Leaf Undersurface Research Articles

Oviposition-site shift in phytophagous mites reflects a trade-off between predator avoidance and rainstorm resistance.

Predators can reduce prey population densities by driving them to undertake costly defences. Here, we report on a remarkable example of induced antipredator defence in spider mites that enhances the risk to rainstorms. Spider mites live on the undersides of host plant leaves and usually oviposit on the leaf undersurface. When they are threatened by predatory mites, they oviposit on three-dimensional webs to avoid egg predation, although the cost of ovipositing on webs has not yet been clearly determined. We prepared bean plants harbouring spider mite (Tetranychus kanzawai) eggs on either leaf surfaces or webs and exposed them to rainstorms outdoors. We found that fewer eggs remained on webs than on leaf surfaces. We then examined the synergistic effect of wind and rain by simulating both in the laboratory. We conclude that ovipositing on webs comes at a cost, as eggs are washed off the host plants by wind and rain. This may explain why spider mite populations decrease drastically in the rainy season, although they inhibit leaf undersides where they are not directly exposed to rainfall.

<p class="Body">Two new species of Eriophyidae (Acari: Trombidiformes: Eriophyoidea) on Tilia begoniifolia Steven (Tiliaceae) in Golestan province of Iran

Two new species belonging to the Eriophyidae were found on Tilia begoniifolia Steven in Golestan province of Iran, and are described and illustrated herein. Eriophyes begoniifoliae sp. nov. was associated to round galls protruded on both surfaces of the leaves. Aculus namdari sp. nov. was vagrant on the leaf undersurface and no damage was observed on the infested plants.

Male sexual competitiveness of two Ceratitis capitata strains, tsl Vienna 8 and OX3864A transgenics, in field cage conditions

AbstractThe success of the sterile insect technique (SIT) depends on the ability of sterile males to compete effectively with wild males to mate with wild females. This study compared the sexual competitiveness and other behavioral parameters of males of two strains of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), tsl Vienna 8 (tsl V‐8) and the transgenic line OX3864A, in competition with wild males from the São Francisco Valley region in Bahia, Brazil. Mating events were observed in field cages containing virgin, sexually mature insects as follows: 50 wild females (10–12 days old), 50 wild males (8–10 days old), and either 50 tsl V‐8 sterile males (5 days old) or 50 transgenic males (3–4 days old). In addition to scoring male type for each mating event, we also monitored the location of mating events within the tree canopy, mating duration, and mating latency. The proportion of females that mated did not differ between the two competition scenarios tested (tsl V‐8 vs. wild males: 0.65 ± 0.04; transgenic vs. wild males: 0.64 ± 0.03). Relative sterility index did not differ between sterile (0.34 ± 0.04) and transgenic males (0.31 ± 0.03). The latency period was significantly longer for transgenic males (84.90 ± 4.87 min) than for sterile (65.24 ± 4.65 min) and wild males (66.61 ± 2.66 min). Mating events involving the three strains occurred in the same area of the tree, i.e., mid‐height, in the central sector and on leaf undersurfaces. The mean duration of mating events involving sterile (94.1 ± 3.59 min) and transgenic males (81.1 ± 3.54 min) were both significantly shorter than for wild males (123.3 ± 1.93 min). Further investigation is suggested to assess other behavioral parameters, such as the amount of sperm transferred by transgenic males, their ability to disperse and survive in the field conditions, and their capacity to prevent females remating with wild males, in order to determine the potential of this transgenic strain for inclusion in the Brazilian SIT programs.

One new genus, two new species and two new records of Eriophyidae from Vietnam (Acari: Eriophyoidea)

ABSTRACTTo date, only three eriophyoid species have been reported from Vietnam. In this article, we described and illustrated a new genus, two new species and two new records of eriophyoid mites from Vietnam. One species is Dorsisulcatus hsienmus gen. nov. & sp. nov., which infests Burretiodendron hsienmu W.Y. Chun & F.C. How (Malvaceae). The mite seems to be vagrant and no visible symptoms were observed on the leaf surfaces. The other mite species is Shevtchenkella longitubercula sp. nov., which resides on the undersurface of Dimocarpus longan Lour. (Sapindaceae) leaves. The presence of numerous mites did not produce visible symptoms nor the presence of rust on the leaf undersurface. Furthermore, Neometaculus catappiae Huang and Tegonotus evodiae Wei were recorded in Vietnam for the first time.http://zoobank.org/urn:lsid:zoobank.org:pub:A088EBF8-D98B-47F5-8B6E-36406C143FEC

