾提供了理论依据。     

粤港两地田间发现夜蛾黑卵蜂与螟黄赤眼蜂寄生草地贪夜蛾

草地贪夜蛾是新入侵我国的重大危险性害虫,了解野外条件下天敌的发生情况对于挖掘和利用本地天敌资源开展生物防治有重要意义。2019年4月至7月,定期在广州及香港地区的玉米田中开展草地贪夜蛾发生情况调查时,发现野外两种卵寄生蜂寄生草地贪夜蛾。通过分子生物学方法鉴定为夜蛾黑卵蜂和螟黄赤眼蜂,并分别建立实验种群,为人工扩繁及田间应用打下基础,为利用本地天敌开展草地贪夜蛾生物防治提供重要参考。     

4种寄生蜂在草地贪夜蛾卵上的种群增长潜能及优势蜂种间竞争

为明确入侵性重大农业害虫草地贪夜蛾卵期优势寄生蜂种类,采用生命表方法评价了夜蛾黑卵蜂、短管赤眼蜂、螟黄赤眼蜂和松毛虫赤眼蜂这4种寄生蜂在草地贪夜蛾卵上的种群增长潜力,并观察比较了短管赤眼蜂和夜蛾黑卵蜂这两种优势蜂种在草地贪夜蛾卵上的竞争行为。结果表明,供试的4种寄生蜂对草地贪夜蛾卵均表现出良好的寄生适应性,内禀增长率（rm）与周限增长率（λ）从大到小依次为短管赤眼蜂（rm, 0.3449; λ, 1.4118）、夜蛾黑卵蜂（rm, 0.2842; λ, 1.3286）、螟黄赤眼蜂（rm, 0.1960; λ, 1.2165）和松毛虫赤眼蜂（rm, 0.1751; λ, 1.1913）。当夜蛾黑卵蜂与短管赤眼蜂竞争寄生同一草地贪夜蛾卵块时,两种蜂的子代羽化率均显著低于各自单独寄生时。草地贪夜蛾卵在被夜蛾黑卵蜂寄生后1 h、24 h及48 h均可被短管赤眼蜂寄生,夜蛾黑卵蜂的子代羽化率分别为21.15%（1 h）、36.68%（24 h）和25.52%（48 h）,均高于短管赤眼蜂的子代羽化率10.94%（1 h）、23.13%（24 h）和5.23%（48 h）;而当短管赤眼蜂先寄生时,虽然寄生后1 h、24 h和48 h的卵粒也能被夜蛾黑卵蜂寄生,但所羽化的子代均为短管赤眼蜂,羽化率分别为42.62%（1 h）、46.93%（24 h）和38.66%（48 h）。本研究表明,与螟黄赤眼蜂和松毛虫赤眼蜂相比,短管赤眼蜂和夜蛾黑卵蜂在草地贪夜蛾卵上表现出更强的种群增长潜能;夜蛾黑卵蜂与短管赤眼蜂竞争寄生同一寄主卵块时,两者寄生能力均会受到不同程度的抑制,但短管赤眼蜂的竞争力明显强于夜蛾黑卵蜂。     

不同寄主对草地贪夜蛾生长发育和繁殖的影响

草地贪夜蛾是入侵我国的重大农业害虫,严重威胁我国粮食安全。为明确该虫在不同寄主植物上的适合度,本文系统研究了草地贪夜蛾取食花生、荞麦和生姜3种寄主生长发育和繁殖情况,组建了实验种群生命表。结果表明:草地贪夜蛾在3种寄主植物上的繁殖力高低为花生(771.73粒)>荞麦(477.13粒)>生姜(209.22粒),卵的孵化率无显著差异,幼虫和蛹重均是花生>荞麦>生姜。草地贪夜蛾取食花生、荞麦和生姜后的净增殖率(R 0)分别为226.36、102.45和20.75,内禀增长率(r m)分别为0.16、0.13和0.06。研究发现,草地贪夜蛾在花生、荞麦和生姜3种寄主植物上均能实现种群繁殖,其中,花生是最适宜的寄主,荞麦次之,生姜相对较不适宜。     

