甘蔗、玉米气味对亚洲玉米螟成虫产卵和幼虫取食的影响

【目的】农作物间套作对害虫的影响很大程度上取决于害虫的行为反应,通过研究玉米/甘蔗套作系统中植物气味对亚洲玉米螟Ostrinia furnacalis(Guenee)行为的影响,将为利用化学生态手段防治套作田中的害虫提供依据。【方法】通过昆虫触角电位实验、成虫产卵和幼虫取食实验,测定了甘蔗、玉米植株及二氯甲烷漂洗物对亚洲玉米螟成虫产卵、幼虫取食的影响。【结果】亚洲玉米螟成虫在甘蔗植株上的落卵量(卵粒数、卵块数)与玉米植株差异不显著,取食甘蔗植株的幼虫数量显著低于玉米植株。亚洲玉米螟对甘蔗、玉米叶片漂洗物均可产生EAG反应,且在同一浓度下的反应值之间无显著差异。成虫产卵量(卵粒数、卵块数)在0.1 gE/mL浓度的甘蔗和玉米漂洗物间差异不显著;幼虫对经甘蔗叶片漂洗物处理过的饲料的相对取食率均低于65.00%,显著低于玉米漂洗物处理的饲料。【结论】甘蔗和玉米气味对亚洲玉米螟产卵的影响没有差异,但甘蔗气味会导致初孵幼虫表现出很强的逃逸行为。     

广聚萤叶甲成虫产卵行为及其产卵部位的选择性

【目的】明确广聚萤叶甲成虫产卵行为及其产卵部位的选择性。【方法】在室内条件下,对广聚萤叶甲成虫交配及产卵的系列行为、产卵场所选择、不同部位豚草植株叶片叶绿素b的含量进行了观察和测定:(1)将1对成虫放到养虫笼内的一株豚草上,观察交配时间,记录产卵数量、前后2粒卵之间的产卵时间间隔;(2)在均匀分为5部分(0～10、11～20、21～30、31～40和41～50 cm)的豚草植株上,随机放置10对成虫,观察雌虫对于产卵场所的选择。(3)将上述5个部位的豚草叶片通过丙酮匀浆法处理,用紫外分光光度计测定其在645和663 nm的吸光值,计算叶绿素b含量。【结果】广聚萤叶甲成虫完成一次成功交配平均需96.09 min。雌虫一般需45 min的时间来寻找其适应的产卵场所,在产卵过程中,成虫习惯将卵产于叶片背面,雌虫喜欢用口器来清理刚产下的卵粒。在一株50 cm高的豚草植株上,雌虫喜欢将卵产在植株中部21～30 cm和中上部31～40cm的叶片上(从下往上划分)。卵块数量和豚草不同部位叶片叶绿素b含量呈显著的正相关性。【结论】广聚萤叶甲成虫喜欢产卵在叶绿素b含量较高的叶片背面,可能以视觉识别叶片颜色来选择和定位产卵场所。     

豚草生育期和被利用状态对广聚萤叶甲产卵选择的影响

【背景】植食性昆虫对产卵场所的选择行为受多种因素的影响,其中寄主植物的发育阶段和被同种其他个体利用程度是影响其产卵选择的重要因素之一。【方法】采用野外罩笼的选择性试验,观察了广聚萤叶甲成虫对不同生长发育阶段、不同被取食程度、不同落卵量的豚草植株的产卵选择行为,分析产卵选择频次,用Cox比例风险模型拟合识别期以估计产卵选择偏好性。【结果】开花期豚草被选择产卵的风险(瞬间概率)仅为生长期的16.5%,苗期豚草被选择产卵的风险为生长期的34.1%;成虫对3种被食程度豚草的产卵选择频次之间存在显著差异(n=20,P<0.01),在3级被食程度豚草上产卵次数最多(12次),而在5级被食豚草上产卵次数最少(2次),表明成虫明显偏好将卵产于已被中等程度取食的植株上;成虫对不同落卵量植株(0、4、8个.株-1)未表现出显著的产卵偏好,对不同密度(高、低)斑块的豚草的产卵选择亦无显著差异。【结论与意义】豚草生育期和被取食程度影响广聚萤叶甲雌虫的产卵选择,而植株上的落卵量和豚草密度对产卵选择没有影响。     

