应用菜粉蝶颗粒体病毒单克隆抗体对不同株病毒进行抗原分析

应用杂交瘤技术,以大菜粉蝶颗粒体病毒(pbGV)、菜粉蝶颗粒体病毒北京分离株(prGV-801)、武汉分离株(prGVw1-78)和济南分离株(prGV-J)等4株病毒为抗原,获得9株杂交瘤细胞(Fr1～9)。ELISA测定细胞培养上清抗体效价最高达8000,腹水效价最高达450000。9株杂交瘤细胞所分泌的抗体,各呈现株或组特异性,其中pr1～4分别与4个毒株起反应,pr5～8可与2～3个毒株起反应,而Pr9则与所有4个毒株均起反应。据此,认为这4个毒株有抗原性差异。不同毒株间抗原性的差异不仅存在于病毒粒子上,而且也存在于颗粒体蛋白上。讨论了昆虫病毒单克隆抗体在鉴别病毒抗原性差异,生物防治和流行病学研究中的意义。     

Sensory cell degeneration in the ontogeny of the chemosensitive sensilla in the labial palp-pit organ of the butterfly,Pieris rapae L. (Insecta,Lepidoptera)

Summary The ontogeny of the chemoreceptive sensilla in the labial palp-pit organ was studied in Pieris rapae by examining twelve successive stages between pupation and emergence of the imago, which takes a period of 160 h under the experimental conditions. Mitoses occur until 20 h after pupation. They lead to anlagen of sensilla, 91% of which are comprised of three sensory cells. However, two sensory cells degenerate in each sensillum during a period of 28 h. The same process occurs in anlagen with four sensory cells resulting in bicellular sensilla. Axons grow out only after the number of sensory cells has been reduced. Further consecutive steps in sensory cell differentiation are: (a) outgrowth of dendritic outer segment and dendrite sheath; (b) outgrowth of trichogen process and change in structure of elongating dendrite sheath; (c) deposition of cuticle and pore tubules in the pegs; (d) retraction of trichogen process; (e) increase in diameter of dendritic outer segment accompanied by increase of microtubule number and appearance of regularly spaced electron-dense bodies at tubular doublets; (f) branching of dendritic outer segment; and (g) transformation of the dendritic branches into curled lamellae and partial destruction of the dendrite sheath. The unique process of sensory cell degeneration is interpreted as an event that revokes a step towards a possible functional improvement of the labial palp-pit organ during further evolutionSupported by the Deutsche Forschungsgemeinschaft (SFB 4/G1)     

Cabbage (Brassica oleracea var. Capitata) fails to show wound-induced defence against a specialist and a generalist herbivore?

This paper presents tests of a model of wound-induced defence in herbaceous plants. Many studies have reported both chemical changes in leaves and changes in the behaviour and/or physiology of herbivores as a result of wounding leaves. These studies and others have led to the development of various models to explain wound-induced effects both in terms of plant response and herbivore behaviour. The model under test was proposed by Edwards and Wratten (1987) and predicts that wounding a plant will cause herbivores (1) to take more meals of a smaller size and/or consume less foliage overall (2) grow more slowly and (3) be more mobile. These predictions were tested in cabbage Brassica oleracea L. var. Capitata cv. Pixie with Pieris brassicae L. (Lepidoptera: Pieridae) as a herbivore specialising on cabbage, and Spodoptera littoralis Boisd. (Lepidoptera: Noctuidae) as a generalist herbivore. Both insects showed some reduction in consumption of leaves from upper parts of the plant, but no change in meal size. There were no effects on the growth or mobility of either species as a result of wounding foliage. These results are discussed in relation to the predictions of the model.     

Relationships between parasitoid host range and host defence: a comparative study of egg encapsulation in two related parasitoid species

