Foraging and mate-finding in the silver Y moth, Autographa gamma (Lepidoptera: Noctuidae) under the risk of predation

Animal foraging and reproductive behaviour is influenced by other simultaneous demands such as predator avoidance. The trade-offs between these demands may depend on sex or mating experience. This study demonstrates that the olfactory-mediated foraging and mate-seeking behaviours in the silver Y moths, Autographa gamma , are affected by auditory cues mimicking their bat predators. Both males and females changed their foraging behaviour under simulated predation risk. Fewer moths reached the odour source following sound stimulation and the time to find the odour source increased by up to 250%. However, there were no significant differences between male and female ability to reach the plant odour source or the duration of the flight towards the source when stimulated with ultrasound. Hence females are not more cautious than males when observed in the same behavioural context. Risk-taking in males was independent of whether they were flying toward a flower odour or sex pheromones having equal attractive value. This indicates that the trade-off between olfactory and acoustic cues is independent the type of odour. Mated females were not as strongly affected by sound as non-mated, indicating that flower odours have a higher adaptive value for mated females, suggesting that some processes following mating experience influence the trade-off between flower odours and simulated bat sounds.     

Odour-mediated nectar foraging in the silver Y moth, Autographa gamma (Lepidoptera: Noctuidae): behavioural and electrophysiological responses to floral volatiles

Naive male and female silver Y moths, Autographa gamma (Lepidoptera: Noctuidae), were attracted in a flight tunnel assay to potted creeping thistle, Cirsium arvense (Asteraceae), butterfly-orchid, Platanthera bifolia (Orchidaceae), soapwort, Saponaria officinalis (Caryophyllaceae), greater knapweed, Centaurea scabiosa (Asteraceae), red clover, Trifolium pratense (Fabaceae), and catnip, Nepeta faasseni (Labiatae), plants with flowers. The most attractive plants were C. arvense , P. bifolia and S. officinalis that elicited 87, 78 and 65% source contacts, respectively. C. scabiosa was less attractive eliciting 43% response. T. pratense and N. faasseni showed the least attraction eliciting 28 and 26% source contacts, respectively. A cotton plant used as control, was not attractive. Floral volatiles from the investigated plant species were collected using headspace sampling technique. Samples were analysed using gas chromatography coupled with electroantennographic detection, and electrophysiologically active compounds were identified by coupled gas chromatography/mass spectrometry. Consistent electrophysiological responses were elicited by twelve compounds from headspace of C. arvense , thirteen compounds from P. bifolia , eleven compounds from S. officinalis , nine from C. scabiosa , ten from T. pratense and two from N. faasseni . Most of the active compounds were specific for one or two species, while benzyl benzoate was present in four and benzaldehyde and benzyl alcohol in three species. Floral scents of C. arvense , P. bifolia and S. officinalis , the most attractive flowers, were dominated by aromatic compounds that were not abundant in the scent of other flowers. To conclude, the results demonstrate the absence of a common denominator of odours present in flowers of different plants visited by A. gamma .     

Allocation to reproduction following experimental defoliation in Platanthera bifolia (Orchidaceae)

The roles of herbivory and pollination success in plant reproduction have frequently been examined, but interactions between these two factors have gained much less attention. In three field experiments, we examined whether artificial defoliation affects allocation to attractiveness to pollinators, pollen production, female reproductive success and subsequent growth in Platanthera bifolia L. (Rich.). We also recorded the effects of inflorescence size on these variables. We studied the effects of defoliation on reproductive success of individual flowers in three sections of inflorescence. Defoliation and inflorescence size did not have any negative effects on the proportion of opened flowers, spur length, nectar production or the weight of pollinia. However, we found that hand-pollination increased relative seed production and defoliation decreased seed set in most cases. Interactions between hand-pollination and defoliation were non-significant indicating that defoliation did not affect female reproductive success indirectly via decreased pollinator attraction. Plants with a large inflorescence produced relatively more seeds than plants with a small inflorescence only after hand-pollination. The negative effect of defoliation on relative capsule production was most clearly seen in the upper sections of the inflorescence. In addition to within season effects of leaf removal, defoliated P. bifolia plants may also have decreased lifetime fitness as a result of lower seed set within a season and because of a lower number of reproductive events due to decreased plant size (leaf area) following defoliation. Our study thus shows that defoliation by herbivores may crucially affect reproductive success of P. bifolia.     

