Cue hierarchy for host plant selection in Pieris rapae

During oviposition, female insects utilize a wide variety of cues to find an optimal host for their offspring. These cues may be encountered simultaneously or sequentially, and females must rely on a hierarchical categorization to rank cues for optimal ovipositional choice. During alighting, cues are often encountered at different distances, which may influence hierarchical order. Cues that are observed at longer distances and are experienced first may be more influential on oviposition choice than those experienced at shorter distances. We tested the effects of two long‐distance cues, plant size and habitat structure, and two short‐distance cues, plant nitrogen level and predator presence, on Pieris rapae L. (Lepidoptera: Pieridae) oviposition choice through a series of two‐ and four‐choice tests in both greenhouse and field settings. We found that the long‐distance cues of plant size and habitat structure had the largest impact on P. rapae oviposition in laboratory and field settings, with females preferring large plants without habitat structure. Plant nitrogen level had a smaller impact on oviposition, and the presence of predators did not affect oviposition choice. However, plant size and plant nitrogen level had a synergistic relationship, with more eggs laid on large high‐nitrogen plants compared to large low‐nitrogen or small high‐nitrogen plants, suggesting that optimal cues throughout the entire searching process may be important for P. rapae in choosing a host plant.     

菜青虫感染蜡蚧轮枝菌后的组织病理变化

对感病菜青虫Pieris rapae组织切片的观察研究表明, 蜡蚧轮枝菌Verticillium lecanii主要通过昆虫的体壁侵染虫体。菜青虫各龄幼虫在体壁接菌12 h后,附着在虫体表面的孢子即可萌发。2～3龄幼虫,蜡蚧轮枝菌菌丝24 h就可穿透体壁进入血腔,48 h可见脂肪体等器官发生病变; 4～5龄幼虫,36 h菌丝才可穿透体壁,48 h可见虫体内有部分菌丝体。侵入虫体内的菌丝对寄生组织没有选择性。菌丝首先在入侵的血腔中生长,然后侵入脂肪体和肌肉,随菌丝在虫体内的增殖,中肠、马氏管、丝腺等相继被侵染。受侵的组织器管均发生明显的病变,如体壁分离,脂肪体变形、溶解,肌纤维排列松散,中肠上皮细胞脱落并出现许多空泡等。     

菜青虫不同虫态及虫龄的多酚氧化酶性质比较

初步比较了菜青虫Pieris rapae (L.)不同虫态及虫龄的多酚氧化酶(polyphenol oxidase)的性质。结果表明,不同虫态及虫龄的多酚氧化酶活力有很大的不同,其中以5龄幼虫酶活力最高,蛹酶活力最低。酶活力大小依次为： 5龄幼虫> 预蛹>4龄幼虫>3龄幼虫>蛹。以邻苯二酚为底物,研究了pH对多酚氧化酶活力的影响,结果表明酶催化底物氧化均有一个最适pH区域,不同虫态及虫龄的多酚氧化酶最适pH基本相同,其值为7.0±0.2 。不同虫态及虫龄的多酚氧化酶催化底物氧化的最适温度有很大的差异。3龄、4龄、5龄幼虫、预蛹和蛹的多酚氧化酶活力的最适温度分别为36.0±0.5℃、38.5±1.0℃、43.0±1.0℃、45.5±1.0℃和50.0±1.5℃,说明蛹期的多酚氧化酶活力的最适温度较高。进一步比较催化底物氧化反应的活化能,测得3龄、4龄、5龄幼虫、预蛹和蛹的多酚氧化酶活化能分别为：4 3.10±0.28、36.50±0.27、25.79±0.32、30.10±0.21和58.88±0.39 kJ/mol 。通过测定不同虫态及虫龄的多酚氧化酶催化邻苯二酚和L-多巴氧化反应的动力学特征参数,比较了不同虫期的酶对底物的亲和力。     

A comparative study of the egg-laying behaviour and larval development of Pieris rapae L. and P. brassicae L. on the same host plants

Summary Pieris rapae and P. brassicae feed on the same host plants and have synchronized seasons. P. brassicae, whose larvae are twice the size of P. rapae, lays eggs in clusters of 40–100 eggs whereas P. rapae lays single eggs. In this paper we examine how egg clustering may be advantageous for P. brassicae. The larval development of each species was studied, and found not to differ significantly. P. brassicae larvae were observed to migrate from their host plant after defoliating it. A comparison of the efficiency of host plant utilization by the two pierid species was undertaken by measuring the effect of larval feeding on the growth of their host plants (kale and brussel sprouts). The results show that egg clustering is advantageous for larval fitness in terms of host resource exploitation, and we suggest that P. brassicae is adapted for ovipositing on clumped vegetation, while P. rapae is selected for exploiting isolated plants.     

