Biology of Leipothrix dipsacivagus (Acari: Eriophyidae), a candidate for biological control of invasive teasels (Dipsacus spp.)

The present study describes key aspects of the biology of Leipothrix dipsacivagus, an eriophyid mite that is under study as a biological control candidate of Dipsacus fullonum and D. laciniatus (Dipsacaceae). Preliminary host-specificity tests have shown that it can develop and reproduce only on Dipsacus spp. (teasels). Studies were conducted in a laboratory at 26 ± 2^oC with 16 h of light per day. Mites for the stock colony were collected from D. laciniatus in Klokotnitsa, Bulgaria and reared on rosettes of D. laciniatus in the laboratory. Unfertilized L. dipsacivagus females reared in isolation from the juvenile stage produced male offspring only, while progeny of fertilized females were of both sexes, suggesting arrhenotokous parthenogenesis with haplodiploid sex determination. Experiments were designed to compare male progeny from fertilized females to males from unfertilized females and to compare males and females from fertilized females. Male progeny of virgin mothers had significantly longer durations of active immature stages and total egg-to-adult period than male progeny of fertilized females. Female progeny had significantly longer durations of egg incubation, active immature stages and egg-to-adult period than male progeny from fertilized mothers. Adult longevity was significantly greater in females than in males. Fertilized females produced significantly more eggs per day and overall than virgin females. The results of this study suggest that fertilization status of L. dipsacivagus females can affect both their own fecundity and the development of their male progeny.     

Micro-morphological alterations in young rosette leaves of Dipsacus laciniatus L. (Dipsacaceae) caused by infestation of the eriophyid mite Leipothrix dipsacivagus Petanovic et Rector (Acari: Eriophyoidea) under laboratory conditions

The present study describes micro-morphological and histological changes to rosette leaves of the native Eurasian plant species Dipsacus laciniatus (Dipsacaceae) provoked by infestation of the eriophyid mite Leipothrix dipsacivagus Petanovic et Rector. Conspicuous injuries to the leaf tissue were induced by mites feeding on leaves of D. laciniatus rosettes that were propagated from seed under laboratory conditions. Anatomical injuries extended into epidermal cells on the upper and lower leaf surface as well as to the mesophyll layer of infested D. laciniatus leaves. Statistical analysis (by ANOVA and MANOVA) showed significant differences between control and infested plants, particularly in total leaf thickness. The most striking change observed was the decrease in thickness of infested leaves, beginning from the 8th week, associated with the progressive replacement of epidermal cells with an acellular layer. Measures of mite density on test leaves indicated that mites vacated leaves as russeting symptoms intensified. They also appeared to vacate all leaves, whether symptomatic or not, after populations peaked 10–12 weeks after infestation. Comparisons were made between these studies and those on naturally infested, field-collected D. laciniatus plants, as well as with similar studies of other mite-plant interactions.     

Beitrag zur Keimungsökologie und Diasporologie vonDipsacus sylvestris,Dipsacus laciniatus,Cephalaria transsylvanica,Virga strigosa undVirga pilosa

Im Verlauf einiger Jahre wurde die Keimungsökologie der Früchte vonDipsacus sylvestris Huds.,Dipsacus laciniatus L.,Cephalaria transsylvanica (L.)Schrad. exRoem. etSchult.,Virga strigosa (Willd. exRoem. etSchult.)Holub undVirga pilosa (L.)Hill im Laboratorium und auf einer Versuchsparzelle in Pr?honice studiert. Durch Versuche mit mehreren Fruchtproben wurde festgestellt, dass die Früchte der ArtenDipsacus sylvestris, Dipsacus laciniatus undCephalaria transsylvanica ohne Samenruhe keimen können, während die Früchte vonVirga strigosa undVirga pilosa eine tiefere Samenruhe durchmachen, die durch den physiologischen Zustand des Keimes verursacht ist. Die Dormanz wurde nur in der Erde oder bei kalter Stratifikation unterbrochen. Weiter wurden bei einzelnen Arten verschiedene Beobachtungen und Versuche über Phänologie der Keimpflanzen, die Schwimmfähigkeit der Früchte und Disseminationzeit der Früchte durchgeführt.     

