Helianthus annuus pollen, an oviposition stimulant for the sunflower moth, Homoeosoma electellum

Females of the sunflower moth, Homoeosoma electellum, laid a total of 242.3±27.4 (X±SE) eggs when provided oviposition sites of wax paper dusted with pollen from cultivated sunflowers. Fecundity was influenced by the age at which mating occurred but not by the duration of mating. Eggs were laid during both the light and dark portions of a 16L:8D photoperiodic cycle, with an evident peak occurring shortly after the onset of the scotophase.The fecundity of females provided oviposition sites with a 1 mg equivalent of an ethanolic pollen extract daily (124.2±22.8) did not differ significantly from that of females provided 1 mg of pollen (172.2±28.0). Furthermore, the females showed the same positive dose dependent oviposition response where sites contained different concentrations of either pollen or pollen extract. However, when different oviposition substrates were provided simultaneously, females preferred pollen > reconstituted pollen (extract + pollen residue following extraction) = pollen extract > pollen residue = wax paper control. These data confirm the presence of an oviposition stimulant for H. electellum in the sunflower pollen.Antennectomised females laid as many eggs on sites with pollen residue as on sites with pollen, indicating that the majority of sensillae for detecting the oviposition stimulant are located on the antennae.The importance of pollen load as an indicator of a suitable host plant, given that previous laid eggs do not inhibit subsequent oviposition, is discussed with respect to larval survival.

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Résumé Les femelles de la pyrale du tournesol, Homoeosoma electellum ont pondu un total de 242.3±27.4 (X±SE) oeufs sur des sites de ponte faits de papier ciré et saupoudrés de pollen de tournesol cultivé. La fécondité a été significativement affectée par l'âge des individus au moment de l'accouplement, cependant la durée de l'accouplement n'a pas influencé la fécondité. Sous une cycle de 16L:8D, la ponte a eu lieu aussi bien en phase de lumière que de noirceur mais le pic de la ponte a eu lieu peu après le début de la scotophase.La fécondité des femelles à qui on a offert à chaque jour des sites de ponte traités avec un extrait de pollen à base d'éthanol à une concentration de 1 mg de pollen (124.2±22.8) n'a pas été significativement différente de celle obtenue sur des sites traités avec 1 mg de pollen (172.2±28.0). De plus, le nombre d'oeufs pondu a augmenté en fonction des différentes concentrations de pollen ou de l'extrait de pollen offertes simultanément. Cependant, lorsque différents sites de ponte ont été offerts simultanément, les femelles ont préféré le pollen > le pollen reconstitué (extrait + pollen résiduel après l'extraction) = extrait de pollen > pollen résiduel = papier ciré non traité (témoin). Ces données confirment que le pollen de tournesol contient des substances qui stimulent la ponte de H. electellum.Les femelles antennectomisées ont pondu autant d'oeufs sur des sites traités avec le pollen résiduel que sur ceux traités avec le pollen, ce qui indique que la plupart des sensilles impliquées dans la détection du stimulant de ponte se trouvent au niveau des antennes.Etant donné que la présence des oeufs déjà pondus n'inhibent pas les pontes subséquentes, l'importance de la charge de pollen, comme indice de la bonne qualité de la plante-hôte, est discutée en relation avec la survie des larves.

     

Pericarp strength of sunflower and its value for plant defense against the sunflower moth,Homoeosoma electellum