菜粉蝶幼虫、蛹和成虫的雌雄形态鉴别

利用体视显微镜观察、测量、记录菜粉蝶不同虫态雌雄个体间的形态特征差异。雌雄菜粉蝶幼虫、蛹和成虫均存在显著的雌雄二型特征,3龄之后雄性幼虫的第6腹节有一对肾型黑斑,雌性幼虫无此斑。雄蛹第9腹节有生殖孔和一条短纵裂缝,裂缝两侧有凹凸不平的半圆形瘤状突起;雌蛹腹部第8、9腹节分别有生殖孔和产卵孔,且两孔之间亦有一条纵裂缝。雌蝶前翅背面有一对上下排列的黑圆斑,其腹部末端外生殖器为圆筒型;雄蝶前翅背面一对黑斑相对较小,颜色较浅,尤其下斑为浅灰色,腹部末端具钳状外生殖器。本研究揭示了菜粉蝶幼虫、蛹及成虫不同虫态的雌雄二型差异,比较研究并提出了便于快速鉴别雌雄个体的典型特征和识别方法。     

Quality of light effects on immature stages and adults of Pieris rapae (L.) (Lepidoptera: Pieridae)

Larvae of Pieris rapae (L.), the imported cabbage worm, were reared to the adult stage under controlled light conditions. Spectral quality affected their development. The effect of the long wave ultraviolet light was to significantly decrease developmental time. The light source used also appeared to exert an effect on pupal colouration.     

山西不同地域菜粉蝶RAPD遗传多样性

采用RAPD技术分析了山西省菜粉蝶5个地域种群间的遗传多样性和遗传关系,用筛选出的12对引物扩增共得到143条带,其中127(88.8%)条带具有多态性,5个种群变异程度由大到小的顺序为:大同的(76.3%)＞太原的(74.7%)＞长治的(74.5%)＞代县的(73.7%)＞夏县的(70.7%).Shannon's信息指数分析结果显示大多数变异发生在种群内(73.7%).种群间的Nei's遗传距离较低(均＜0.1).用UPGMA和 Neighbor-joining做的基于RAPD标记的Nei's遗传距离的聚类图显示,各种群内的个体首先聚在一起,种群之间有一定分化,5个地域种群间较远距离的代县种群与夏县种群遗传关系最近并优先相聚.经过对试验结果的分析讨论认为:环境类型及其生态条件对山西省菜粉蝶地域种群的遗传多样性和遗传变异产生了重要的影响,其中农药的施用对菜粉蝶种群遗传结构的影响有可能是深刻的.     

Interspecific egg load assessment of host plants by Pieris rapae butterflies

Egglaying responses of Pieris rapae L. butterflies to the oviposition deterring pheromone (ODP) of Pieris brassicae L. were studied in the laboratory. Choice experiments with ODP treated leaves and control leaves revealed that females perform a strong preference to lay their eggs on the control leaves. This preference is maintained even when during the experiment the control leaf becomes covered with a large number of conspecific eggs. Choice experiments with cabbage leaves with and without P. rapae eggs seem to indicate the absence of intraspecific egg load assessment of host plants in P. rapae. The deterrent effect of the ODP of P. brassicae to P. rapae females persists for at least 8 days. Behavioural observations suggest olfactory hairs as well as gustatory hairs to be involved in the perception of the ODP but electrophysiological recordings of the various chemoreceptors are necessary to confirm this. Finally the prospects of application of this pheromone/kairomone in cabbage pest control are discussed.