Genome size in Dipsacaceae and Morina longifolia (Morinaceae)

Dipsacaceae and Morinaceae have for a long time been regarded as separate but related families, whereas according to APG III they are included within the larger family Caprifoliaceae. Although genome size studies seldom provide conclusive characters for higher level systematics, they can yield useful information at a lower taxonomy level. In this study, we used DNA flow cytometry (supplemented by Feulgen densitometry) for measurement of genome size variation in the Dipsacaceae genera Cephalaria, Dipsacus, Knautia, Lomelosia, Pterocephalus, Scabiosa, Sixalix, Succisa, and Succisella, and Morina of the Morinaceae. At the monoploid level the Dipsacaceae genera (x = 7–10) vary 5.94-fold between 0.902 and 5.362 pg DNA (1Cx-value), whereas Morina longifolia (x = 17) has only 0.670 pg DNA. At the holoploid level 11.58-fold variation occurs between 0.902 and 10.446 pg DNA (1C-value). In Knautia sect. Trichera ploidy levels 2x, 4x, 6x are accompanied by corresponding increments of C-values, but genome downsizing is observed. In Knautia sect. Tricheroides the only investigated species K. integrifolia (2n = 20) has only 0.60-fold the mean genome size of sect. Trichera. Scabiosa canescens (2n = 2x = 16) has approximately double the C-value of all other Austrian Scabiosa species at the diploid level (pseudopolyploidy). These values raise concern against DNA-ploidy estimations at the interspecific level when chromosome numbers are unknown. The species sorted into two major clades of an existing phylogenetic tree of Dipsacaceae differ characteristically in their range of Cx-values. The Knautia–Cephalaria–Dipsacus–Succisella clade has the great majority of its Cx-values larger than those of the Scabiosa–Pterocephalus–Lomelosia clade.     

Quinacrine fluorescence analysis of the chromosomes of Dipsacus fullonum L. (Dipsacaceae)

Abstract

Quinacrine fluorescence analysis of the chromosome complement of Dipsacus fullonum L. shows clear heterochromatic regions appearing as brightly fluorescent bands or clusters of fluorescent dots in most chromosomes. The resulting fluorescent pattern is chromosome specific.     

Activity of potential predators of European hare (<Emphasis Type="Italic">Lepus europaeus</Emphasis>) leverets and ground-nesting birds in wildflower strips

The population decline of the European hare (Lepus europaeus) in Switzerland is generally attributed to low leveret survival. A significant intensification of agricultural practices led to a landscape transformation that reduced leveret survival by increasing negative factors such as predation pressure. Habitat improvement by means of wildflower strips has yielded some positive effects on European hare population trends, probably by improving food supply and providing year-round cover from predation. For this study, remote cameras were used to examine relationships between landscape and wildflower strip variables and the frequency of predator visits to wildflower strips as well as the probability of them visiting core areas of the strips. Of a total of 1586 visits of potential predators to wildflower strips, 91% were mammals and 9% were birds. Predators were more frequently observed at the edges of the wildflower strips than in their cores (72% of visits by mammalian predators and 76% by avian predators were at the edge). The results revealed that the frequency of observing predators was negatively correlated with adjacent crop height and the distance of the wildflower strip from settlements, roads and forests or hedgerows. The probability of a predator penetrating the core of the wildflower strip was negatively correlated with the vegetation cover, especially with the cover of wood, herbaceous plant species and teasel (Dipsacus fullonum). Appropriate management of wildflower strips by considering their spatial placement, creating low margin to surface area ratios and promoting heterogeneous wildflower structure can thus lead to reduced predator pressure on leverets as well as on ground-nesting birds.     

Carnivory in the teasel Dipsacus fullonum--the effect of experimental feeding on growth and seed set

The teasel, Dipsacus fullonum is known to catch invertebrates in its water filled leaf bases, but experimental testing of reproductive benefits of this have been lacking. We report the effects of insect supplementation/removal and water removal during spring/summer on Dipsacus in two field populations. There were no significant treatment effects on biomass, but addition of dead dipteran larvae to leaf bases caused a 30% increase in seed set and the seed mass:biomass ratio. This study provides the first empirical evidence for reproductive benefit from carnivory in Dipsacus fullonum.     

Non-crop vegetation associated with chili pepper agroecosystems promote the abundance and survival of aphid predators

Habitat manipulation has long been used as strategy to enhance beneficial insects in agroecosystems. Non-crop weed strips have the potential of supplying food resources to natural enemies, even when pest densities are low. However, in tropical agroecosystems there is a paucity of information pertaining to the resources provided by non-crop weeds and their interactions with natural enemies. In this study we evaluated (a) whether weeds within chili pepper fields affect the diversity and abundance of aphidophagous species; (b) whether there are direct interactions between weeds and aphidophagous arthropods; and (c) the importance of weed floral resources for survival of a native and exotic coccinellid in chili pepper agroecosystems. In the field, aphidophagous arthropods were dominated by Coccinellidae, Syrphidae, Anthocoridae, Neuroptera and Araneae, and these natural enemies were readily observed preying on aphids, feeding on flowers or extrafloral nectaries, and using plant structures for oviposition and/or protection. Survival of native Cycloneda sanguinea (Coleoptera: Coccinellidae) differed between plant species, with significantly greater survival on Ageratum conyzoides and Bidens pilosa. However, no evidence was gathered to suggest that weed floral resources provided any nutritional benefit to the exotic Harmonia axyridis (Coleoptera: Coccinellidae). This research has provided evidence that naturally growing weeds in chili pepper agroecosystems can affect aphid natural enemy abundance and survival, highlighting the need for further research to fully characterize the structure and function of plant resources in these and other tropical agroecosystems.     