黄玛草蛉幼虫对草地贪夜蛾卵和低龄幼虫的捕食能力

【目的】明确本地优势天敌黄玛草蛉Mallada basalis对入侵我国的重大农业害虫草地贪夜蛾Spodoptera frugiperda卵及低龄幼虫的捕食能力和生防潜力。【方法】在实验室条件下采用功能反应模型评价了黄玛草蛉2和3龄幼虫对草地贪夜蛾卵及1和2龄幼虫的捕食能力。【结果】黄玛草蛉幼虫对草地贪夜蛾卵和低龄幼虫的捕食量均随猎物密度的升高而增加,最后趋于捕食饱和状态,而其捕食率随猎物密度的升高而逐步下降,对不同发育阶段的草地贪夜蛾均表现为Ⅱ型功能反应。黄玛草蛉2龄幼虫对草地贪夜蛾卵及1和2龄幼虫的瞬时攻击率a分别为0.150, 0.084和0.094,处理时间Th分别为0.282, 0.333和0.519 h,理论日最大捕食量T/Th分别为85106粒、72072头和46.242头;黄玛草蛉3龄幼虫对草地贪夜蛾卵及1和2龄幼虫的瞬时攻击率分别为2.018, 0.288和0.259,处理时间分别为0.102, 0.311和0.375 h,理论日最大捕食量分别为235294粒、77170头和64000头。【结论】黄玛草蛉2和3龄幼虫对草地贪夜蛾卵和低龄幼虫均具较强的捕食能力,其中黄玛草蛉3龄幼虫比2龄幼虫具有更强的捕食效率。     

外来入侵新害虫草地贪夜蛾调查监测方法探讨

草地贪夜蛾Spodoptera frugiperda(Smith)是一种重要的外来入侵新害虫,目前已入侵我国14个省区500多个县区,对我国玉米等种植业造成严重威胁,加强该虫的监测与防控显得尤为必要而紧迫。本文针对入侵我国的"玉米型"草地贪夜蛾,在成虫数量、田间虫情和作物受害程度3个方面提出了一套较为系统的调查监测方法,可为监测明确该虫入侵虫源、发生数量、危害程度及其动态,确定发生分布区域、预测预报发生期、发生程度等提供方法依据。     

广东省草地贪夜蛾种群周年动态及发生特征

为了明确广东省草地贪夜蛾Spodoptera frugiperda(J. E. Smith)种群周年消长动态及发生特征,根据2020年和2021年广东省草地贪夜蛾性诱监测及田间调查数据,分析不同生态区草地贪夜蛾成虫及幼虫种群周年发生动态。结果表明：(1)草地贪夜蛾在广东省大部分冬种玉米区可以周年繁殖,仅在清远、韶关、河源等地未发现幼虫为害;不同地区之间草地贪夜蛾越冬虫源基数差异较大,粤西发生为害较重,珠三角及粤东地区发生相对较轻;(2)周年繁殖区草地贪夜蛾成虫和幼虫全年均可发生为害,而季节发生区一般于3-4月才零星始见草地贪夜蛾成虫和幼虫,且诱蛾量、幼虫种群数量及为害程度均相对较低;(3)广东省草地贪夜蛾种群消长动态呈多峰型,发生高峰期主要集中于5-10月,期间出现多个大小不等的高峰,但峰期、蛾量和虫量在不同地区之间差异较大。本研究明确了广东省不同生态区草地贪夜蛾种群的周年消长动态及发生特征,为广东省乃至全国草地贪夜蛾的早期预警和精准防控提供重要参考。     