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Appréciation de la charge interspécifique en oeufs sur la plante hôte par Pieris rapae

Résumé La réponse au laboratoire de P. rapae à la phéromone dissuadant la ponte (ODP) de P. brassicae a été étudiée par l'oviposition. Des expériences de choix entre des feuilles traitées à l'ODP et des témoins ont montré que les femelles préfèrent nettement les feuilles témoins. Cette préférence s'est maintenue même quand les feuilles témoins ont été recouvertes d'un grand nombre d'oeufs de P. rapae. Ceci peut indiquer l'absence chez P. rapae d'une évaluation de la charge de ses propres oeufs. L'effet dissuadant du ODP de P. brassicae sur les femelles de P. rapae persiste au moins 8 jours. Les observations comportementales suggèrent que des poils olfactifs aussi bien que des poils gustatifs sont impliqués dans la perception d'ODP mais une confirmation de cette hypothèse par enregistrements électrophysiologiques est nécessaire. Les perspectives d'utilisation de cette phéromone/kairomone dans la lutte contre les insectes du chou sont examinées.

     

The Genome of Pieris rapae Granulovirus

Pieris rapae granulovirus (PrGV) can infect and kill larvae of Pieris rapae, a worldwide and important pest of mustard family crops. The PrGV genome consists of 108,592 bp, is AT rich (66.8%), and is most structurally and organizationally similar to the Choristoneura occidentalis granulovirus genome. Of the predicted 120 open reading frames (ORFs), 32 genes specifically occurred in GVs, including four genes unique to PrGV (Pr9, Pr32, Pr53, and Pr117).     

铜铁试剂对菜青虫多酚氧化酶的抑制作用

以菜青虫Pieris rapae (L.)为试材,冰浴匀浆,4℃下6 403 ×g 离心,取上清液,经35%饱和度(NH₄)₂SO₄沉淀,Sephadex G100凝胶过滤柱层析等分离步骤,获得部分纯化的菜青虫多酚氧化酶制剂。研究不同浓度铜离子及铜铁试剂对该酶的影响,结果表明：Cu₂₊在0～0.100 mmol/L范围内对酶活力表现激活作用;浓度大于0.125 mmol/L时表现抑制作用,其IC₅₀为0.651±0.022 mmol/L;铜铁试剂对该酶抑制作用的IC₅₀为0.100±0.012 mmol/L。抑制动力学研究结果表明：铜铁试剂对该酶表现为可逆抑制效应,为竞争性抑制类型,其抑制常数K_i为0.076±0.013 mmol/L。     

2-羟基-4-甲氧基苯甲醛缩苯胺对菜青虫酚氧化酶的抑制作用

为筛选对十字花科蔬菜害虫菜青虫Pieris rapae（L.）酚氧化酶具有高抑制活性的化合物,为寻找新型害虫控制剂提供线索,采用酶标仪微量法以室内合成、筛选的高活性化合物2-羟基-4-甲氧基苯甲醛缩苯胺为抑制剂,研究了其对菜青虫酚氧化酶的抑制活性及抑制类型。结果表明,供试化合物对菜青虫酚氧化酶的抑制中浓度（IC₅₀）为0.116 mmol/L;该化合物为典型的可逆非竞争型抑制剂,抑制常数（K_i）为1.96 mmol/L。该化合物直接对靶标酚氧化酶产生作用,而不是通过影响酶结构内的铜离子来产生作用的。     

Associative learning in the ovipositional behaviour of the cabbage butterfly, Pieris rapae

ABSTRACT. When tested with familiar and novel oviposition sites, gravid female Pieris rapae (L.) tended to land on sites of the same appearance as those they had experienced 24 h earlier. This acquired preference could be reversed by subsequent e xperience. An ovipositional preference, shown by groups of insects, paralleled the landing preferences of single insects. These influences of experience were shown with intact cabbage plants of different kinds, with discs cut from the leaves of different kinds of cabbage, and with discs of blotting paper of different shades of green and blue, wetted with sinigrin solution or water. A single landing by a gravid female on paper wetted with sinigrin solution induced a landing preference for the same colour of paper in a choice test made 24 h later. Gravid females thus associated a favourable chemical stimulus of oviposition with the appearance of the acceptable site. Such learning by trial and error would facilitate host-selection from a distance. In the laboratory it induced oviposition on 'neutral' sites of the same appearance as 'host' sites.     

