桔小实蝇雌成虫对寄主挥发物β-石竹烯的行为反应

寄主植物挥发性化合物往往对昆虫产卵场所的选择具有重要的影响,为了明确桔小实蝇Bactrocera dorsalis众多寄主中是否存在特定的挥发物能够引诱桔小实蝇雌成虫产卵,本研究对桔小实蝇3种寄主(番石榴、橙子和芒果)果实的挥发物进行了鉴定,并测试了相关挥发物对桔小实蝇产卵行为的影响.研究结果表明3种寄主果实均能引诱桔小实蝇产卵并且β-石竹烯是3种寄主果实中共有的挥发物;Y型嗅觉仪和四臂嗅觉仪测试均表明低浓度β-石竹烯(9 μg/mL)对桔小实蝇雌成虫具有引诱作用,但高浓度β-石竹烯对桔小实蝇没有引诱作用;增加寄主番石榴果实中β-石竹烯的含量也会显著降低果实对雌虫产卵的诱集效果.本研究证实了特定浓度的β-石竹烯在桔小实蝇产卵行为中的作用,为开发该虫防治中的推拉策略提供了一种思路.     

甜菜夜蛾对不同寄主植物的产卵和取食选择

为了探讨甜菜夜蛾Spodoptera exigua对不同寄主植物的产卵选择及成虫产卵选择与幼虫取食选择间的关联度, 本研究选取玉米、豇豆、甘蓝、黄瓜、棉花、辣椒和番茄7种植物进行了选择性和非选择性实验研究, 并采用Y型嗅觉仪测定了成虫对其中3种寄主植物及其挥发物抽提物的趋性。结果表明：在田间非选择性实验中, 甜菜夜蛾在不同寄主植物上的落卵量依次为：玉米>辣椒>棉花>黄瓜、豇豆、番茄>甘蓝。Y型嗅觉仪的行为测定表明, 雌成虫对玉米及其挥发物抽提物的趋性最强, 黄瓜次之, 对甘蓝的趋性最弱, 这与雌虫的产卵选择性一致。不同龄期甜菜夜蛾幼虫对寄主植物的取食选择性有所不同, 且随观测时间的延长有所改变;低龄幼虫对豇豆、玉米和黄瓜的选择性较强, 对甘蓝、番茄、辣椒和棉花的取食选择性则较弱, 高龄幼虫对辣椒也具有较强的选择性;5龄幼虫对寄主植物的选择性不如低龄幼虫明显。结果显示, 甜菜夜蛾对不同寄主植物的产卵选择性显著不同, 植物抽提物在雌成虫的产卵选择中具有重要作用, 甜菜夜蛾对寄主植物的产卵选择性和幼虫取食选择性并不一致。     

多种植物挥发物及马铃薯甲虫聚集素对马铃薯甲虫的引诱作用

马铃薯甲虫Leptinotarsa decemlineata (Say)是马铃薯上一种最主要的毁灭性害虫。由于其严重的抗药性, 急需寻找一种替代杀虫剂的防治方法。本实验从开发马铃薯甲虫引诱剂的目的出发,用“Y”型嗅觉仪测定了马铃薯甲虫对来自植物的7种挥发物单体、8个挥发物混合物配方以及马铃薯甲虫聚集素的行为反应,并进一步进行了田间诱集试验。室内生测结果表明,2-苯乙醇对马铃薯甲虫雌雄虫都有明显的引诱作用。芳樟醇+水杨酸甲酯+顺乙酸-3-己烯酯的混合物对马铃薯甲虫雄虫有很强的引诱作用(81.67%), 但是对雌虫引诱作用不明显(63.33%)。在其中加入马铃薯甲虫聚集素不但提高了对雄虫的引诱率（88.33%）,还消除了之前的雌雄性别间反应差异现象,使对雌虫的引诱率达到了83.33%。田间诱集结果显示,芳樟醇+水杨酸甲酯+顺乙酸-3-己烯酯+马铃薯甲虫聚集素在所研究的引诱剂配方中引诱效果最好。从而为马铃薯甲虫发生的预测预报和诱杀技术提供了研究基础。     