Abstract. Parasitoid host range may proceed from traits affecting host suitability, traits affecting parasitoid foraging behaviour, or both. We tested the hypothesis that encapsulation can be used as a reliable indicator of parasitoid host range in two closely related larval endoparasitoids of Lepidoptera. Cotesia glomerata (L.) (Hymenoptera: Braconidae) is gregarious and a generalist on several species of Pieridae, whereas C. rubecula (Marshall) is solitary and specific to Pieris rapae (L.). We determined the effects of host species ( Pieris brassicae (L.), P. napi (L.) and P. rapae ) (Lepidoptera: Pieridae) and host developmental stage (early first, second and third instar) on encapsulation of parasitoid eggs. Host species and parasitoid species, as well as the resulting interaction between these two factors had significant effects on encapsulation of Cotesia eggs. Encapsulation in Pieris hosts was much lower for C. glomerata (<34%, except for second and third instar of P. rapae ) than for C. rubecula (>32%), even when the latter was parasitizing P. rapae. Encapsulation increased with the age of the larvae, although the only significant difference was for C. glomerata. Overall, P. rapae showed a stronger encapsulation reaction than P. brassicae and P. napi. Encapsulation levels of C. glomerata corresponded well to patterns of female host species and host age preference for oviposition and parasitoid larval performance. In contrast, percentages of encapsulation of C. rubecula were not consistent with host preference and host suitability. We argue that encapsulation alone is unlikely to provide a sufficient explanation for C. glomerata and C. rubecula host range.     

A new experimental approach to investigate migration in Pieris brassicae L.

Abstract.

• 1 It is possible to correlate distinct sequences of flight behaviour in caged females of the migrant butterfly Pieris brassicae with the main flight direction of released individuals of the same stock. The attempts to escape out of the cage point to the same mean direction as the flights of the released butterflies. This provides an experimental tool to investigate some unsolved questions concerning migration behaviour.
• 2 This study examines the constancy of the flight direction of a group of butterflies, the specificity of the direction in two populations of different geographical origin, and the frequently reported change in flight direction of subsequent generations.
• 3 The results indicate that the main flight direction of a tested group is very constant during 2 days of observation. Different directions have been detected in populations originating from Northern Germany and Southern France, respectively. The preferred directions are discussed as an adaptation to the geographical circumstances. Subsequent generations of the population from Northern Germany also show different directions. The spring generation flies to the north, the autumn generation in the opposite direction. This result corresponds to field observations that in P.brassicae a return flight occurs in subsequent generations of a year.

     

Interactions between the stem-mining weevils Ceutorhynchus napi Gyll. and Ceutorhynchus pallidactylus (Marsh.) (Coleoptera: Curculionidae) in oilseed rape

Abstract 1 The rape stem weevil Ceutorhynchus napi Gyll. and the cabbage stem weevil Ceutorhynchus pallidactylus (Marsh.) share the same habitat and food resource within the stems of oilseed rape, Brassica napus L. var. oleifera. Interactions occurring between these two sympatric species on this host were studied under both field and laboratory conditions. 2 The oviposition preference of C. pallidactylus and the within‐plant distribution of eggs and larvae were examined in field plots of oilseed rape. Female C. pallidactylus tended to lay their eggs in plants already infested by eggs and larvae of C. napi rather than in uninfested plants. The within‐plant distribution of the egg batches of C. pallidactylus did not differ significantly between uninfested plants and those preinfested by C. napi. Ovipositing females of C. napi and C. pallidactylus generally showed a significant preference for plants with larger stem diameter. 3 Laboratory choice tests provided further evidence for the oviposition preference of C. pallidactylus. Females laid significantly more eggs in leaves of plants that had been previously infested by C. napi than in leaves of previously uninfested plants. 4 Larvae of C. pallidactylus showed a significant shift of their feeding niche towards the stem base when feeding in individual plants attacked by both species. This possibly indicates ressource partitioning between C. pallidactylus and C. napi. The within‐plant distribution of C. napi larvae was not affected by the simultaneous attack of C. pallidactylus. 5 The size of the head capsule of full‐grown larvae of C. napi and C. pallidactylus was not significantly correlated with the diameter of the stem of their host plant or with the number of conspecific larvae within individual plants.     

Studies ontrichogramma buesi as a biocontrol agent againstPieris rapae in Egypt

Trichogramma buesi was reared in the laboratory on eggs of the Mediterranean flour moth,Anagasta kuehniella. The incubation period of the parasite's egg was 27 h at 23 °C and 22 h at 27 °C. The larval stage lasted 3.6 and 3.2 days, the pre-pupa lasted 16 and 23 h, and the pupa lasted 5.4 and 4.6 days at 23° and 27°C, respectively. The total developmental time (from egg to adult) averaged 9.2, 9.4, and 9.1 days when the parasite was reared on eggs ofPieris rapae, Spodoptera littoralis, andA. kuehniella, respectively, at 27 °C. Sex ratio inT. buesi was 1 ♂: 1 ♀ in nature and 1 ♂: 1.3 ♀ in the laboratory. The daily and total numbers or progeny produced/female were 5.1 and 98.2 adults, respectively. The parasite female, fed on honey, lived 10.7 days at 27 °C and 12.1 days at 23 °C. Percentages of parasitism byT. buesi on eggs ofP. rapae collected from cabbage fields ranged between 0 and 31.5 % in 1985 and betwcen 0 and 36.4% in 1986 during July through December. The respective figures on eggs collected from turnip fields were 16–42.2% and 12.5–32.1% during November and December.      