Temporal trends in phenology of the honey bee Apis mellifera (L.) and the small white Pieris rapae (L.) in the Iberian Peninsula (1952–2004)

Abstract.  1. The first adult appearance of two insect species, the honey bee Apis mellifera (L.) and the small white Pieris rapae (L.), was examined between 1952 and 2004 in Spain.
2. After factoring out the variability resulting from the broad geographical and topographical range of the 798 sampling localities, multiple regression models were used to detect temporal trends in phenology.
3. The best models were repeated, including spring temperature as the explanatory variable to examine the effects of climate on appearance phenology.
4. Both species showed similar temporal trends, delaying their appearance phenology until the mid-1970s and advancing it since that time.
5. The appearance times for both species were negatively related to mean temperature between February and April, with both species appearing earlier in years with warmer springs.
6. The strong dependence of appearance dates on temperature indicates that climatic fluctuations are primarily responsible for the inter-annual variability in spring appearance phenology of both species, and consequently account for the observed long-term trends.
7. This study demonstrates that insect phenology is an accurate and sensitive bioindicator of climate change.     

Natural Plant Chemicals Acting as Oviposition Deterrents on Cabbage Butterflies (Pieris btassicae (L.), P. rapae (L.) and P. napi (L.))

In several growers' reports Solatium lycopersicum, Sambucus nigra. Thymus vulgaris, Salvia officinalis, Artemisia absinthium, A. abrotanum , and Allium cepa are said to decrease the oviposition of Pieris brassicae, P. rapae and P. napi. In the present study the butterflies were fed with honey automats and reared throughout the year in artificial light in an insec-tarium. In a dual-choice chamber with a slow throughflow of air two equally sized cabbage leaves were placed on opposite sides. Significantly fewer eggs were layed on the cabbage leaf on which extracts of the mentioned plants had been applied. Ten butterflies were used in each experiment. The chemoreceptors and the chemicals involved are not identified but the inhibitory substances are surely secondary plant substances. Acceptance or rejection of secondary plant metabolics determines the complicated food relationships between plants and insects. The use of secondary plant substances for ecological control of insect pests is proposed.     

Responses of the parasitoid Cotesia rubecula to its host Pieris rapae in a flight tunnel

Responses of female Cotesia rubecula (Marshall) (Hymenoptera: Braconidae) to larval Pieris rapae (L.) (Lepidoptera: Pieridae) feeding on cabbage leaves were investigated in a flight tunnel. Latency of flight was shorter and the proportion of female wasps flying to leaves was greater when cabbage was infested with hosts. This indicated that wasps detected hosts prior to taking flight and were attracted to them. Wind speed was varied (18, 54, 100 cm/s) to examine its effect on the response of wasps to hosts. Flight was inhibited by increasing wind speed and was accompanied by less frequent but longer bouts of pointing (antennae raised and spread, facing into the wind). The accuracy of landing but not the duration of flight to the plant was affected by increasing wind speed. The results indicated that increasing wind speed will reduce the rate of parasitoid oviposition.

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Résumé Cette étude concerne les réactions des femelles de C. rubecula Marshall (Hyméno., Braconidae) aux chenilles de P. rapae (Lépido, Pieridae) alimentées sur feuilles de choux. Le tunnel fournit un flux laminaire et l'air est recyclé avec désodorisation par circulation sur un filtre de charbon de bois. La période de latence avant l'envol est plus brève et la proportion de femelles volant vers les feuilles plus élevée quand les choux sont contaminés par les chenilles. Ceci montre que les femelles détectent les hôtes avant l'envol et qu'ils les attirent. Le vent peut influer sur la libération de kairomones, sur les caractéristiques du panache d'odeurs et sur l'énergétique du vol; en conséquence, différentes vitesses de vent (18, 54, 100 cm/S) ont été utilisées pour examiner leurs effets sur la réaction des braconides. Le vol a été inhibé par une augmentation de la vitesse du vent et était accompagné par de plus longues, mais moins fréquentes poussées de pointage (antennes dressées et étendues, face au vent). La précision de l'atterrissage a été affectée par l'augmentation de la vitesse du vent, mais non la durée du vol vers la plante. Ces résultats ont montré que l'augmentation de la vitesse du vent peut réduire le taux de ponte du parasitoïde en inhibant le vol. La signification de ces résultats est discutée en relation avec la situation dans la nature.

     

Properties,synthesis, and accumulation of storage proteins in Pieris rapae L.