缓释单萜类挥发物对落叶松毛虫行为及落叶松主要防御蛋白的影响

单萜类植物挥发物能够影响昆虫行为,为了延长其作用时间并初步测定特定单一的单萜类挥发物是否为生物间的信号物质,选取落叶松挥发物α-蒎烯、月桂烯和莰烯,进行缓释处理后施用于兴安落叶松(Larix gmelinii)苗木并进行生测。将3种挥发物倒入缓释瓶中,挂于2年生落叶松苗木中下部;以用3种挥发物直接喷施落叶松苗为对照。通过室内Y形管嗅觉仪和室外苗木罩笼产卵试验,测定不同处理的落叶松苗对落叶松毛虫(Dendrolimus superans)雌成虫产卵寄主选择行为的影响。测定落叶松针叶内与抗虫相关的几种主要防御蛋白的活力。Y管嗅觉仪测定结果显示,用α-蒎烯和月桂烯喷施及缓释处理的落叶松对雌成虫有显著引诱作用;缓释处理的效果可持续5d;施用莰烯有显著驱避作用,缓释处理的效果可持续4d。室外笼罩试验结果表明,在分别施用α-蒎烯或月桂烯的树苗上,落叶松毛虫雌虫产卵量显著高于对照,缓释处理的效果可持续3d;施用莰烯的树苗上,落叶松毛虫雌虫产卵量显著低于对照,缓释处理的效果可持续3d。表明挥发物装于缓释瓶内与挥发物具有相同的作用效果,并可以有效延长挥发物的作用时间。各处理落叶松针叶内POD、CAT、PAL、PPO、CI和TI的活性均无显著变化,说明这3种单萜类挥发物不是兴安落叶松的预警信号物质,单一施用不能系统诱导增强落叶松的抗虫性,只起到落叶松毛虫行为干扰剂的作用。     

韭菜迟眼蕈蚊对几种植物的产卵和取食选择性研究

为了探究韭菜迟眼蕈蚊对不同植物的选择性,本文通过室内控制实验和Y型嗅觉仪实验研究了韭菜迟眼蕈蚊成虫和3龄幼虫对7种植物的产卵和取食选择性行为。结果发现,韭菜迟眼蕈蚊对韭菜的产卵和取食选择性最高,成虫落卵数量221.67粒/盒,雌雄虫的选择系数分别为0.30和0.20,幼虫取食选择率为33.50%;对茴香和朝天椒的选择性最低,成虫落卵数量分别为81.00和23.00粒/盒,雌雄虫的选择系数分别为-0.27、-0.48和-0.27、-0.39,幼虫取食选择率分别为5%和0%。田间推荐韭菜与茴香或朝天椒间作。     

信息化合物在平腹小蜂寄主选择过程中的作用

利用“Y”型嗅觉仪研究了平腹小蜂对不同荔枝品种的离体叶片、活体植株、叶片挥发油和挥发物单个组分以及对荔枝蝽不同处理的的选择行为反应.结果表明,三月红和淮枝品种对平腹小蜂的引诱效果较好,而糯米糍、桂味、妃子笑和黑叶品种的作用不明显.作为荔枝叶片的主要挥发物组分,α-蛇麻烯和β-子丁香烯对平腹小蜂的引诱效果也不明显,但两者在天敌搜索寄主过程中表现为协同作用,并且当均以0.3 μl·μl^-1的浓度混合后,引诱效果最好.双向选择试验表明,平腹小蜂对荔枝蝽卵没有明显的趋性,而对荔枝蝽雌成虫及成虫腹末的水提液趋性较强.培养皿生测试验则表明,平腹小蜂在荔枝蝽卵样点处作出选择行为的数量和滞留次数最多,对荔枝蝽卵有较高的选择性.荔枝蝽成虫挥发物的主要组分(E)-2-己烯醛对平腹小蜂没有显著的引诱作用.     

草地螟阿格姬蜂生物学特性初步研究

草地螟阿格姬蜂Agrypon flexorius Thunberg是草地螟Loxostege sticticalis L.老龄幼虫的优势寄生蜂,国内外对其研究报道较少。通过田间调查和室内试验,结果表明:雌雄蜂形态相似,雌蜂个体比雄峰略大。23℃下,草地螟阿格姬蜂经卵、幼虫、蛹发育到成虫,一个世代历期为30³7 d。田间寄生率为3.04%,自然平均雌雄性比为3.97∶1。羽化在寄主成虫出现一周后开始,第5天达到高峰。交尾时间一般537 d。田间寄生率为3.04%,自然平均雌雄性比为3.97∶1。羽化在寄主成虫出现一周后开始,第5天达到高峰。交尾时间一般5¹0 min。产卵时间一般为110 min。产卵时间一般为1²min,卵多产在草地螟头、胸部两侧。草地螟阿格姬蜂大多进行两性生殖,少数进行孤雌生殖。在雌蜂不产卵情况下,补充各种营养的成蜂寿命均在16℃时最长;22℃,补充蔗糖,雌蜂寿命平均为17.11 d。在雌蜂产卵情况下,20%蜂蜜水最适合繁殖。草地螟阿格姬蜂在草地螟4龄幼虫的寄生率最高,平均为40.23%。     