A multivariate approach to post-pollination changes in the floral scent of Platanthera bifolia (Orchidaceae)

The effect of pollination on floral scent composition and production in the moth-pollinated orchid Platanthera bifolia was studied. A significant decrease in scent production was detected both two and five days after pollination. The proportion of wilted flowers was higher in pollinated compared to control plants after seven days. A principal component analysis (PCA) showed how pollination reduced scent production. All scent compounds were affected by pollination, even though some compounds had larger impact on the overall scent reduction. A classification of samples offered a quantitative test of the changes found in individual plants after pollination. The induced decrease in floral scent production following pollination is suggested to be of adaptive value for both plants and pollinators.     

Volatiles from the burnet moth Zygaena filipendulae (Lepidoptera) and associated flowers,and their involvement in mating communication

The burnet moth Zygaena filipendulae L. contains the cyanogenic glucosides linamarin and lotaustralin, which can be degraded to the volatiles hydrogen cyanide (HCN), acetone and 2‐butanone. Linamarin and lotaustralin are transferred from the male to female during mating and thus are considered to be involved in mating communication. Because volatile semiochemical cues play a major role in mating communication in many insect species, the emissions of HCN, acetone and 2‐butanone from Z. filipendulae are characterized in the present study, aiming to determine the interplay between the degradation products of cyanogenic glucosides and pheromones. The volatile emissions from Z. filipendulae and flowers inducing mating are measured using headspace solid‐phase micro‐extraction and gas chromatography‐mass spectrometry analysis. All Z. filipendulae life stages emit HCN, acetone and 2‐butanone. Virgin females show higher emissions than mated females, whereas mated males have higher emissions than virgin males. Hydrogen cyanide is only rarely detected in the course of male–female copulation. These observations indicate a role for the cyanogenic glucoside derived volatiles in female calling and male courtship behaviours, although not as a defence during copulation. Males rejected for mating by a female are accepted after injection of linamarin or lotaustralin, demonstrating that cyanogenic glucosides are also important for female assessment of the fitness of the male. Volatiles from flowers occupied during mate calling are also analyzed, and emissions from males and females result in the identification of novel putative pheromones for Z. filipendulae.     

Variable selection in Platanthera bifolia (Orchidaceae): phenotypic selection differed between sex functions in a drought year

We estimated selection on three morphological characters in the hermaphroditic, hawkmoth-pollinated orchid Platanthera bifolia and explored selection surfaces through male and female function. The work was carried out in northern Sweden during two flowering seasons (1994 and 1995) in one natural population and one season (1995) in another natural population. Fitness was estimated as number of pollinia removed (male function) and number of fruits produced (female function). We detected directional selection towards larger inflorescence size (flower number) through both sex functions in both populations in 1995. In 1994, with an unusually dry growing season, 78% of the individuals failed to set any fruit, and there was selection for larger inflorescences only through male function. In this year, there was selection towards longer flower spurs, which could be a direct or indirect effect of spurs being shortened by drought. The results demonstrate that selection patterns may vary temporally and spatially, and that the 'male function hypothesis' may be applicable as female function is more resource dependent than male function.     

Patterns of Genetic Diversity in Platanthera bifolia (Orchidaceae) with Respect to Life History Traits and Recent Range Expansion

For evolutionary and ecological analyses, genetic diversity at different scales needs to be studied in terms of biological properties, habitat, population size and population history. We surveyed Platanthera bifolia populations from six regions in northeastern Poland to determine the impact of the mating system and population history on genetic diversity. Based on variation at allozyme markers, genetic variation was relatively moderate (P?=?22.3%, A?=?1.48, H _O?=?0.083, F _IS?=??0.015) and similar to other Platanthera species. These parameters varied between populations (P?=?13.3%–26.6%, A?=?1.26–1.66, H _O?=?0.055–0.111, F _IS?=??0.262–0.147). The genetic diversity patterns were shaped by different proportions of facilitated selfing and/or outcrossing, resulting in positive and negative F _IS values, respectively. No relationship between inbreeding coefficient and population size, however, and no impact of apomixis on the level of genetic diversity of P. bifolia were found. The relatively low level of genetic differentiation among the investigated regions (F _CT?=?0.002, P?>?0.05) and among populations (F _ST?=?0.048, P?<?0.001), and the lack of a significant relationship between genetic and geographical distance, are discussed in the context of possible scenaria of postglacial expansion.     