Survey for natural enemies of the invasive alien chrysomelid, Diabrotica virgifera virgifera, in Central Europe

The western corn rootworm, Diabrotica virgifera virgifera LeConte(Coleoptera: Chrysomelidae), is the mostdestructive pest of maize (Zea mays L.)in North America, and began to successfullyinvade Central Europe in the early 1990's. Thispaper reports a three-year field surveyconducted in Hungary, Yugoslavia, and Croatia,which are currently the focal points ofinvasion, with the aim to determine theoccurrence of indigenous natural enemies ofD. v. virgifera in Europe. A total of9,900 eggs, 550 larvae, 70 pupae and 33,000adults were examined for the occurrence ofparasitoids, nematodes, and fungal pathogens. It can be concluded from the survey resultsthat effective indigenous natural enemies arenot attacking any of the life stages of D.v. virgifera in Europe. The exception is theoccurrence of the fungi Beauveriabassiana (Bals.) Vuill. (Mitosporic fungi;formerly Deuteromyces) and Metarhiziumanisopliae (Metsch.) Sorok (Mitosporic fungi)attacking adults of D. v. virgifera at anextremely low level (< 1%). However no otherentomopathogenic fungal pathogens,entomopathogenic nematodes, or parasitoids werefound on eggs, larvae, pupae or adults. Whileseveral natural enemies in North and CentralAmerica are known to attack D. v.virgifera, it is apparent that indigenousnatural enemies in Europe have not adapted tothe high population density of the alieninvasive species D. v. virgifera. Classical biological control may provide anopportunity to reconstruct the natural enemycomplex of an invading alien pest, and itsapplication to manage D. v. virgiferapopulations in Europe should be considered.     

From Asian curiosity to eruptive American pest: Megacopta cribraria (Hemiptera: Plataspidae) and prospects for its biological control

The kudzu bug or bean plataspid, Megacopta cribraria (Fabricius), is native to Asia where it appears to be widely distributed (although the taxonomy is not entirely clear), but is infrequently a pest of legumes. This bug appeared in 2009 in the southeastern United States, where it is closely associated with kudzu, Pueraria montana Lour. [Merr.] variety lobata [Willd.] Maesen & S. Almeida. However, the insect has become a consistent economic pest of soybeans, Glycine max (L.) Merr., and some other leguminous crops in areas where large numbers can build in kudzu, in addition to being a considerable nuisance in urban landscapes where kudzu occurs. The insect has remarkable capacity for movement and has spread rapidly from nine Georgia counties in 2009 to seven states in 2012. Despite being a nuisance in urban areas and a crop pest, high populations of the bug also reduce the biomass of kudzu, which is itself a seriously problematic invasive weed, complicating the status of M. cribraria in its expanded range. Extant predators and a pathogen in the US have been observed attacking kudzu bugs in the laboratory and field, but no parasitism of eggs or nymphs has been observed to date. A single record of parasitism of an adult kudzu bug by a tachinid fly is known from the US, but no other adult parasitism has been observed in the US or elsewhere. Extant enemies may eventually significantly reduce the bug’s populations, but at present native enemies appear to be insufficient for the task, and exotic enemies from the kudzu bug’s native range may offer the best possibility for effective biological control in the US. Based on the available literature, the best option for an importation biological control program appears to be the platygastrid egg parasitoid Paratelenomus saccharalis (Dodd) because of its apparent host specificity, intimate biological linkages with M. cribraria, and wide geographic distribution in the Eastern Hemisphere. Other natural enemies may eventually emerge as good candidates for importation, but at present P. saccharalis appears to be the most promising.     