桑天牛卵长尾啮小蜂的寄主选择定位行为

本文对桑天牛卵长尾啮小蜂Aprostocetus prolixus LaSalle et Huang的寄主选择定位行为进行了系统研究。已有研究表明,寄主植物-寄主昆虫复合体释放的挥发物对寄生蜂有显著的引诱作用。为了查明寄主植物 寄主昆虫复合体中挥发性引诱物质的来源,对不同处理桑枝（正常桑枝、机械损伤桑枝、系统枝、桑天牛Apriona germari（Hope）咬食和产卵桑枝）、桑天牛虫粪及雌雄两性桑天牛所释放的挥发物分别进行了测定。结果显示：不同处理桑枝对寄生蜂都具有显著的引诱作用,而且产卵桑枝的引诱活性最大;桑天牛虫粪的气味对寄生蜂有引诱活性,而雌、雄桑天牛体表挥发物对寄生蜂的引诱效果不明显。桑天牛爬行痕迹对寄生蜂的微栖境接受行为没有影响,而桑天牛虫粪中的信息物质在寄生蜂的微栖境接受过程中起着重要作用。寄生蜂对产卵桑枝段的选择几率明显高于正常桑枝段和咬食桑枝段,而对不同植物上产卵刻槽的选择没有差异; 刻槽表面存在着与此卵寄生蜂寄主识别相关的信息物质。     

烟粉虱对不同寄主植物的选择性和适应性测试

为了明确在田间烟粉虱Bemisia tabaci(Gennadius)对不同寄主植物选择性和适应性,本实验在室内用Y型嗅觉仪测定了烟粉虱对13种寄主植物的选择性,随后对田间随机排列种植的这13种寄主植物依照测试结果由强到弱依次拔除(拔除次序为茄子、番茄、黄瓜、辣椒、棉花、茼麻、西葫芦、油菜、花菜、小青菜、莲花白、胡萝卜和苦瓜),每次拔除间隔时间为5 d,结果显示:田间第一次调查的结果与室内选择性测试结果一致;随着最适宜寄主的拔除,烟粉虱成虫数量在与其引诱力相近的一种或几种寄主上的略有增加,而其它植物上却没有大的变化,这表明随着最适宜寄主的拔除,烟粉虱成虫会重新分布,但趋向分布于引诱力相对较强的寄主植物;随着寄主植物的拔除,烟粉虱卵、若虫和蛹在引诱力较强的植株上均有所增加;但西葫芦拔除之后其余植株上烟粉虱卵、若虫和蛹的数量没有明显变化;小青菜拔除后,其余植株上烟粉虱卵、若虫和蛹的数量又有所增加。这表明随着最佳寄主的拔除,烟粉虱会趋向选择于引诱力相对较强的寄主植物产卵,当烟粉虱从嗜好性强的植物转移到嗜好性弱的植物时,产卵适应会滞后于取食适应。但整个实验过程中苦瓜上的烟粉虱上成虫、卵、若虫和蛹的数量均变化不大,苦瓜上的成虫应属偶然分布其上,烟粉虱成虫并不取食苦瓜,苦瓜对烟粉虱有趋避作用。本实验模拟田间种植模式,因此实验结果对田间种植具有指导意义。     