梨花迁粉蝶微孢子虫对家蚕的侵染力与胚传性

【目的】对梨花迁粉蝶Catopsilia pyranthe分离的微孢子虫进行形态与分子鉴定,探究其对非天然宿主家蚕Bombyx mori的侵染力与胚传性。【方法】从田间采集的梨花迁粉蝶中分离得到梨花迁粉蝶微孢子虫液,测定其孢子的形态、大小、体积、长短轴比,同时对该孢子虫的16S r DNA进行PCR克隆测序与分析。将梨花迁粉蝶微孢子虫Nosema sp.CP与家蚕微孢子虫N.bombycis分别对2龄起蚕、4龄起蚕进行添食感染比对,测定家蚕食下两种微孢子虫的感染率和胚种传染能力。【结果】本研究分离的梨花迁粉蝶微孢子虫形态为长椭圆形,具双核;其16S r DNA序列与已报道的梨花迁粉蝶微孢子虫的序列一致性大于99%,为梨花迁粉蝶微孢子虫。梨花迁粉蝶微孢子虫和家蚕微孢子虫对家蚕综合感染率分别是68.8%和98.3%;在继代蚁蚕中,感染梨花迁粉蝶微孢子虫和家蚕微孢子虫的雌蛾所产蚕卵次代蚁蚕检出有孢子虫的检出率分别为100%和100%,卵壳的孢子虫的检出率分别为92.9%和100%;梨花迁粉蝶微孢子虫和家蚕微孢子虫对家蚕的胚种传染力分别为9.6%和23.2%。【结论】本研究分离得到的微孢子虫为梨花迁粉蝶微孢子虫,具有微孢子虫Nosema属的典型特征。梨花迁粉蝶微孢子虫能感染危害家蚕,也具有家蚕胚种传染性,但感染率和胚传率均明显低于家蚕微孢子虫,是蚕业生产中必须防控的对象。     

东北地区三代粘虫玉米田为害行为研究

【目的】研究东北地区2代粘虫Mythimna separata (Walker)成虫的产卵规律和3代粘虫幼虫的取食行为,揭示3代粘虫在东北地区玉米田的为害行为机制,为粘虫的预测预报及综合防控提供科学依据。【方法】采用罩笼法研究2代粘虫成虫的产卵节律及对不同寄主植物的产卵选择性;采用田间调查和叶碟法取食试验研究3代粘虫幼虫在田间的发生特点及其对不同寄主植物的取食选择性。【结果】(1)2代粘虫成虫在夜间20:00-23:00时间段产卵量最高,占总量88.36%,显著高于其它时间段(P<0.01)。(2)2代粘虫成虫只选择稗草进行产卵,并且在稗草上部干枯叶尖所产卵量最高,占总落卵量的81.98%,显著高于其他产卵位置(P<0.01),玉米上没有产卵。(3)2龄幼虫对稗草具有明显的取食选择性,显著高于玉米(P<0.05);3-6龄幼虫均对玉米叶片具有明显取食选择性,显著高于稗草(P<0.05)。(4)2龄幼虫对稗草和玉米之间的取食量差异不显著(P>0.05),3龄幼虫对稗草的取食量显著高于玉米(P<0.05),4-6龄幼虫对玉米的取食量显著高于稗草(P<0.05)。【结论】2代粘虫成虫的产卵习性和3代粘虫幼虫的取食选择性决定了东北地区3代粘虫在玉米田以高龄幼虫为害的特点。     

椰子木蛾的产卵节律及其对寄主植物的产卵选择性

【背景】椰子木蛾是近年来新入侵我国棕榈科植物的害虫,研究其产卵习性可为监测和防治该虫提供参考。【方法】在室内条件下,观察、记录了椰子木蛾雌成虫的产卵节律及其对不同寄主植物的产卵选择性。【结果】椰子木蛾最高日产卵量可达34.4粒·头-1,且主要集中在羽化后4 d内产卵,占总产卵量的54.1%;产卵活动主要发生在夜间23:00到次日8:00;在椰子、蒲葵、大王棕、槟榔和散尾葵等寄主植物上的产卵量无显著差异,为89.3~147.7粒·头-1,但产卵位置存在差别。【结论与意义】椰子木蛾雌成虫具有较强的繁殖能力和产卵节律性,且在不同寄主植物上的产卵量一致。     