利用mtCOI PCR-RFLP技术鉴别草地贪夜蛾与其他3种形态相近昆虫

【目的】田间调查发现草地贪夜蛾与甜菜夜蛾、斜纹夜蛾、粘虫常混合发生,传统的形态学鉴定方法不能快速鉴别出该虫,当前亟需快速鉴别该虫的方法。【方法】本研究分析了草地贪夜蛾与甜菜夜蛾、斜纹夜蛾、粘虫mtCOI基因序列的酶切位点,根据目的片段设计上游引物并进行PCR-RFLP验证。【结果】草地贪夜蛾个体在mtCOI片段的556~561 bp处均存在Sbf I内切酶酶切位点,斜纹夜蛾、甜菜夜蛾、粘虫均无Sbf I酶切位点。草地贪夜蛾PCR产物经过Sbf I内切酶酶切,可出现420 bp左右的特征带,斜纹夜蛾、甜菜夜蛾、粘虫种群均不能被Sbf I内切酶酶切。【结论】基于新设计引物扩增的mtCOI片段的PCR-RFLP方法可有效鉴别草地贪夜蛾与其他3个形态相近昆虫,研究结果为草地贪夜蛾的快速鉴别提供了方法。     

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...     

模拟降雨对草地贪夜蛾卵和幼虫的影响

为探究降雨对草地贪夜蛾Spodoptera frugiperda种群的影响,本研究通过室外模拟降雨研究了雨水冲刷对草地贪夜蛾卵和幼虫的影响。结果表明：在4种不同降雨强度0 mm/h（对照）、10.2 mm/h（中雨）、26.5 mm/h（暴雨）、42.8 mm/h（大暴雨）处理下,卵块的掉落率随着降雨强度的增加而增加;在暴雨、大暴雨条件下卵块的孵化率分别为75.14%、43.58%,显著低于对照和中雨;对比有无鳞毛层覆盖的卵块之间的掉落率和孵化率,二者在各个降雨强度之间差异不显著;对比玉米叶片不同位置卵块的掉落率和孵化率,在中雨降雨强度影响下,二者差异不显著,而在暴雨、大暴雨条件下,玉米叶片背面卵块的掉落率低于正面,孵化率高于正面。此外,在相同的降雨强度下,草地贪夜蛾幼虫（2龄、3龄、4龄、5龄）的掉落率随着龄期的增加而降低;当降雨强度增加时,3龄幼虫的掉落率增加。结果表明降雨,特别是暴雨和大暴雨,对草地贪夜蛾的卵和幼虫均有不利影响,为预测草地贪夜蛾种群提供一定依据。     

草地贪夜蛾幼虫在玉米和小麦上的取食和生长发育特性比较

【目的】评估草地贪夜蛾Spodoptera frugiperda转移至小麦上为害和暴发的风险。【方法】采用室内饲养观察与调查统计的方法,测定和比较了23℃下草地贪夜蛾在玉米和小麦上的取食和生长发育特性及种群生命表参数。【结果】草地贪夜蛾在小麦上可以完成世代,其3龄后幼虫取食小麦的取食量及体重指标显著地高于同处理后时间在玉米上取食的;而食物利用效率、幼虫存活率、幼虫发育历期、卵孵化率均显著低于取食玉米的。取食玉米和取食小麦的草地贪夜蛾的平均蛹重、产卵前期、单雌产卵量等指标间无显著差异。另外,生命表参数比较结果表明,取食玉米和取食小麦的草地贪夜蛾的平均世代周期(T)、内禀增长率(r_m)和周限增长率(λ)间均无显著差异,取食玉米的草地贪夜蛾的净增殖率(R₀)为303.55±2.04,显著高于取食小麦的。【结论】草地贪夜蛾取食小麦时,生长发育速度快,能够完成世代生活史,但其食物利用效率、种群繁殖能力等却均低于取食玉米时,说明草地贪夜蛾更适宜在玉米上取食为害,存在转移至小麦为害的风险,但考虑到虫源、自然温度等条件,草地贪夜蛾在小麦上暴发的风险较小。本研...     