番石榴果肉挥发物化学组成及对桔小实蝇产卵行为的影响

本文研究了番石榴果肉挥发物化学组成及对桔小实蝇产卵行为的影响.通过气相色谱与质谱联用对番石榴果肉挥发物进行了分析,并比较了番石榴果肉挥发物和不同引诱物对桔小实蝇成虫诱集虫口数和产卵量的差异.化学组成分析结果表明,检出的番石榴果肉挥发物共18种化合物,含量最高的为乙酸叶醇酯,占40.07％,其次为石竹烯,占23.55％.桔小实蝇成虫产卵行为生测结果表明,番石榴果肉对桔小实蝇的引诱效果显著高于蔗糖、清水对照和空白对照,但低于水解蛋白.番石榴果肉和水解蛋白具有诱集桔小实蝇产卵的作用,桔小实蝇在番石榴果肉和水解蛋白两个处理上24 h产卵量分别为6.80±0.23和7.07 ±0.16粒/管,显著高于桔小实蝇在其它处理上的产卵量.桔小实蝇的产卵量随番石榴果肉重量增加而增加,当番石榴果肉增加至11g时,桔小实蝇的产卵量达最大值46.32±0.35粒/管.     

伞裙追寄蝇和双斑截尾寄蝇对草地螟的寄生特性

为认识寄生蝇对草地螟Loxostege sticticalis L.的寄生特性,调查了河北康保田间两种寄生蝇——伞裙追寄蝇Exorista civilis Rondani和双斑截尾寄蝇Nemorilla maculosa Meigen对草地螟各龄幼虫的寄生率、寄生部位及着卵量,并通过室内饲养对寄生蝇的存活率与寄主龄期、着卵部位及着卵量的关系进行了研究。结果表明： 两种寄生蝇在田间主要寄生草地螟5龄幼虫;寄生蝇可在每头寄主幼虫上着1～8粒卵不等,其中以1粒的居多（45.3%）,2粒的次之（33.6%）,但1头寄主幼虫中仅能羽化出1头寄生蝇;寄生蝇以寄生寄主幼虫头部和胸部较多,腹部较少,并且以寄生侧面居多,背面次之,腹面最少。寄生蝇的存活与寄主幼虫着卵量之间呈相关关系,在着卵量为1粒的寄主幼虫中,寄生蝇的存活率仅为66.7%,在着卵量为2粒及以上的寄主幼虫中,单头幼虫羽化出寄生蝇的比例为100%。     

Oviposition Choice of Two Fall Armyworm (Lepidoptera: Noctuidae) Host Strains

Fall armyworm, Spodoptera frugiperda (J. E. Smith), is a noctuid species that is composed of two morphologically identical sympatric host strains (corn and rice) that differ in their distribution among plant hosts. In an effort to explain observations of host fidelity in the field, ovipositional preference of the two strains on corn (Zea mays L.) or pasture grass (Cynodon nlemfuensis Vanderyst var. nlemfuensis) was determined using two greenhouse bioassays. In the first bioassay, corn strain females placed more eggmasses on the screen enclosure than on corn plants while grass plants contained an intermediate number of eggmasses. Rice strain females placed most of their eggmasses on grass plants. In the second bioassay, corn strain females placed an equal number of eggmasses on corn and grass plants in comparison to rice strain females which placed >3.5× more eggmasses on grass plants than on corn plants. Individual eggs as part of the eggmasses were also counted on plants and on the screen enclosure. Corn strain females equally placed eggs on the two host plants and on the screen enclosures, however rice strain females placed more eggs on grass plants compared to corn plants or the screen enclosure. This is the first report of consistent differential oviposition between corn and rice strain fall armyworm females.     

Searching and oviposition behavior of a mymarid egg parasitoid, Anagrus nigriventris, on five host plant species of its leafhopper host, Circulifer tenellus

Searching and oviposition behavior and parasitization ability of Anagrus nigriventris Girault (Hymenoptera: Mymaridae), an egg parasitoid of beet leafhopper, Circulifer tenellus (Baker) (Homoptera: Cicadellidae), were examined on five host plant species of beet leafhopper: sugar beet (Beta vulgaris L.), red stem filaree (Erodium cicutarium[L.]), peppergrass (Lepidium nitidum Nuttall), desert plantain (Plantago ovata Forsskal), and London rocket (Sisymbrium irio L.). Beet leafhopper embeds its eggs in the tissues of these plant species. For each plant species, A. nigriventris behavior was examined on plants with and without beet leafhopper eggs. Experimental design was a 5 (plant species) by 2 (host eggs present/absent) factorial. Additionally within each treatment, parasitoid behavior was observed over a 22-h period at five different observation periods: t=0, 3, 6, 9, and 22 h where t=0 h represents initial exposure of the insect with the plant. The behavioral events observed were: `fast walking' (general searching), `slow walking' (intensive searching), ovipositor probing, grooming, feeding, and resting. Significant differences (=0.05) among plant species in time spent on the plant, percentage of host eggs parasitized, and behavioral variables associated with intensive searching and oviposition all indicated that the plant species fell into two groups: `preferred' plants (sugar beet, London rocket, and peppergrass), and `unpreferred' plants (filaree and plantago). These variables also indicated that the parasitoids spent more time on, searched more, probed more, and oviposited more in plants with host eggs than plants without host eggs. Consistent effects of time (over the observation periods from t=0 to t=22 h) generally were detected only in the preferred plant species that had host eggs present. In these cases, intensive searching and probing decreased as time advanced, while variables related to general searching (`fast walking') and abandoning host egg patches (leaving the plant) tended to increase over time.     