Speciation on a local geographic scale: the evolution of a rare rock outcrop specialist in Mimulus

Speciation can occur on both large and small geographical scales. In plants, local speciation, where small populations split off from a large-ranged progenitor species, is thought to be the dominant mode, yet there are still few examples to verify speciation has occurred in this manner. A recently described morphological species in the yellow monkey flowers, Mimulus filicifolius, is an excellent candidate for local speciation because of its highly restricted geographical range. Mimulus filicifolius was formerly identified as a population of M. laciniatus due to similar lobed leaf morphology and rocky outcrop habitat. To investigate whether M. filicifolius is genetically divergent and reproductively isolated from M. laciniatus, we examined patterns of genetic diversity in ten nuclear and eight microsatellite loci, and hybrid fertility in M. filicifolius and its purported close relatives: M. laciniatus, M. guttatus and M. nasutus. We found that M. filicifolius is genetically divergent from the other species and strongly reproductively isolated from M. laciniatus. We conclude that M. filicifolius is an independent rock outcrop specialist despite being morphologically and ecologically similar to M. laciniatus, and that its small geographical range nested within other wide-ranging members of the M. guttatus species complex is consistent with local speciation.     

西藏被子植物新记录

报道了西藏被子植物3种新记录,即石竹科(Caryophyllaceae)的坚硬女娄菜(Silene firma Sieb.et Zucc.)、川续断科(Dipsacaceae)的绿花刺参(Morina chlorantha Diels)和菊科(Asteraceae)的粘毛香青[Anaphalis bulley-ana(J.F.Jeffr.)Chang].     

Duplication of the structural gene for glucosephosphate isomerase and phosphogluconate dehydrogenase inScabiosa columbaria and their phylogenetic implications in the dipsacaceae

Zymograms of glucosephosphate isomerase (GPI) and phosphogluconate dehydrogenase (PGD) revealed three isozymes for each enzyme in the plant speciesScabiosa columbaria. Intergenic heterodimers are formed between the polypeptides coded byGpi-1 andGpi-2 and between those coded byPgd-1 andPgd-2, indicating that a GPI and a PGD locus have been duplicated in the past. The ancestral genes assort independently with their duplicated gene, suggesting that the duplications have originated from a process of translocation. Linkage was found only betweenGpi-1 andPgd-2 and betweenGpi-2 andPgd-1, suggesting that the duplicated loci were located on the same translocated chromosomal segment. Both duplications are present in all other examined species ofScabiosa and inCephalaria andKnautia, two other genera of the Dipsacaceae. The generaSuccisa andDipsacus, also belonging to the Dipsacaceae, do not showGpi-1 activity, makingGpi-2 andPgd-1 the most likely ancestral genes. InSuccisa, the isozymes ofGpi-1 andGpi-2 either overlap orGpi-1 has been silenced. The combined results suggest that a chromosomal segment containingGpi-2 andPgd-1 has been translocated before the divergence ofScabiosa, Cephalaria, Knautia, andSuccisa.     

Phylogenetic overview of Erysiphaceae based on nrDNA and MCM7 sequences

The classification system and evolutionary history of Erysiphaceae have been studied based on the results of molecular phylogenetic analyses. However, the sequence data used for these phylogenetic estimations have been limited to the nrDNA of ca., 50 taxa, and the relationships among higher taxonomic groups are not well understood. To provide a phylogenetic overview of Erysiphaceae, we performed phylogenetic estimations based on nrDNA and MCM7 sequences obtained from ca., 270 taxa. The phylogenetic tree showed a similar topology to the trees obtained in previous studies, although the branching order between Golovinomyceteae and Phyllactinieae was different and Phyllactinieae was not monophyletic. Phyllactinieae and Erysipheae were estimated to diversify after the divergence of Golovinomyceteae, suggesting an evolutionary trend in which non-catenate conidia + endoparasitic or non-catenate conidia + ectoparasitic lineages were derived from catenate conidia + ectoparasitic lineages. Phyllactinieae was divided into a clade of Phyllactinia + Leveillula and other clade(s) consisting of Pleochaeta and Queirozia. The phylogenetic hypothesis of Erysiphaceae was updated based on the largest dataset to date, but the higher-level phylogenetic relationships remain unclear. For a more robust phylogenetic hypothesis of Erysiphaceae, further sequence data, including protein coding regions, should be added to the dataset of nrDNA sequences.     