Sunflower pericarps provide a barrier against seed feeding by larvae of the sunflower moth, Homoeosoma electellum. Pericarp hardening is thought to be accelerated by a phytomelanin layer beneath the hypodermis, but among germplasm with phytomelanin, broad variation in sunflower pericarp strength exists. To facilitate the use of pericarp strength in sunflower breeding, resistance to mechanical puncture was assessed for diverse sunflower germplasm, and feeding tests were used to evaluate whether differences in pericarp strength prevent H. electellum larvae from penetrating achenes. Test on field-grown sunflowers indicates that public restorer lines have lower pericarp strengths compared with maintainer lines and commercial hybrids at 14 days after the start of anthesis. Interspecific crosses or plant introduction (PI) accessions believed to be resistant to H. electellum, including PI 170415, comprised a group with exceptionally high pericarp strength relative to other germplasm. In subsequent tests on greenhouse-grown sunflowers, overall results were similar, but using field-grown plants provided greater statistical power. In choice tests with achenes that differed in pericarp strength, 7- to 9-day-old sunflower moth larvae fed more often on seed protected by a weaker pericarp, at a more than 5-to-1 ratio, while 10-day-old larvae fed indiscriminately. Pericarp strength data contradict previous published results for individual entries and heterotic groups, but support the generalization that improved physical resistance to the sunflower moth is possible. To use pericarp strength in PI 170415 or similar sources, the inheritance of high pericarp strength and potential trade-offs between pericarp strength and other agronomic traits need to be understood.     

Female preference and larval performance of sunflower moth,Homoeosoma electellum,on sunflower pre‐breeding lines

The preference–performance hypothesis for insect herbivores predicts that adult females should preferentially choose hosts on which their offspring perform better. We tested this hypothesis for the sunflower moth, Homoeosoma electellum (Hulst) (Lepidoptera: Pyralidae), using 16 sunflower (pre‐breeding) lines, derived from a number of wild species of Helianthus, including Helianthus annuus L., Helianthus deserticola Heiser, Helianthus paradoxus Heiser, Helianthus praecox Engelm. & Gray ssp. hirtus (Heiser) Heiser, Helianthus praecox Engelm. & Gray ssp. runyonii (Heiser) Heiser, Helianthus petiolaris Nutt., Helianthus resinosus Small, and Helianthus tuberosus L. (Asteraceae), that are suitable for introducing wild sunflower germplasm into commercial cultivars. Female moths showed a range of ovipositional preference measures to the various lines. Combined data for three Helianthus species represented by multiple lines showed significant differences in female preference with respect to the parental species. Larval performance, determined by proportion of infested neonate larvae reaching the pupal stage, or mean pupal weight, varied across the lines and, as for the female preference data, also showed significant differences among the three parental Helianthus species represented by multiple lines. These data suggest that the characteristics in the pre‐breeding lines influencing female sunflower moth preference and larval performance likely originate from the parental species and may be consistently transferred to the derived pre‐breeding lines. Of particular note with regard to potential plant resistance mechanisms, lines derived from H. tuberosus showed consistent low preference–performance measures. Female preference and larval performance (for both measures) were strongly correlated, indicating that females preferred plants and lines on which larvae performed better, in support of the preference–performance hypothesis.     

向日葵螟成虫种群消长动态和空间分布型

为了科学指导应用播期避害、性诱剂诱捕成虫和田间释放天敌昆虫-赤眼蜂防治向日葵螟,确定最佳防治时期和选择最佳防治方法,2009—2011年,在内蒙古巴彦淖尔市利用向日葵螟Homoeosoma nebulellum(Denis et Schiffermüller)性诱剂进行了向日葵螟田间种群动态和空间分布型的研究。结果表明,向日葵螟成虫每年5月中旬始见,直到9月底,一年有两个明显的成虫蛾峰期,第1个蛾峰期出现在6月下旬至7月上旬,第2个蛾峰期在7月下旬至8月中旬,当地向日葵1年受到两代幼虫的危害,而且开花期与向日葵螟两个蛾峰期吻合度越高,向日葵受葵螟幼虫的危害越重;通过应用5种聚集度指数测定和Blackith种群聚集均数λ分析,向日葵螟成虫在田间呈聚集分布,聚集主要由向日葵螟自身行为及环境因素引起。根据成虫动态和空间分布型,可以科学指导应用播期避害、性诱剂诱捕器和释放天敌昆虫的最佳时期及方式。     

Isolation of nine microsatellite loci in Dolichogenidea homoeosomae (Hymenoptera) a parasitoid of the sunflower moth Homoeosoma electellum (Lepidoptera)

Nine microsatellite loci were isolated from the insect Dolichogenidea homoeosomae (Hymenoptera: Braconidae), an important parasitoid of the sunflower moth Homosoeosoma electellum (Lepidoptera: Pyralidae), and assayed for polymorphism. All nine loci were polymorphic within the five populations tested, with two to 14 alleles per locus. Expected and observed heterozygosities ranged from 0.39 to 0.90 and 0.25 to 0.72 respectively. These are the first microsatellite primers developed for D. homeosomae and will be useful for studies of population dynamics and connectivity.     