The effect of different host plants on the reproduction and longevity of Nysius natalensis

Nysius natalensis Evans (Hemiptera: Orsillidae) is a pest of sunflower in South Africa. Adults invade sunflower fields from their weedy hosts which occur inside crop fields and on surrounding headlands. The host plant suitability for survival and reproduction as well as the effect of within‐generation host switching was studied on different wild host plants and sunflower. Life history parameters used to assess host plant suitability were F₁ adult survival, pre‐oviposition period, fecundity, and longevity. Nymphs and adults were provided with stems and seeds of five host plants, viz., Amaranthus hybridus L. (Amaranthaceae), Portulaca oleracea L. (Portulacaceae), Chenopodium album L. (Chenopodiaceae), Conyza albida Spreng. (Asteraceae), and sunflower, Helianthus annuus L. (Asteraceae). Nymphs were reared on crushed seed of the five plant species. After completion of the nymphal stage, emerging adults of each host plant group were provided with seed of a different host plant species for food. Adults did not survive long on stems only and very few eggs were laid. Seeds of the host plant species were shown to be an essential source of nutrients for N. natalensis reproduction, whereas the vegetative plant parts were unsuitable. Nymphal food and host‐plant switching between the nymphal and adult stages significantly affected the pre‐oviposition period. Nymphal and adult food source also affected female longevity. The number of eggs laid was not influenced by nymphal food, but was influenced by adult food and the switch between nymphal and adult food. The comparative attractiveness of sunflower and wild host plants for oviposition was also investigated and showed that females preferred to lay eggs on wild host plants, compared with sunflower. These results may explain why N. natalensis will lay their eggs on sunflower after weeds in the vicinity are controlled, or senesce toward the end of the growing season.     

Host plant affects pollen beetle (Meligethes aeneus) egg size

Abstract. In some herbivorous insect species, egg size is larger on low‐quality hosts than on high‐quality hosts and may be related to the prospect that larger offspring are more likely to survive on a poor host. Sizes of eggs laid by pollen beetles [Meligethes aeneus Fab. (Coleoptera: Nitidulidae)] were examined with insects confined on one of two different host plants that had previously shown differences in adult preference and larval performance. Individual females were also exposed sequentially to both the low‐quality host (Sinapis alba L.) and the high‐quality host (Brassica napus L.) and the size of their eggs was determined. Pollen beetles laid shorter eggs on low‐quality hosts both for different females on different host plants and for the same individuals on different host plants, in contrast to the prediction that low‐quality hosts would receive larger eggs than high‐quality hosts. Previously, egg production rate was shown to be reduced when pollen beetles are exposed to low‐quality hosts and it is suggested that oogenesis is incomplete, resulting in shorter eggs. The possibility that this is related to antibiosis on S. alba is discussed.     

The influence of clutch size on survival and reproductive potential of Hessian fly

The clutch size laid by Hessian flies (Mayetiola destructor Say) (Diptera: Cecidomyiidae) was manipulated over a range of 1 to 30 eggs on single wheat plants (Triticum aestivum, L.). Pupae developing from egg clutches were removed from plants, counted and reared through to adult eclosion. Wing lengths of adult males and females were recorded and used as an indicator of body size. Survival to pupal and adult stages, as well as mean wing length of resulting males and females, decreased as clutch size increased. Wing length of females from clutches showed a positive linear relationship with potential fecundity. The benefits of small clutches for a female Hessian fly's offspring are discussed in the context of the foraging behaviour of the ovipositing female. We predict that under high probabilities of survival and availability of host plants, females will lay smaller-sized clutches per plant. However when the probability of survival is low and host plants scare, the female will respond by laying larger-sized clutches.     