ULTRASTRUCTURAL AND FUNCTIONAL MORPHOLOGY OF EGGSHELLS SUPPORTS THE IDEA THAT DINOSAUR EGGS WERE INCUBATED BURIED IN A SUBSTRATE

Abstract:  The reproductive biology of dinosaurs is of great interest, particularly in light of the many fossil eggs assigned to this group. The ultrastructural characteristics of dinosaur eggshells are examined in order to calculate water vapour conductance, which indicates the nesting environment. Data were mainly derived from the literature but new values are also presented. Allometric analyses were carried out on a variety of shell parameters against predicted egg mass, and comparison was made with allometric equations for bird eggs. Shell thickness was generally larger than seen for extant birds. Total pore number and pores per unit area were similar to values predicted from bird eggs. Total pore area showed an isometric increase with egg mass, parallel to the relationship for birds, but the constant value was an order to magnitude higher than the bird values. Pore radius was unaffected by egg mass. Water vapour conductance showed an allometric increase with egg mass, parallel to the bird values, but for any given egg mass values for dinosaurs were an order of magnitude higher. Mass-specific water vapour conductance was unaffected by egg mass but was an order of magnitude higher than the bird values. Water vapour conductance per pore showed an allometric decrease with egg mass but again the predicted values were an order of magnitude higher than for bird eggs. The ultrastructural characteristics of dinosaur eggshells indicate that the nesting environment had to be saturated with water vapour and that dinosaur eggs had to be fully buried in a substrate. In this sense, therefore, dinosaur eggs resemble more those of modern reptiles than those of birds. As a consequence, maintenance of incubation conditions would have depended on the prevailing environment.     

Susceptibility of Nezara viridula (L.) (Hemiptera: Pentatomidae) Egg Masses of Different Sizes to Parasitism by Trissolcus basalis (Woll.) (Hymenoptera: Platygastridae) in the Field

Egg masses of Nezara viridula (L.) are commonly parasitized by Trissolcus basalis (Woll.), and we investigated the role of size of egg masses on parasitization by T. basalis. Sentinel egg masses were exposed to parasitism in the field for 6–7 days, when they were collected for evaluation of parasitoid emergence. We recorded the number of eggs per egg mass, the number of emerged hosts, and the number of empty and parasitized eggs. We calculated the proportion of attacked host egg masses (DE), the proportion of parasitized eggs per attacked egg mass (PE), and total parasitism (PI). The total number of egg masses exposed to parasitism was 330. The minimum, mean, and maximum egg mass sizes were 25, 75.2, and 111, respectively. DE and PE varied widely between different fields, and they were independent of egg mass size. In 14.2% of all parasitized egg masses, we found simultaneous emergence of T. basalis and N. viridula independently of host egg mass size. PE exhibited low variability compared with PI and DE, which were linearly related. PI and DE values from other field studies are consistent with the linear relationship, suggesting that PI is mostly related to the proportion of the DE. This also suggests that total parasitism is independent of egg mass size, of possible differences in plant species, and T. basalis density and strains.     

Trichogramma species (Hymenoptera: Trichogrammatidae) parasitoids of Lepidopteran eggs in Lara State, Venezuela

This work was conducted to determine the occurrence of Trichogramma wasp species in Lara State, Venezuela. Lepidopteran egg samples collected from various crop leaves were observed daily under laboratory conditions for emergence of Trichogramma species adult wasps. Trichogramma were also obtained from traps containing eggs from the hosts Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) and Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae). In the laboratory, specimens of Trichogramma species were mounted on microscope slides to show male genitalia and other morphological characters used for its identification. Trichogramma atopovirilia Oatman y Platner emerged from S. frugiperda eggs collected in a cornfield at La Palomera, Humocaro Alto and at El Parchal, Humocaro Bajo, Municipio Morán. T. atopovirilia also emerged from S. frugiperda eggs collected in a cornfield at Sabana Grande and from S. cerealella eggs used as traps in a pepper culture at Tintinal, Municipio Andrés Eloy Blanco. T. exiguum Pinto y Platner emerged from S. frugiperda eggs used as traps or collected in cornfield at Totumito and at La Palomera, Humocaro Alto. T. pretiosum Riley emerged from Phthorimaea operculella Zeller eggs collected on stored potatoes at Monte Carmelo, Sanare. The identification of Trichogramma species in Lara State would be useful in the development of biological control programs for lepidopteran pests.     