向日葵螟幼虫的空间分布型及抽样技术

欧洲向日葵螟Homoeosoma nebulellum Denis et Schiffermüller是向日葵上的主要害虫,本文利用6种聚集指标对向日葵螟幼虫的空间分布型进行了测定,结果表明其呈现聚集分布。样本平均数(m)与方差(S2)的对数值的关系式为:lgS2=lg0.2130+0.5639lgm,显示向日葵螟幼虫的空间分布随密度的升高而趋向均匀分布。Iwao的m*-m回归方程为:m*=8.1177+0.1447m,显示该虫在田间分布的基本成分是个体群,个体间相互吸引,个体群的空间分布型为均匀分布。对聚集原因进行分析,得出λ<2,表明向日葵螟幼虫的聚集是由于环境作用所引起的。用Iwao的理论抽样数模型计算出向日葵螟幼虫的理论抽样数模型为:D=0.1时,n=911.77/m-85.53,D=0.2时,n=227.94/m-21.38。采用m*-m关系的序贯抽样模型制定出食葵田间的序贯抽样模型为:T1(n),T0(n)=7.40n±4.54n,油葵田间的序贯抽样模型为:T1(n),T0(n)=10.05n±2.29n。     

A study of the transport and deposition of oilseed rape (Brassica napus L.) pollen in east Fife, Scotland

It has been suggested that there is a link between the relatively recent expansion in the farming of oilseed rape (Brassica napus L.) and an increase in the incidence of respiratory illness in eastern Scotland. However, there is limited evidence of the extent to which one possible cause of this increased illness, the pollen of oilseed rape, is disseminated from fields of this crop. The present study used sedimentation traps and a portable volumetric air sampler to study the transport of pollen from rape fields in Fife, and the results confirmed the widely held view that most of the pollen travels only a short distance from its source. In this case relatively low quantities ofBrassica pollen were detected more than 200 m from fields of rape. This may have implications for the formulation of advice for those who appear to suffer from an allergic reaction to rape crops.     

Neurological influences on pheromone release and calling behaviour in the gypsy moth, Lymantria dispar

ABSTRACT. Surgical removal of the brain or disconnection of the last abdominal ganglion from the ventral nerve cord prevented sex pheromone release in female Lymantria dispar (L.) (Lymantriidae), as assayed by the male wing-fanning response. The calling behaviour continued to occur in individuals whose terminal abdominal ganglion had been thus isolated, however, indicating that the neural mechanisms controlling calling function independently in the last abdominal ganglion.     

A reinvestigation of the role of (E)-2-hexenal in female calling behaviour of the polyphemus moth (Antheraea polyphemus)

Calling periodicities in the saturniid moth Antheraea polyphemus were similar in virgin females that were intact, intact and exposed to (E)-2-hexenal and antennectomised. Virgin females and antennectomised virgin females were of comparable attractiveness to males in the field.     

Conspecific females promote calling behavior in the noctuid moth,Pseudaletia adultera

Changes in female calling behavior in response to the presence of conspecific pheromones (pheromone autodetection) have been demonstrated in a number of moth species. However, the observed changes vary between species, and several ecological and adaptive explanations for autodetection have been proposed. We studied the effect of conspecific females on the calling behavior of the noctuid moth Pseudaletia adultera (Schaus) (Lepidoptera: Noctuidae, Hadenini), by comparing the age of first calling, as well as the onset and pattern of calling, when females were held individually or in the presence of conspecifics. Grouped females started calling at a lower age, a higher percentage of females called during the scotophase, and they called longer compared to females held in isolation. We also demonstrated that female antennae respond to each of the three main components of the sex pheromone – (Z)‐11‐hexadecen‐1‐ol, (Z)‐11‐hexadecen‐1‐yl acetate, and (Z)‐11‐hexadecenal – and that the response patterns differed from those of male antennae. By calling more and extending her calling window in presence of conspecific females, a female may increase her chances of accessing males. However, the potential benefits need to be considered within an ecological context, considering factors such as migration, oviposition, and foraging.     