谢丽思夜蛾雄性描记

谢丽思夜蛾Autographa schalisema(Hampson,1913)隶属金翅夜蛾亚科Plusiinae,迄今仅知雌虫。本文首次描记采自重庆的雄虫,拍摄了雄虫整体图和外生殖器照片。     

Helicostatins: brain-gut peptides of the moth, Helicoverpa armigera (Lepidoptera: Noctuidae)

Gene expression and immunolocalisation studies have determined that the helicostatins are brain-gut peptides in larvae of the lepidopteran, Helicoverpa armigera. Mapping of the distribution of these peptides in the nervous system and alimentary canal has provided evidence for multifunctional regulatory roles. In situ hybridisation studies have shown that the helicostatin precursor gene is expressed in neurones of the central and stomatogastric nervous systems, and endocrine cells of the midgut demonstrating that the helicostatins are true brain-gut peptides. Antisera raised against Leu-callatostatin 3 (ANRYGFGL-NH(2)), a peptide isolated from the blowfly, Calliphora vomitoria was used to map the distribution of allatostatin-like immunoreactive (Ast-ir) material in H. armigera to elucidate possible functions of the helicostatins. In situ hybridisation studies verified that the helicostatin precursor gene is expressed in neurones shown to contain Ast-ir, providing strong evidence that the Ast-ir material is helicostatins. Extensive immunoreactive axonal projections into complex regions of neuropile indicate that the helicostatins may have a neuromodulatory role in the brain and segmental ganglia of the ventral nerve cord. The presence of large amounts of immunoreactive material in axons within the corpora cardiaca (CC) and transverse nerves of the perisympathetic nervous system, two known neurohaemal organs, provides evidence for a neurohormonal role. The corpora allata (CA) were innervated only sparsely by Ast-ir axons suggesting that the CA are not a neurohaemal release site or a target. Thus, it is unlikely that the helicostatins regulate juvenile hormone (JH) biosynthesis or release. Ast-ir axons extended from the frontal ganglion through the recurrent nerve and many branches were closely associated with muscles of the foregut, stomodeal valve, and anterior midgut, implicating helicostatins in regulation of foregut motility. Ast-ir material was also present in nerves associated with muscles of the pyloric valve and rectum, and in endocrine cells of the midgut.     

Characteristics and distribution of intermediates between Platanthera bifolia and P. chlorantha (Orchidaceae) in the Nordic countries

In areas of sympatry Plantanthera bifolia (L.) L. C. Rich. and P. chlorantha (Cust.) Rchb. occasionally produce hybrids. These plants exhibit intermediate floral morphology. The present study presents the distribution, floral morphology, and general characteristics of these intermediates in the Nordic area. The most useful and reliable diagnostic characters for hybrid plants were (1) the distance between viscidia (normally about 1.4 mm), (2) the length of the caudicle of pollinia (about 0.7 mm), and (3) the presence of a distinct pedicel at the connection between caudicle and viscidium. Comparative chemical analyses of the floral fragrances are reported. Material in the principal Nordic herbaria indicated a generally low production of hybrids (0.46%) and that the main area of occurrence is SE Sweden and Alandia, Finland. Intermediates seem more frequent in provinces where P. bifolia is relatively long-spurred. Very few were recorded from Denmark and Norway (hybrids in the latter country here reported for the first time). Aggregations of intermediates displaying patterns of introgressive hybridization were found only on Öland and Gotland. Occurrence of hybrids outside the Nordic area is also discussed and remarks are made on the morphologically similar P. metabifolia Maek. in E Asia. All known Nordic intermediates are listed.     