柳毒蛾繁殖生物学的初步观察

【目的】为了明确柳毒蛾Leucoma salicis(Linnaeus)交配的日节律高峰,温度和不同交配持续时间处理对成虫寿命、产卵量和孵化率等繁殖生物学的影响。【方法】将新羽化的柳毒蛾成虫置于养虫笼中,观察交配的日节律高峰,并统计不同温度和不同交配持续时间处理下的成虫寿命、产卵量和孵化率。【结果】成虫在羽化当晚的后半夜凌晨开始交尾,次日晚上开始产卵。成虫交配集中在羽化翌日凌晨3:00—5:00之间,高峰为4:00。产卵高峰都出现在2日龄成虫,但是,25℃下成虫交配持续时间(9.2 h)显著短于28℃(11.8 h)。交配持续时间为30、60和300 min的处理,雌成虫平均寿命显著长于对照(对照9.2 h),雄虫仅60 min的处理显著长于对照。同时,极短的交配持续时间(30 min)显著降低雌虫的产卵量和孵化率。【结论】试验明确了成虫交配的日节律高峰,在适宜的温度范围内(25~28℃),雌雄成虫的寿命、单雌总产卵量无显著差异,交配持续时间明显影响成虫寿命、产卵量和卵孵化率。     

氯虫苯甲酰胺抗性小菜蛾的产卵行为和交配节律观察

【目的】为了明确氯虫苯甲酰胺抗性小菜蛾Plutella xylostella(L.)的交配节律、产卵节律和产卵部位偏好是否发生变化,以及这些行为变化是否有利于小菜蛾抗药性的形成。【方法】采用室内观察的方法,比较了小菜蛾氯虫苯甲酰胺抗性品系与室内品系在产卵行为和交配节律上的差异。【结果】(1)抗性品系在甘蓝植株上产卵时偏好选择中下部叶片,L1-L5叶上卵量占总卵量的比例,抗性品系显著高于室内品系;抗性品系在叶背面产卵的比例也高于室内品系,但差异不显著;而在心叶、叶柄和茎干部位3个品系间的产卵比例基本相当;(2)3个品系交配比例最高的时间段均在0:00—6:00,但交配比率第二高的时间段3个品系间存在差异,室内品系(29.40%)和中抗品系(25.91%)出现在18:00—24:00,而高抗品系(28.67%)出现在12:00—18:00;(3)室内品系、中抗品系和高抗品系白天产卵量占总产卵量的比例分别为39.49%、37.57%和42.67%,高抗品系白天产卵比例明显增加。但3个品系在4个时间段产卵从多到少规律一致,依次是0:00—6:00,12:00—18:00,18:00—24:00,6:00—12:00。【结论】抗性品系在甘蓝植株上产卵时,选择的部位更靠近植株的中下部,趋向于叶片背部。抗性品系和室内品系的交配节律也存在一定的差异,交配高峰期有一定程度的错开。氯虫苯甲酰胺抗性品系的这些行为变化有利于抗性基因的纵向传递,但是否影响抗性形成的速度需要进一步研究。     

三叶虫萤的交配与产卵行为

【目的】研究三叶虫萤Emeia pseudosauteri成虫的交配与产卵行为,丰富三叶虫萤的生物学研究,推动三叶虫萤的人工繁育。【方法】采用室内试验与野外观察相结合、仪器拍摄和人工观察相结合的方法研究三叶虫萤的交配与产卵行为。【结果】本文先描述了三叶虫萤成虫交配前雄雄相遇、雌雌相遇、雌雄相遇分别会发生的情况,然后较为详细地描述了交配的过程。交配姿势有上下体位(或称"∠"型)和尾对尾体位(或称"—"型),后者由前者转换而来。雌雄成虫可以多次交配,雄虫有交配干扰和假交配现象。成虫24 h内均有交配现象,交配高峰出现在20:00-22:00(交配率20.8%)和12:00-14:00(交配率15.1%)。雌虫多数喜将卵产在潮湿的苔藓上,卵常聚集成一丛或成簇排列。雌虫可多次产卵,但初次产卵数量最多(高达67.82%),随后产卵量则随产卵次数增加而减少。雌雄虫多次交配后单只雌虫的第一次产卵量[(45±5)粒]多于单次交配后单只雌虫第一次产卵量[(20±4)粒]。雌虫的产卵次数和产卵量与其体重相关,体重越重则其产卵次数和产卵量越多。【结论】三叶虫萤的交配产卵行为与以往报道的萤火虫交配产卵行为很多相似之处,但也有一些特殊行为或规律。     