内蒙古巴彦淖尔地区向日葵螟的种群动态与生活史

为了制定科学、有效的向日葵螟Homoeosoma nebulellum Denis et Schiffermüller（鳞翅目：螟蛾科）测报和防治对策,通过野外调查和室内饲养观察对内蒙古巴彦淖尔地区向日葵螟的发生为害规律及生活史进行了研究。结果表明：当地向日葵螟的寄主有菊科的向日葵Helianthus annuus L.、茼蒿Chrysanthemum coronarium Mill.、刺儿菜Cephalanoplos segetum（Beg.） Kitam和苣荬菜Sonchus brachyotus DC.,其中苣荬菜作为向日葵螟的寄主在我国是首次报道。应用性信息素监测结合田间调查的结果表明,当地向日葵螟一年发生2代,其中越冬幼虫4月下旬开始化蛹,5月中旬开始羽化,但此时羽化的成虫由于缺乏开花寄主而无法产卵为害。第1代幼虫在6月末为害茼蒿、7月下旬开始为害开花的向日葵。第1代幼虫于7月下旬开始羽化产卵形成第2代,其中有9.2%的老熟幼虫直接滞育越冬。第2代幼虫自8月中旬起为害晚开花的向日葵,9月中旬老熟后陆续入土越冬,至10月上旬收获时仍有30.0%的幼虫未老熟而随收获的葵花盘转至筛选出的杂质中越冬。在24℃,RH 70%和L16∶D8光照条件下测定第2代向日葵螟卵、幼虫和蛹的发育历期分别为4.2、15.9和11.1 d,雌、雄蛾寿命分别为14.9 d和15.1 d.综合观察结果,绘制了巴彦淖尔地区向日葵螟的生活史表。     

Sensilla on the larval antennae and mouthparts of the european sunflower moth,Homoeosoma nebulella Den. and Schiff. (Lepidoptera : Pyralidae)

Sensilla on the larval antennae and mouthparts of Homoeosoma nebulella (Lepidoptera : Pyralidae) were examined with a scanning electron microscope. The antenna possesses 2 aporous sensilla chaetica, one aporous sensillum styloconicum, 3 large multiporous sensilla basiconica, and 3 small multiporous s. basiconica. The labrum bears 12 aporous s. chaetica and the epipharynx has 6 aporous flattened s. chaetica and 4 epipharyngeal sensilla. It is the first time that more than 2 epipharyngeal sensilla have been reported in caterpillars. The mandible possesses 4 aporous s. chaetica. Each galea bears 2 uniporous s. styloconica, 2 small aporous s. basiconica, one s. campaniformium and 3 aporous s. chaetica. Each maxillary palp bears a distal group of 8 uniporous s. basiconica, one large s. digitiformium and one pore plate. Minute grooves exist on the s. digitiformium. Each labial palp possesses one aporous s. chaeticum and one aporous s. styloconicum. An attempt has been made to identify the function of sensilla by comparing them with those of other larvae.     

The effect of habitat fragmentation on dispersal patterns, mating behavior, and genetic variation in a pika (Ochotona princeps) metapopulation