Identification of two nuclear polyhedrosis viruses from the cabbage moth, Mamestra brassicae (Lepidoptera: Noctuidae)

Two nuclear polyhedrosis viruses from the cabbage moth Mamestra brassicae found in two geographical areas in Europe have been characterized and compared. These two virus isolates have similar biological activities and have the same host range. The two M. brassicae nuclear polyhedrosis viruses can be distinguished by restriction endonuclease analysis of their DNA. They appear to be distinct but related virus strains.     

Chemoreceptors in the cibario-pharyngeal pump of the cabbage looper moth,Trichoplusia ni (Lepidoptera: Noctuidae)

The structure of contact chemoreceptors in the cibariopharyngeal pump of the moth Trichoplusia ni (Lepidoptera: Noctuidae) is described. Two types of receptors designated A and B are located on the floor of the pump. Two groups of 9-12 A receptors are located in the anterior part of the pump, and two groups of two B receptors are in the posterior part of the pump. Five sensory dendrites extend to the tip of each A receptor and four to each B receptors. Available evidence indicates that these receptors are contact chemoreceptors and do not serve as mechanoreceptors. The receptors are compared to those of other insects.     

Susceptibility of potato tuber moth (Lepidoptera: Gelechiidae) to postharvest gamma irradiation

Gamma irradiation doses applied to inhibit potato sprouting were tested against potato tuber moth larval and pupal stages. Young larvae and pupae were more susceptible to irradiation injuries than older ones. When larvae of different ages were exposed to doses > or = 100 Gy, only 13-35% pupated, but no adult emergence was obtained. The exposure of 1-1.5- or 3-3.5-d-old pupae to 150 Gy induced high level of sterility and remarkable reduction in female mating ability and fecundity, whereas the reduction was less noticeable for 5-5.5-d-old pupae. Postharvest gamma irradiation of potatoes could be considered as an efficient control approach against potato tuber moth larval and pupal infestations.     

Processes of isolation and introgressive interplay between Platanthera bifolia (L.) Rich and P. chlorantha (Custer) Reichb. (Orchidaceae)

NILSSON, L. A., 1983. Processes of isolation and introgressive interplay between Platanthera bifolia L. Rich, and P. chlorantha (Custer; Reichb. (Orchidaceae). Platanthera bifolia and P. chlorantha are highly specialized for pollination by crepuscular and nocturnal Lepidoptera. The plants are largely sympatric, have overlapping flowering-times, and are completely interfertile. Principal differences exist in floral fragrance and column morphology. Isolation is effected by a set of integrated morphological, ethological, and seasonal mechanisms. Odour-based constancy by moths, differences in column structure, attachment of pollinaria, spurlength, nectar availability, and flowering-peaks reduce interspecific pollen transfer. The plants form a functional species pair in relation to their pollination environment and locally share the same main pollinator species.
Hybrids, which infrequently occur in areas of sympatry, emit a blend of the species-specific fragrance compounds and have intermediate column structure. They are frequently visited by-moths but suffer a serious reduction in seed production due to imperfect interaction vis-à-vis the pollen vectors. Hybrid viscidia, in an intermediate position on the column, are touched by moths' scaly and hairy palps and get insufficient attachment, evidently causing hybrids to act solely as female recipient. First backcross individuals largely join the functional range of either species which promotes rapid introgression. The two gene-pools interplay, although always at a low level. Patterns of introgressive hybridization were exemplified.     

Aestival dormancy in the cabbage moth Mamestra brassicae L. (Lepidoptera: Noctuidae)