影响暗黑鳃金龟成虫取食、寿命及生殖力的植物叶片营养成分分析

【目的】分析植物叶片中主要营养成分与暗黑鳃金龟Holotrichia parallela成虫取食偏好关系,明确影响其成虫取食、寿命及生殖力的主要营养成分。【方法】测定室内5种植物(花生、核桃、榆树、金叶女贞和毛白杨)叶片饲养的暗黑鳃金龟成虫寿命、取食量和产卵量,分析植物叶片中4种主要营养成分(氨基酸、脂肪酸、粗纤维和总磷)含量与暗黑鳃金龟成虫取食、寿命和生殖力之间的相关性。【结果】暗黑鳃金龟成虫对5种植物叶片的日均取食量由高到低依次为：花生>核桃>榆树>金叶女贞>毛白杨;取食核桃、花生和榆树叶片的成虫总取食量和单雌总产卵量与取食金叶女贞和毛白杨的成虫间均差异极显著(P<0.01)。成虫总取食量与植物叶片中氨基酸含量显著相关(P<0.05; r=0.515);成虫单雌总产卵量与植物叶片中脂肪酸及氨基酸含量间极显著相关(P<0.01)(分别为：r=0.698和r=0.746)。植物叶片中必需氨基酸含量与成虫取食量和产卵量相关性与植物叶片中总氨基酸含量与成虫取食量和产卵量的相关性基本一致;成虫取食量与植物叶片中赖氨酸含量最相关,而成虫单雌总产卵量与植物叶片中各种必需氨基酸含量均相关。成虫寿命与植物叶片营养成分含量不相关。【结论】植物叶片中的赖氨酸含量是影响暗黑鳃金龟成虫取食偏好的关键因子,植物叶片中必需氨基酸含量和脂肪酸含量影响暗黑鳃金龟生殖力。     

Dynamics of oviposition in Danaus plexippus (Insecta: Lepidoptera) on milkweed, Asclepias spp

Where a butterfly chooses to lay an egg will influence the subsequent survival of her offspring. In this paper we report on the effect of a number of variables which influence the choice of oviposition site in Danaus plexippus L. Experiments were conducted under both flight cage and field conditions. The field observations consisted of recording the within and between plant egg dispersions across different patch sizes. Laboratory experiments looked at egg laying preferences as affected by plant species, age and condition. Butterflies were selective in their choice of oviposition site. Eggs were laid singly on the underside of medium sized leaves towards the top of a plant. More eggs were laid per plant on single isolated plants than on plants within a patch. The number of eggs per plant increases with plant height but decreases with plant age. Females preferred young plants or plants with fresh regrowth of leaves. These characteristics could override species preferences which were, in decreasing order, Asclepias curassavica. A. fruticosa and A. physocarpa. Species preferences varied between butterflies and with female age. Neither the presence of eggs nor larvae on a plant deterred oviposition. These results are compared with previous observations of egg laying in this species.     

Helicoverpa armigera (Hübner): can wheat stubble protect cotton plants against attack?

Abstract  When investigating strategies for Helicoverpa armigera (Hübner) control, it is important to understand oviposition behaviour. Cotton ( Gossypium hirsutum ) was sown into standing wheat ( Triticum astivum L.) stubble in a closed arena to investigate the effect of stubble on H. armigera moth behaviour and oviposition. Infrared cameras were used to track moths and determine whether stubble acted as a physical barrier or provided camouflage to cotton plants, thereby reducing oviposition. Searching activity was observed to peak shortly before dawn (03:00 and 04:00 h) and remained high until just after dawn (4 h window). Moths spent more time resting on cotton plants than spiralling above them, and the least time flying across the arena. While female moths spent more time searching for cotton plants growing in wheat stubble, the difference in oviposition was not significant. As similar numbers of eggs were laid on cotton plants with stubble (3.5/plant SE ±0.87) and without stubble (2.5/plant SE ±0.91), wheat stubble does not appear to provide camouflage to cotton plants. There was no significant difference in the location of eggs deposited on cotton plants with and without stubble, although more eggs were laid on the tops of cotton leaves in wheat stubble. As the spatial and temporal distribution of eggs laid on the cotton plant is a crucial component of population stability, eggs laid on the upper side of leaves on cotton plants may be more prone to fatalities caused by environmental factors such as wind and rain. Therefore, although stubble did not influence the number of eggs laid, it did affect their distribution on the plant, which may result in increased mortality of eggs on cotton plants sown into standing wheat stubble.     