 Habitat fragmentation is becoming increasingly common, yet, the effect of habitat spatial structure on population dynamics remains undetermined for most species. Populations of a single species found in fragmented and nonfragmented habitat present a rare opportunity to examine the effect of habitat spatial structure on population dynamics. This study investigates the impact of highly fragmented habitat on dispersal patterns, mating behavior, and genetic variation in a pika (Ochotona princeps) population with a mainland-island spatial structure. Juvenile dispersal patterns in fragmented habitat revealed that individuals tended to disperse to neighboring habitat patches. However, within-patch band-sharing scores from multilocus DNA fingerprints did not differ from what would be expected if individuals were assorting randomly among habitat patches each year. Multiple, short-distance dispersal targets for juveniles and occasional long-distance dispersal events suggest that habitat fragmentation on this scale has not resulted in restricted dispersal and a genetically subdivided population. Although pikas tended to mate with the closest available partner, DNA fingerprinting band-sharing scores between mated pairs were consistent with a random mating hypothesis. Random mating in this population appears to be an incidental effect of dispersal in a fragmented habitat. This pattern is distinct from that found in nonfragmented habitat (large talus patches) where mating was non-random and consistent with mating between individuals of intermediate relatedness. DNA fingerprinting data revealed within-species variation in the mating habits of the pika directly attributable to habitat spatial structure. Received: 4 November 1996 / Accepted: 30 June 1997     

Holocene forest development along the Setesdal valley, southern Norway, reconstructed from macrofossil and pollen evidence

The Setesdal valley in South Norway runs north to south for 200 km, from alpine vegetation at 1200 m, passing the tree-line at around 1000 m, through Boreal forests, to Nemoral forest at sea level. The Holocene vegetation history and its altitudinal differentiation were reconstructed using pollen percentages and influx and plant macrofossil concentration records from four lakes along an altitudinal transect. During the early Holocene (c. 10500–8000 cal b.p.) Betula pubescens, Pinus sylvestris, Alnus, and Corylus expanded in the lowlands. Only Pinus and B. pubescens reached 1000 m asl (Lille Kjelavatn). Only B. pubescens reached Holebudalen (1144 m asl) at about the same time as it arrived in the lowlands. Between c. 8000–3000 cal b.p. mixed deciduous forest developed around Dalane (40 m asl) and to a lesser extent around Grostjørna (180 m asl), birch woodland with pine surrounded Lille Kjelavatn and birch woodland occurred at Holebudalen. From c. 3000 cal b.p. to present, the vegetation at Dalane hardly changed except for slight human impact and the immigration of Picea abies. At Grostjørna Pinus expanded. At Lille Kjelavatn Pinus disappeared and Betula became sparse as at the tree-line today. Betula retreated from Holebudalen thus leaving it above the tree-line in low-alpine vegetation. The strengths and weaknesses of pollen and plant macrofossil data were assessed for forest reconstructions. Where local pollen production is low, as near the tree-line, percentages of long-distance tree pollen can be misleadingly high. Pollen influxes of Betula and Pinus were much smaller near their altitudinal limits than at lower altitudes, although their macrofossils were equally abundant. The limited dispersal capacity of macrofossils documents the local presence of species and the character of the local vegetation, although macrofossils of some tree taxa are rarely found. Pollen and plant macrofossil evidence complement each other to provide a more complete reconstruction of Holocene tree-limits and tree-lines and hence climate changes, than either form of evidence alone.     

Reproductive behavior of the honeydew moth,Cryptoblabes gnidiella

Summary

The reproductive behavior of the honeydew moth, Cryptoblabes gnidiella (Millière) (Lepidoptera: Pyralidae), was studied in the laboratory. The sex ratio was 1.1:1, males to females, in both laboratory and field stocks. Most of the females that mated did so during the first night after emergence; males began mating on the following night. Mating occurred 1–2 h before dawn and averaged 100 min. Both sexes mated only once in one night. Most females mated only once in their lifetime, a few mated 2–4 times, whereas males mated up to six times per lifetime. Insects that lived longer also mated more times. When the sex ratio was altered from 3:1 to 1:3, males to females, the percentage of females that mated in one night dropped from 90 to 65, whereas the number of matings per male rose from 0.32 to 2.25. When fresh one-day-old females were provided daily at a ratio of three per male, the males averaged 1.4 matings per lifetime vs. 2.6 with 2- to 3-day-old females. A delay in mating did not affect the percentages of males and females that mated; highest percentages were obtained with 2- to 4-day-old males and females, but a delay in mating resulted in egg fertility dropping from 91 % to 73 %. The preoviposition period lasted a full day after mating, and then most of the eggs were laid during the first night. Average fecundity was 105 eggs per female (maximum: 230).     