Summary A highly specific recognition system, capable of foreseeing and distinguishing between two critical points in time, exists in Mamestra brassicae (Lepidoptera: Noctuidae). Both points in time, the onset of a drought period and the end of the growth season, require different growth patterns of the pupae. In order to minimize the likelihood of weather-induced mortality and to maximize fitness, individuals of M. brassicae must enter aestival dormancy or hibernal diapause, respectively, before the onset of drought or frost. This study is primarily concerned with aestival dormancy. Normally, the pupal period of dormancy-free developing individuals amounts to approximately 20 to 30 days. A modified pupal period of approximately 35 to 80 days is defined as aestival dormancy. The onset of aestival dormancy is triggered by day lengths exceeding an innate individaul-specific threshold. The results reported in this paper indicate that the photoperiodic response curve represents largely the genetic variability within a population with respect to the thresholds triggering aestival dormancy. This variability in thresholds is considered to reflect the frequency of correlation of a distinct day length with a certain onset of drought period in the past. Furthermore, the innate thresholds are characterized by a temperature dependent norm of reaction. Our results also indicate, that a strong genetical component is involved in variability of duration of the pupal period. This variability in duration of aestivation reflects the frequency of drought periods of a certain length in the past. The adaptive significance of both the variation in day length thresholds and duration of aestival dormancy is discussed with respect to the number of generations per season, and the synchronization of the individual life cycles with the seasonal changing environmental conditions.This study is dedicated to Prof. H.J. Müller, Jena, for his 75th anniversaryThis research was supported by the Deutsche Forschungsgemeinschaft (Sa 259/3-1)     

Comparative susceptibilities of diamondback moth (Lepidoptera: Plutellidae) and cabbage looper (Lepidoptera: Noctuidae) from Minnesota and south Texas to lambda-cyhalothrin and indoxacarb

The susceptibility of early instars of diamondback moth, Plutella xylostella (L.), and early (first and second) and late instars (third and fourth) of cabbage looper, Trichoplusia ni (Hübner), from Minnesota and south Texas, to indoxacarb and lambda-cyhalothrin was determined in the laboratory. Susceptibilities of the two species from the two geographical locations to indoxacarb and lambda-cyhalothrin varied greatly. P. xylostella from Minnesota was as susceptible to indoxacarb as those from south Texas, whereas both early and late instar T. ni from south Texas were significantly more tolerant to indoxacarb than those from Minnesota. The LC50 values of indoxacarb for early and later instar T. ni at 48 h from south Texas were 4.3- and 34.0-fold greater than those from Minnesota, respectively. Similarly, early instar P. xylostella and late instar T. ni from south Texas were significantly less susceptible to lambda-cyhalothrin than those from Minnesota. Percentage mortality of the two insect species caused by the two insecticides varied with time of exposure and generally exhibited similar patterns of responses to different concentrations for each insecticide.     

Genetic differentiation in Scottish populations of the pine beauty moth, Panolis flammea (Lepidoptera: Noctuidae)

Pine beauty moth, Panolis flammea (Denis & Schiffermüller), is a recent but persistent pest of lodgepole pine plantations in Scotland, but exists naturally at low levels within remnants and plantations of Scots pine. To test whether separate host races occur in lodgepole and Scots pine stands and to examine colonization dynamics, allozyme, randomly amplified polymorphic DNA (RAPD) and mitochondrial variation were screened within a range of Scottish samples. RAPD analysis indicated limited long distance dispersal (FST=0.099), and significant isolation by distance (P<0.05); but that colonization between more proximate populations was often variable, from extensive to limited exchange. When compared with material from Germany, Scottish samples were found to be more diverse and significantly differentiated for all markers. For mtDNA, two highly divergent groups of haplotypes were evident, one group contained both German and Scottish samples and the other was predominantly Scottish. No genetic differentiation was evident between P. flammea populations sampled from different hosts, and no diversity bottleneck was observed in the lodgepole group. Indeed, lodgepole stands appear to have been colonized on multiple occasions from Scots pine sources and neighbouring populations on different hosts are close to panmixia.     