悬铃木方翅网蝽与红带网纹蓟马的竞争关系研究

【背景】悬铃木方翅网蝽是仅危害悬铃木的外来入侵物种,而红带网纹蓟马寄主广泛,可吸食悬铃木叶片汁液,2个物种客观上发生了竞争关系。【方法】以悬铃木方翅网蝽与红带网纹蓟马共同发生的悬铃木种植街区为研究地点,每10d调查15根悬铃木枝条,记录各枝条各叶片上2个物种的数量,进而评价悬铃木方翅网蝽入侵对红带网纹蓟马的竞争排斥能力。【结果】悬铃木方翅网蝽在整个调查期间的种群数量明显高于红带网纹蓟马;悬铃木方翅网蝽在悬铃木上的时间生态位宽度和重叠指数均大于红带网纹蓟马,两者的时间生态位竞争系数达0.7022,明显高于对悬铃木枝条和叶片的竞争强度;悬铃木方翅网蝽和红带网纹蓟马对悬铃木枝条和叶片的竞争强度较低,且具有阶段性,空间竞争主要发生在6月中旬至7月下旬的2个种群发生高峰期;悬铃木方翅网蝽与红带网纹蓟马在悬铃木上的繁殖生态位出现了明显的时间分化,红带网纹蓟马仅秋季世代产卵于悬铃木叶片上,而悬铃木方翅网蝽所有世代均产卵于悬铃木叶上,但2个物种在悬铃木上共同繁殖期间,红带网纹蓟马选择产卵的枝条和叶片均有悬铃木方翅网蝽产卵,表明2个物种对产卵枝条和叶片具有相似的空间需求。【结论与意义】悬铃木方翅网蝽与红带网纹蓟马在悬铃木上整体的时空生态位竞争强度较弱,且2个物种的营养生态位差异较大;悬铃木方翅网蝽的入侵对红带网纹蓟马的生存和种群发展无明显影响。     

落叶松尺蠖Erannis ankeraria Staudinger的生物学特性

【目的】明确落叶松尺蠖Erannis ankeraria Staudinger的发生规律及生物学特性。【方法】野外调查和室内饲养。【结果】在集宁市落叶松尺蠖1年1代,以卵越冬,越冬卵在翌年4月下旬、5月上旬孵化,6月中下旬开始入土化蛹,成虫于9月初羽化、产卵。在温度为20℃,RH=70%的条件下,落叶松尺蠖幼虫期(19.96±0.86)d,预蛹期(3.93±0.95)d,蛹期(108.4±13.17)d。蛹分布于树干基部30~90cm范围内,深度4~8 cm。雄虫在6:00—8:00及12:00—16:00羽化,早于雌性,雌虫在20:00—24:00羽化,羽化若干小时后可交尾,交配持续时间20~260 min,可多次交尾。20℃下交尾雌虫寿命为(5.56±1.47)d,雄虫为(3.95±0.95)d,产卵量为(162.2±69.9)粒;不交尾雌性为(8.03±2.90)d,雄性为(4.38±1.59)d,产卵量为(164.1±81.3)粒,但卵不能孵化;15℃条件下不交尾雌雄寿命分别为(14.48±6.67)d,(6.64±1.76)d,产卵量为(145.7±76.8)粒。【结论】落叶松尺蠖危害期短,蛹期较长,雌雄成虫羽化时间有差异;温度和交尾对寿命和产卵量都有显著影响。     

Temporal changes in olfactory and oviposition responses of the diamondback moth to herbivore‐induced host plants

Temporal changes in the pre‐ and post‐alighting responses of mated female diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), to two species of Brassica (Brassicaceae) host plants induced by larval feeding were studied using olfactometer and oviposition assays. Females displayed strong olfactory and oviposition preferences for herbivore‐induced common cabbage (Brassica oleracea var. capitata L. cv. sugarloaf) plants over intact plants; these preferences decreased with time and disappeared by the 7th day after induction. In herbivore‐induced common cabbage plants, eggs were clustered near feeding damage on the younger leaves (leaves 5–7), whereas in intact plants, eggs were clustered on the stem and lower leaves (leaves 1–4) . However, as the time interval between larval feeding and oviposition increased, more eggs were laid on the lower leaves of induced plants. This demonstrates a change in egg distribution from the pattern associated with induced plants to that associated with intact plants. In contrast, females displayed strong olfactory and oviposition preferences for intact Chinese cabbage [Brassica rapa ssp. pekinensis (Lour.) Hanelt cv. Wombok] plants over induced plants; these preferences decreased with time and disappeared by the 5th day after induction. More eggs were laid on the upper leaves (leaves 4–6) than on the lower leaves (leaves 1–3) of intact Chinese cabbage plants at first, but the distribution changed over time until there were no significant differences in the egg count between upper and lower leaves by the 4th day post induction. For both host plant species, pre‐alighting responses of moths were reliable indicators of post‐alighting responses on the first 2 days post induction. The results suggest that temporal changes in a plant's profile (chemical or otherwise) following herbivory may influence attractiveness to an insect herbivore and be accompanied by changes in olfactory and oviposition preferences.     