Comparison of eggshell porosity and estimated gas flux between the brown‐headed cowbird and two common hosts

The brown‐headed cowbird Molothrus ater is a brood‐parasite that lays eggs in nests of a wide range of host species, including the closely‐related red‐winged blackbird Agelaius phoeniceus and the dickcissel Spiza americana. Although cowbird eggs have accelerated development and hatch sooner than similar‐sized host eggs, this development takes place within a thickened eggshell that could impede gas flux to the developing embryo. We tested the hypothesis that the accelerated development of the cowbird embryo relative to hosts is enabled by an increase in eggshell porosity that allows increased fluxes of respiratory gases to and from the developing embryo. We found cowbird eggshell thickness was significantly greater than the eggshells of these two common hosts. Although the number of pores per egg was similar among all three species, the total pore area per egg in cowbirds was significantly greater than that of either host, despite having a smaller eggshell surface area than the red‐winged blackbird. Cowbird egg pore area was 1.9×larger than that of the red‐winged blackbird. Cowbird eggshells had a significantly greater gas flux than those of the red‐winged blackbird and the dickcissel. When conductance was normalized to published values of egg mass, cowbird eggs had a higher mass‐specific conductance than red‐winged blackbird or dickcissel eggs. These results are consistent with the hypothesis that the rapid development of brown‐headed cowbird embryos is facilitated by increased eggshell porosity, and that changes in eggshell porosity represent an adaptation that enables cowbird eggs to hatch earlier than equivalently‐sized host eggs.     

Effect of Prey and Predator Density on Predation of Rice Leaffolder Eggs by the Cricket Metioche vittaticollis

Cage experiments were conducted to quantify the predation rate of the cricket Metioche vittaticollis (Sta ˚l) on the eggs of rice leaffolder Marasmia patnalis Bradley. Egg predation by adult females was measured in response to changes in egg density, predator density and leaf area per cage. The number of eggs consumed per predator increased with egg density, without reaching a plateau. The predation rate decreased with increasing leaf area. The functional response could be adequately described with a linear Type I model, with the effect of leaf area included. This type of response to leaffolder egg density means that predation was not limited by prey handling time or satiation, but by the search rate. The search rate is here interpreted as the leaf area effectively searched for leaffolder eggs by a single predator in one day. Estimated search rates averaged 0.13 m 2 day -1 for M. vittaticollis females. The search rate of the predators increased with prey density, but a model describing a density dependent search rate explained only 3% of the total variation in search rate. Increasing predator density per cage led to a decrease in the per capita egg predation rate when predator density was more than two per m 2 leaf area. Interference might thus reduce the potential to enhance leaffolder egg predation by conservation or augmentation of predatory cricket populations.     

Breeding ecology and seasonal abundance of the giant water bug Appasus japonicus (Heteroptera, Belostomatidae)

Males of the giant water bug Appasus (= Diplonychus) japonicus Vuillefroy (Belostomatidae: Heteroptera) carry egg masses on their back, but little is known about the relationship between seasonal abundance and breeding ecology of the species. In the present study, therefore, a field survey based on a mark-and-recapture census was carried out at three survey points within a rice paddy area (0.3 km²) where A. japonicus forms a meta-population in northern Okayama, Japan. We investigated the body size, seasonal abundance, dispersion, egg mass size (number of eggs within one egg mass), number of egg masses and the total eggs carried on the back of each male as fundamental parameters of the population and breeding. Significant differences in egg mass size, number of egg masses, and total number of eggs that males carried was found among the survey points. The present results suggested the possibility that the differences in breeding parameters of A. japonicus were influenced by differences in environmental factors among the microhabitats. These results are discussed in conjunction with previous reports on seasonal abundance and breeding systems in Belostomatidae bugs.