A game model for the daily activity schedule of the male butterfly

A game model is developed of the daily schedule of matesearching activity by male butterflies, assuming that each male maximizes his expected mating success given a limited total time for mate search. The model predicts that (1) in the early morning, no male is active even though many females are emerging; (2) at a critical time, many males suddenly become active; and (3) the male's maximum activity occurs after the peak female emergence and before the peak capture efficiency. The inverse problem is also analyzed, in which the temporal pattern of capture efficiency is estimated from the knowledge of male activity and female emergence, assuming the evolutionarily stable strategy (ESS) condition. The model is then applied to data from a cabbage white butterfly (Pieris rapae crucivora) population and predicts that (1) females remain unmated for several hours on average after emergence, and (2) the male 's capture efficiency is rather low and increases significantly with time during the morning.     

Endokrinologische Untersuchungen an dem Wirt-Parasit-System: Pieris brassicae-Apanteles glomeratus

Die von Apanteles glomeratus L. parasitierten Raupen von Pieris brassicae zeigen in Abhängigkeit des Parasitierungstermins eine deutliche Veränderung des Juvenilhormon (JH)-Titer-Verlaufs während des letzten Larvenstadiums. Dabei tritt ein steiler Anstieg des JH-Gehaltes der Wirtshämolymphe im Zusammenhang mit der Häutung der Parasitenlarven vom 1. zum 2. Larvenstadium auf. Aufgrund von Ligations-experimenten konnte nachgewiesen werden, daß die Parasitenlarven selbst für den erhöhten JH-Titer ihrer Wirtsraupen verantwortlich sind, indem sie während ihrer Häutungsphase anscheinend JH in die Wirtshämolymphe abgeben.Eine durch die Parasitierung gesteigerte Syntheseaktivität läßt sich aus den Befunden histologischer Schnitte der Corpora allata frühparasitierter Raupen nicht feststellen. Dagegen weisen die Prothoraxdrüsen parasitierter Raupen zur Mitte des letzten Stadiums eine deutlich kleinere Querschnittsfläche auf als unparasitierte Tiere. Eine dadurch im Zusammenhang mit dem erhöhten JH-Titer bestehende Beziehung zur Häutungsunfähigkeit parasitierter Pieris-Raupen am Ende des letzten Larvenstadiums wird diskutiert.

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Summary The effects of parasitism by Apanteles glomeratus on the hemolymph juvenile hormone (JH) titers of Pieris brassicae during the last larval instar were determined using the Galleria bioassay.Depending on the time of parasitization, a significant increase of the JH titer could be observed when moulting of the parasites from the first to the second larval instar occurred.As neck-ligatured, parasitized Pieris larvae showed a similar increase of the JH titer at this time, it is concluded that the parasite larvae themselves are responsible for the elevation of the titer by delivering JH during their ecdysis into the host's hemolymph.This is supported by histological results from the corpora allata of parasitized and unparasitized caterpillars at the first and third day of the last larval instar, indicating no differences in its secretory activity. The prothoracid glands of parasitized host larvae, however, appear significantly smaller than those of comparable unparasitized ones in the middle of the last instar. A reduced secretory activity at this time, which is assumed from their decreased size, combined with an elevated JH titer may explain why parasitized larvae fail to moult at the end of their larval development.

     

大菜粉蝶颗粒体病毒的研究:包含体结合的碱性蛋白酶

本文报道从新疆分离的一株大菜粉蝶(Pieris brassicae)颗粒体病毒(PbGV)包含体上结合有碱性蛋白酶.提取含酶的包含体蛋白,以酪蛋白为底物鉴定表明此酶在pH9.4有最大的酶活力,并定位于“包裹”在病毒粒子套膜外的包含体蛋白中.在高pH时分子皿为26,500的包含体蛋白被酶降解为19,500和15,600道尔顿的两个组分.Hg⁺⁺、Cu⁺⁺仅部分抑制酶活力,可被二异丙基氟磷酸(DFP)完全抑制.75℃以上加热处理可使酶失活,并大大降低病毒包含体的解离.推测此酶是影响PbGV对寄主感染率的因子之一.