贵州省烟田杂草优势种群的种间联结关系

在样方调查的基础上,采用方差比率法、Pearson点相关系数和X²检验分析贵州烟田杂草优势种群的种间关系。结果表明：①贵州省烟田杂草优势种的总体联结性为显著的正联结,处于比较稳定的状态;②Pearson点相关系数有21个种对呈正相关,23个种对呈负相关,尼泊尔蓼与繁缕无联结关系;③牛膝菊与马唐、尼泊尔蓼之间正联结关系达到极显著水平,牛膝菊与鸭趾草、马唐与尼泊尔蓼之间正联结关系为显著水平,其他种对之间均为不显著水平。本文旨在了解和掌握烟田杂草在群落中的分布状况,烟田杂草群落的演替趋势及为烟田杂草的防除提供基础资料。     

Inadvertent biological control: an Australian thrips killing an invasive New Zealand tree in California

Transport hubs of international trade and tourism are sites of unprecedented long-distance dispersal of species and novel ecological interactions. In cases of invasive plants released from their specialist natural enemies, novel interactions with both resident enemies and new arrivals can accumulate and potentially reduce weed competitiveness. I present here one dramatic example of this, where an invasive woody weed in southern California is being rapidly controlled by an accidentally introduced genus-specialist herbivorous insect. The New Zealand native shrub/small tree, Myoporum laetum, is a long-time popular ornamental plant in California and has become an invasive woody weed. In 2005, a Myoporum-specific thrips, Klambothrips myopori, was discovered (and described) in California feeding on M. laetum leaves. Several searches have failed to find K. myopori in New Zealand and a population has recently been discovered in Tasmania, Australia, feeding on Myoporum insulare. In 5 years, K. myopori has killed off about half of southern Californian M. laetum with almost all surviving individuals being gradually defoliated. Inadequate border biosecurity has resulted in inadvertent biological control, in a rapid timeframe, caused by a novel enemy. Unfortunately, K. myopori has subsequently been accidentally transported from California to Hawaii where it is now killing off Hawaiian native Myoporum sandwicense. Transport hubs can both connect weeds with natural enemies and disperse those enemies more widely.     

Four New Ladybug Species Belonging to Decadiomus Chapin (Coleoptera: Coccinellidae) from Puerto Rico

While searching for native natural enemies attacking invasive insect pests in Puerto Rico, we found four undescribed ladybug species belonging to the Caribbean ladybug genus Decadiomus Chapin. In this article, we describe the following species from Puerto Rico: Decadiomus seini n. sp., Decadiomus ramosi n. sp., Decadiomus hayuyai n. sp., and Decadiomus martorelli n. sp. Illustrations of the dorsal habitus, shape of prosternal carinae, and drawings of male and female genitalia are presented. We also present a key for Diomini of Puerto Rico and discuss their importance as potential biocontrol agents.     

3种海拔高度茶园中2种害虫与其天敌间的数量和空间关系

用灰色系统分析法和生态位分析法对安徽省潜山县高、中、低3种海拔茶园中2种主要害虫与其天敌在数量和空间上的相互关系进行研讨,经综合排序得出:低海拔茶园假眼小绿叶蝉的主要天敌是锥腹肖蛸、茶色新圆蛛和鞍型花蟹蛛,中海拔茶园为八点球腹蛛、锥腹肖蛸和鞍型花蟹蛛,高海拔茶园为锥腹肖蛸、茶色新圆蛛和草间小黒蛛。低海拔茶园柑橘粉虱的主要天敌是八点球腹蛛、茶色新圆蛛和异色瓢虫,中海拔茶园为鞍型花蟹蛛、八点球腹蛛和茶色新圆蛛,高海拔茶园为锥腹肖蛸、八点球腹蛛和斑管巢蛛。上述几种天敌与2种主要害虫在数量和空间上有显著的追随关系。不同海拔高度茶园中2种主要害虫的主要天敌种类存在差异。     

Responses of the specialist biological control agent,Aleochara bilineata,to vegetational diversity in canola agroecosystems

Plant biodiversity is known to affect insect populations, both herbivores and their natural enemies, and as a consequence, habitat management through increased plant species composition and abundance can be exploited for sustainable pest management. In agroecosystems where crop monocultures are the routine production practice, plant biodiversity can be increased by maintaining small populations of weeds, with potential beneficial effects arising from concomitant increases in the abundance of predator and parasitoid populations. We manipulated weed populations in both species of canola, Brassica rapa L. and Brassica napus L., to investigate responses of adults of Aleochara bilineata Gyllenhal (Coleoptera: Staphylinidae), an important natural enemy of root maggots (Delia spp., Diptera: Anthomyiidae). Larval root maggots feed on canola taproots, disrupting the flow of water and nutrients within the plants, causing substantial yield reductions. Aleochara bilineata is a predator–parasitoid that attacks all root maggot pre-imaginal life stages. Activity density of A. bilineata increased as monocotyledonous weed biomass declined. Significant preferences between canola species were observed, with A. bilineata associated most frequently with B. rapa compared with B. napus. Our research suggests that improved management of root maggot infestations in canola through enhancement of populations of the A. bilineata predator–parasitoid could be accomplished by reducing weed infestations; however, such recommendations should consider other predators in the system and the role of weeds in reducing root maggot oviposition and damage.