Infection of tomato by Tomato Yellow Leaf Curl Virus alters the foraging behavior and parasitism of the parasitoid Encarsia formosa on Bemisia tabaci

Encarsia formosa Gahan is a solitary endoparasitoid that is commercially reared and released for augmentative biological control of whiteflies including Bemisia tabaci (Gennadius). Bemisia tabaci biotypes B and Q are two most invasive species that greatly reduce crop yields in China by feeding on plant sap and by transmitting Tomato Yellow Leaf Curl Virus (TYLCV). The effects of TYLCV infection of tomato on E. formosa foraging on B. tabaci B and Q are unknown. In Y-tube olfactometer assays in the present study, E. formosa significantly preferred TYLCV-infected tomato plants over TYLCV-free plants. The wasp females also significantly preferred TYLCV-infected tomato plants infested with 3rd-instar nymphs of B. tabaci biotype Q over TYLCV-free plants with biotype Q nymphs. However, no significant differences were observed when B. tabaci biotype B was infested on tomato plants. The oviposition bioassays confirmed that TYLCV infection on tomato plants resulted in the recruitment of parasitoids. These results indicate that TYLCV-infection of tomato increase the foraging of E. formosa on B. tabaci, as differs on the B and Q biotypes.     

灰飞虱的起飞和扩散行为

2005年7月初至9月底,在扬州市邗江区通过田间观察、罩笼试验以及卵巢解剖,初步研究灰飞虱Laodelphax striatellus(Fallén)的起飞行为及其与长翅型密度、天气条件、光照强度、卵巢发育等因素的关系。发现灰飞虱的起飞时段多在日落之后,起飞存在一定的密度阈值和最适光照强度范围,而且在一定程度上表现出"卵子发生—飞行共轭"效应。     

Host plant use by the Heath fritillary butterfly, Melitaea athalia: plant habitat, species and chemistry

We present a study of habitat use, oviposition plant choice, and food plant suitability for the checkerspot butterfly Melitaea athalia Rottemburg (Lepidoptera: Nymphalidae) in Åland, Finland. We found that in Åland, unlike in the mainland of Finland and many parts of its range, M. athalia flies mainly in open meadows. When offered an array of plants in a large (32 × 26 m) field cage, they predominately oviposited upon Veronica chamaedrys L., V. spicata L. and Plantago lanceolata L. (Plantaginaceae), which grow in open meadows. The relative abundance of the butterfly in Åland, and its habitat and host plant use there, may reflect local adaptation to land use practices and geology that maintain clusters of small open meadows with little successional change. At the scale of a plant patch, preferred species were used as frequently in mixed species patches as in mono-specific patches, and more oviposition occurred in open than in grassy patches. All of the host plants used by M. athalia are defended by iridoid glycosides (IGs). However, oviposition choice among species and among individual plants within species was largely independent of IG concentration. This contrast with the more discerning congener, M. cinxia, supports the idea that host discrimination decreases with increasing host range. Finally, although the adult butterflies chose specific plant species for oviposition, as larvae they performed well on twelve out of thirteen species of plants, including both known hosts and related novel plants that occur in Åland, indicating a much wider range of larval food plant species than adult oviposition species.     

Differential localization of the LIM domain protein PLIM-1 in microspores and mature pollen grains from sunflower

 PLIM-1 is a LIM domain protein specifically expressed in pollen grains. Using two PLIM-1-specific monoclonal antibodies we studied its expression and intracellular location at various developmental stages of sunflower (Helianthus annuus L.) pollen. Our studies show that the protein appears at the microspore stage in a limited number of cytoplasmic bodies, becomes undetectable in bicellular pollen, and reappears in tricellular pollen grains in cortical patches particularly concentrated in the F-actin-enriched germination cones of the vegetative cell. The developmental stage-dependent, different location of the protein suggests a dual function during pollen development. While this function in microspore development remains obscure, the high concentration of PLIM-1 in the germination cones of mature pollen suggests that it participates in the germination process as well as in pollen tube growth. Received: 11 August 1998 / Revision accepted: 15 December 1998