Two kinds of storage proteins (SP-1, SP-2) were confirmed in hemolymph and fat body of Pieris rapae during metamorphosis. Both proteins were present in high concentrations in the hemolymph during the last larval instar. Hemolymph concentrations of SP-1 and SP-2 dropped after pupation as the proteins were being deposited in fat bodies. SP-2 is present in a larger amount than SP-1. Detailed studies on storage proteins determined their properties, mode of synthesis, and accumulation in the fat body. SP-1 has a molecular weight of 500,000 and consists of one type of subunit (M_r 77,000), while SP-2 has a molecular weight of 460,000 and is composed of two types of subunits (M_r 80,000 and 69,000). The pl values of SP-1 and SP-2 were determined to be 6.97 and 7.06, respectively. Fat body cells from 1-day-old fifth instar larvae synthesized storage proteins in large amounts, whereas those from late prepupae exhibited high protein sequestration. Proteins taken up in fat body accumulated in dense granules during the pupal stage but sharply decreased at the adult stage. Morphological changes in the fat body tissues were observed during the larval-pupal transformation; the nuclei of fat body cells became irregularly shaped, and the boundaries between cells seemed to be obscure. Synthesis, storage, or degradation of storage proteins in fat body during development is closely associated with morphological changes in the tissues.     

菜青虫幼虫肠道细菌的分离及鉴定

目的为深入研究菜青虫肠道的营养生理,分析其取食消化机制,对菜青虫肠道细菌进行了研究。方法从自然种群的菜青虫肠道环境中按传统分离、纯化、培养,获得细菌5个菌株,对其茵体形态、染色反应、培养性状、生理生化反应进行了系统研究。结果鉴定结果l号菌株为李斯特菌属（Listeria）,2号菌株为皮杆菌属（Dermabacter）,3号菌株为丙酸杆菌属（Propionibacterium）,4号菌株为沙雷菌属（Serratia）,5号菌株为短状杆菌属（Brachybacterium）。结论在菜青虫肠道环境中分离出5个菌株,鉴定出分类地位。其菌株之间的数量具有明显差异,以皮杆菌属数量最多（2×10^8）,需进一步研究该菌的功能及其在菜青虫肠道中的作用。     

Behavioural evolution in the cabbage butterfly (Pieris rapae)

Summary Australian and U.K. Pieris rapae differ markedly in their oviposition behaviour; U.K. females produce a more aggregated egg distribution, and lay their eggs more quickly, than do Australian females. The adaptive reason for this divergence probably lies in the relative costs of increased flight time (more costly in the U.K.) and increased local crowding (more costly in Australia). There is also a strong relationship between juvenile developmental rate (at constant temperature) and oviposition behaviour, but the form of this relationship differed between the two populations. The adaptive reasons for the link between developmental rate and behaviour is not clear. It may be that this link represents the tip of the iceberg; i.e. that physiological, developmental, and behabioral characters all co-vary in ways and for reasons that we do not yet understand.     

Development of the parasitoid,Cotesia rubecula (Hymenoptera: Braconidae) in Pieris rapae and Pieris brassicae (Lepidoptera: Pieridae): evidence for host regulation

Several recent models examining the developmental strategies of parasitoids attacking hosts which continue feeding and growing after parasitism (=koinobiont parasitoids) assume that host quality is a non-linear function of host size at oviposition. We tested this assumption by comparing the growth and development of males of the solitary koinobiont endoparasitoid, Cotesia rubecula, in first (L1) to third (L3) larval instars of its preferred host, Pieris rapae and in a less preferred host, Pieris brassicae. Beginning 3 days after parasitism, hosts were dissected daily, and both host and parasitoid dry mass was determined. Using data on parasitoid dry mass, we measured the mean relative growth rate of C. rubecula, and compared the trajectories of larval growth of the parasitoid during the larval and pupal stages using non-linear equations. Parasitoids generally survived better, completed development faster, and grew larger in earlier than in later instars of both host species, and adult wasps emerging from P. rapae were significantly larger than wasps emerging from all corresponding instars of P. brassicae. During their early larval stages, parasitoids grew most slowly in L1 P. rapae, whereas in all other host classes of both host species growth to pupation proceeded fairly uniformly. The growth of both host species was markedly reduced after parasitism compared with controls, with the development of P. brassicae arrested at an earlier stage, and at a smaller body mass, than P. rapae. Our results suggest that C. rubecula regulates certain biochemical processes more effectively in P. rapae than in P. brassicae, in accordance with its own nutritional and physiological requirements. Furthermore, we propose that, for parasitoids such as C. rubecula, which do not consume all host tissues prior to pupation, that parasitoid size and host quality may vary independently of host size at oviposition and at larval parasitoid egression.