Aestival dormancy in the cabbage moth Mamestra brassicae L. (Lepidoptera: Noctuidae)

Summary In a geographically wide distribution the life cycles of different populations of the cabbage moth Mamestra brossicae are adapted to a remarkable diversity of climatic conditions. This is undoubtedly a proof of its success in adaptation. Some populations living in regions characterized by a drought period interrupting the growth season are capable of distinguishing between one critical day length signalling the onset of the drought period and another signalling the end of the growth season. This study, therefore, is primarily concerned with the geographical patterns in the variability of the adaptional responses of populations exposed to environmental conditions requiring different strategies and tactics in, synchronizing individual, life cycles. It is also a contribution to our understanding of evolutionary mechanisms maintaining median responses to photoperiodically inductive day lengths in geographically different populations. The populations investigated originated from regions differing in predictability of the incidence, onset and duration of a drought period: Freiburg (48.0°N, Southern Germany), Avignon (44.0°N, Southern France), and Argelès (42.5°N, Southern France). Geographical variation with respect to both onset and duration of a drought period consequently results in clinal variation of the variability of innate day length thresholds triggering aestival dormancy and of innate duration of aestivation. In this paper we considered the influence of geographically changing temperatures on aestival dormancy induction. Even in southern populations of M. brassicae a temperature dependent switch off-mechanism exists which prevents aestival dormancy under certain environmental conditions. The effective temperatures vary geographically, too. What the geographical patterns in adaptive responses really are, is discussed.This research was supported by the Deutsche Forschungsgemeinschaft (Sa 259/3-1)     

嘴壶夜蛾的形态、生活史及昼夜节律

嘴壶夜蛾Oraesia emarginata (Fabricius)是危害水果果实的重要害虫之一, 其成虫和幼虫取食不同的寄主植物, 可以作为理想的嗅觉研究模式昆虫。为了全面地了解嘴壶夜蛾的形态特性和生物学特性, 本实验通过室内饲喂和红外摄像机观察, 对嘴壶夜蛾各虫态的外部形态、 发育以及昼夜活动节律进行了系统研究。结果表明： 嘴壶夜蛾的各龄幼虫可以通过体色, 体表色斑的类型、 位置和数量, 以及腹足的数量进行区别。通过蛹的生殖孔和成虫触角能够很好地区别雌雄。在室内饲养条件下, 嘴壶夜蛾的寿命为53.18±1.70 d, 存活率为63.62%±2.15%, 其中幼虫的发育历期最长, 存活率最低, 卵的发育历期最短, 存活率最高, 雄成虫的存活时间显著长于雌成虫（P=0.008）。6龄幼虫的发育历期（5.29±0.15 d）显著长于其余各龄幼虫（P<0.001）。同一龄发育中期幼虫的体长和体重显著大于将蜕皮幼虫和刚蜕皮幼虫（P≤0.037）; 第2-6龄刚蜕皮幼虫的体重和体长与前一龄发育中期幼虫之间没有显著差异（P≥0.106）。幼虫在光期的孵化、 蜕皮和化蛹比例高于暗期, 而成虫在暗期的飞行、 产卵比例高于光期, 成虫的飞行随着暗期时间的增加而逐渐变少, 光期成虫的飞行主要在开灯之后1 h。成虫交配集中在暗期的第3-5 小时。本研究结果有助于制定有效的嘴壶夜蛾防治措施, 而且为嘴壶夜蛾作为嗅觉研究模式奠定基础。     

小地老虎雄蛾对雌蛾性信息的EAG反应

利用触角电位记录（EAG）技术,测定了小地老虎Agrotis ypsilon (Rottemberg) 雄蛾对性信息素标准化合物Z7-12：Ac（A）、Z9-14：Ac（B）、Z11-16：Ac（C）、Z5-10：Ac（D）和Z8-12：Ac（E）的EAG反应。结果表明：这些标准化合物均能引起EAG反应,其中组分A（Z7-12：Ac）引起的反应最强,为5.65 mV,组分B（Z9-14：Ac）和C（Z11-16：Ac）居中; 组分D（Z5-10：Ac）的EAG反应值最小,为2.50 mV。二元混合物、三元混合物、四元混合物和全组分的EAG反应较高,其EAG反应值均显著高于单组分的反应值。三元混合物ABC的反应值最高,与5头雌蛾腺体的正己烷浸提液的EAG值相当。在使用剂量为0.01 ng～100 μg反应内,小地老虎雄蛾触角对性信息素各组分及其混合物的剂量反应曲线大致呈“S”形。从不同日龄雄蛾对标准化合物的反应中,发现在羽化后第3天达到最高值,之后则随日龄增加EAG反应降低。