Conserving a wetland butterfly: quantifying early lifestage survival through seasonal flooding, adult nectar, and habitat preference

Conservation of once thought extinct populations of Lycaena xanthoides in western Oregon will require specific information of how the butterfly interacts with its now rare wetland habitat. Three experiments were conducted to yield information directly applicable to wetland restoration work: (1) to quantify the survival of L. xanthoides eggs laid on inundated plants, (2) to quantify adult nectar preferences, (3) to investigate the role of adult resources and how butterflies assess habitat quality. Survival of eggs laid on inundated plants was nearly seven times lower than the survival of eggs laid on uninundated plants, indicating that eggs laid on plants that are seasonally flooded are a population sink. Adult L. xanthoides preferred an endemic native nectar plant, Grindelia integrifolia × nana, as an adult resource and used it approximately 88% of the time while other butterfly species preferred to nectar on the non-native Mentha pulegium. Adult L. xanthoides had a significantly greater short-term recapture rate in two restored study sites that had a high relative amount of Grindelia integrifolia × nana compared to a degraded site that lacked the preferred nectar source. Based on the results from the three small experiments, restoration of wetlands for L. xanthoides should concentrate plantings of host plant in non-flooded areas and propagate conspicuous patches of the preferred nectar plant.     

Diamondback moth egg susceptibility to rainfall: effects of host plant and oviposition behavior

Oviposition patterns of the diamondback moth (DBM), Plutella xylostella L. (Lepidoptera: Plutellidae), differ between common cabbage (Brassica oleracea L. var. capitata) and Chinese cabbage (Brassica rapa L. var. pekinensis) (Brassicaceae) host plants. This study shows that the moth prefers to oviposit on adaxial rather than abaxial leaf surfaces and petioles of both host plants. More eggs were laid in leaf veins than on leaf laminas of both host plants, especially in Chinese cabbage, where 94.6% of eggs were laid in veins. On Chinese cabbage, very few eggs were laid in clusters (≥2 eggs), whereas on common cabbage approximately 30% of eggs were laid in groups of 2 or more eggs. Removal of wax from common cabbage leaves dramatically increased the number of eggs laid singly on the leaf lamina of treated plants, suggesting that leaf waxes affect how eggs are distributed by ovipositing DBM. Eggs were most susceptible to removal by rainfall from the plant surface immediately (<1 h) after oviposition and when close to hatching (>72h old) whereas they were least susceptible 24 h after oviposition. Eggs laid on common cabbage plants were more susceptible to simulated rainfall than eggs laid on Chinese cabbage plants. On common cabbage plants, egg susceptibility to rainfall on different plant parts ranked adaxial leaf surfaces>petioles = abaxial leaf surfaces>stem, but there was no difference in egg susceptibility to rainfall on the various plant parts of Chinese cabbage. Furthermore, on common cabbage plants, eggs laid on both adaxial and abaxial leaf surfaces were afforded significant protection from the effects of rainfall by leaves higher in the plant canopy. On common cabbage plants, oviposition patterns reduce the potential impact of rainfall on eggs, possibly reducing the effect of this important abiotic mortality factor in the field.     

甘肃省苹果蠹蛾卵的空间分布格局

为准确掌握苹果蠹蛾Cydia pomonella(L.)的田间发生动态,本文对苹果园中苹果蠹蛾卵的空间分布格局和抽样技术进行了研究。结果表明:在第2代卵发生高峰期,苹果叶片上的苹果蠹蛾卵量显著高于果实上的卵量(叶片上着卵量占总卵量的58.2%,P<0.05),叶片上的卵主要分布于叶片正面(正面着卵量占叶片上总卵量的69.6%,P<0.05);在树冠不同方位上,东、南两面的着卵量最大,但在不同空间层次上分布的卵量没有差异。卵在叶片和果实上均呈聚集分布,且聚集强度随种群密度的升高而增加,其聚集是由环境因素造成的。文中还根据Taylor幂法则参数建立了苹果蠹蛾卵的理论抽样数模型。