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.     

甜菜夜蛾在四种寄主植物上的生命表参数比较研究

在控制条件下对甜菜夜蛾Spodoptera exigua(Hübner)在白菜、大葱、甘蓝和豇豆上的生命表参数进行了比较研究。结果表明,甜菜夜蛾幼虫在4种寄主植物上均为5个龄期。幼虫和蛹在大葱上的发育历期最长,在白菜上最短。甘蓝叶片饲养的甜菜夜蛾生殖力最高,单雌产卵量为1015.8粒,豇豆叶片上饲养的生殖力最低,为496.1粒。甜菜夜蛾在甘蓝上的内禀增长率和净增殖率最高,分别为0.237和287.82,在大葱上最低,分别为0.172和173.90。在大葱上甜菜夜蛾幼虫存活率较低,在其他3种寄主植物上较高。甜菜夜蛾的特定年龄生殖率在甘蓝叶片上最高,第22天单雌产卵量高达453.6粒。研究结果表明,在选取的4种植物中,甘蓝是甜菜夜蛾的最适寄主。     

Prior host feeding experience influences ovipositional but not feeding preference in a polyphagous insect herbivore

Black vine weevils, Otiorhynchus sulcatus (Fabricius) (Coleoptera: Curculionidae), are globally‐distributed polyphagous pests of many horticultural crops. We investigated how adult weevils were affected by host switching and, in particular, how host plant species nutritional and defensive chemistry affected subsequent host plant species selection and oviposition. Adults were fed one of three host plant species, blackcurrant [Ribes nigrum L. (Grossulariaceae)], raspberry [Rubus idaeus L. (Rosaceae)], or strawberry [Fragaria x ananassa Duchesne (Rosaceae)], throughout their pre‐reproductive periods and then subjected to behavioral choice assays with these plants. Foliar chemistry differed significantly among the three host plant species. Compared to raspberry and strawberry foliage, blackcurrant foliage was 13% lower in nitrogen, 3% higher in carbon, and 28% higher in phenolic compounds. Initial host plant species had a significant effect on weevil mortality, with more weevils dying when previously fed blackcurrant (12%) than strawberry (3%) or raspberry (0%) regardless of subsequent host. Initial host plant species also affected oviposition, with weevils laying only ca. two eggs per week when previously fed blackcurrant, compared to those on raspberry or strawberry (ca. 11 and 15 eggs per week, respectively). When given a choice, weevils discriminated among host plant species and tended to oviposit on plants on which they had previously fed, even when the plant was nutritionally inferior for egg production and adult survival. In contrast, feeding behavior was only affected by the current host plant species. Feeding and oviposition were related to leaf chemistry only in blackcurrant, as leaf consumption was negatively correlated with foliar carbon and zinc concentrations, and positively correlated with foliar phosphorus and potassium concentrations.     

Habitat and host plant use of the Large Copper Butterfly Lycaena dispar in an urban environment

The Large Copper (Lycaena dispar) has been extensively studied due to its high conservation priority. The species has declined severely in North-West Europe, but is currently expanding in Central and North-East Europe. In this study, we investigated egg deposition patterns at three different spatial scales (site, plant, and leaf level) for L. dispar at 23 sites within the municipality of Vienna (Austria). In one season, a total of 2,457 eggs were counted on six Rumex species, of which two (R. stenophyllus, R. patientia) represent novel host plant records. Rumex crispus harboured 87.6% of all egg counts and was significantly preferred (4.4 eggs per plant) over the second-ranked R. obtusifolius for oviposition (1.1 eggs per plant). At the habitat scale, eggs were observed at all study sites. Egg numbers per site were equal across landscape zones, including stretches of waste land in urban habitats, except for lower egg numbers on meadows at the margin of the Vienna forest. Mowing was negatively related to the number of eggs found on all three studied scales. We conclude that L. dispar eggs are easier to find compared to adult butterflies, the butterfly can utilize more host plant species than what was previously known, and that mowing has a strong negative influence on the local butterfly populations. Urban wastelands provide important habitats, in which the species can sustain substantial population densities which are in comparison to those in the countryside. Conservation action should focus on applying less intensive rotational mowing, preferably involving mowing of suitable sites every 2?years.