Two new taxa of Nymphaea (Nymphaeaceae) from Manipur, India

Two new taxa of Nymphaea, Nymphaea manipurensis and N. manipurensis var. versicolor are described from Manipur, India. They resemble N. tetragona Georgi in their tetragonal-shaped receptacle, but are easily distinguished from the latter by their partial apocarpy. In being partly apocarpous and having purplish leaf undersurfaces and erect rhizomes, they are similar to N. nouchali Burm. f. A comparison of these two taxa with N. nouchali is provided, along with a key to all Nymphaea known from India. The two new taxa have very similar characters, but differ in minor characteristics, and thus one is treated as a variety of the new species.

NewQuercus-feedingBrevulacusspecies, redescription ofRhyncaphytoptus cerrifoliaeFarkas and new Eriophyoid mite records from Hungary (Acari: Prostigmata: Eriophyoidea)

Author made regular mite collectings between 1990 and 2010 on ornamental trees and shrubs, on streets, parks, in city greenery, forests, botanical gardens and private gardens, in various localities of Hungary. During this survey a new Quercus-infesting eriophyoid mite species was collected: Brevulacus carpathicus n. sp. is described and illustrated from Quercus petraea. Rhyncaphytoptus cerrifoliae Farkas is redescribed from Quercus cerris. Both species produce wax and are vagrant on the leaf undersurface. Two other species, viz. Aceria cichorii Petanovic, Boczek et Shi and Cecidophyes tristernalis (Nalepa) are new species for the fauna of Hungary. Some faunistic data on the known taxa from this country are included.

First Report of Plasmopara obducens on Impatiens walleriana in Serbia.

In May 2010, Impatiens walleriana plants with single or double flowers that were showing symptoms resembling those of downy mildew were collected in a greenhouse in the vicinity of Mionica, Kolubara District, Serbia. Diseased plants were severely stunted, with mild inconspicuous mottling and yellowing on the upper surface of the leaves. The lower surface of the affected leaves was completely covered with distinctive thick, white fungal-like growth. Symptomatic leaves wilted very quickly and premature leaf fall was common, leaving plants with only a few of the youngest leaves and no or few and poorly developed flowers. Disease incidence was extremely high, approaching 100%, and wilting and collapse of affected plants was very rapid, resulting in losses of more than 90%. White downy growth developing on leaf undersurfaces consisted of hyaline, thin-walled sporangiophores with monopodial branching and numerous, ovoid and hyaline sporangia. Apical branchlets of sporangiophores were at right angles to the main axis, with no apical thickening. Downy mildew of impatiens can be caused by Plasmopara obducens or the less known Bremiella sphaerosperma. The two can be differentiated on the basis of symptomatology and morphology of sporangiophores (1). The absence of well-defined spots on the infected impatiens leaves and straight sporangiophores indicated that the pathogen was P. obducens, which was further supported by molecular identification. Total DNA was extracted directly from plant tissue with a DNeasy Plant Mini Kit (Qiagen, Hilden, Germany) following the manufacturer's instructions, and the 5'-end of the nuclear DNA coding for the large ribosomal subunit (LSU rDNA) was amplified by PCR using primers NL1 and NL4 (3). Each PCR amplification yielded two bands estimated at 800 and 650 bp, respectively. A representative isolate, 28-10, was sequenced and 727 bp of the larger band (GenBank Accession No. HQ246451) were found to be identical with P. obducens isolate (AY587558) from the United Kingdom. The sequence was almost identical with those of three P. obducens isolates deposited in NCBI GenBank: EF196869 and AY035522 differed from it by one base pair and FJ787308 by two base pairs. The sequence (HQ223336) of the smaller band was identical to that of three Impatiens accessions (AY727936, AF479154, and AY056515). Pathogenicity tests included inoculation of young I. walleriana plants by spraying with a sporangial suspension. The inoculated plants were kept in experimental chambers at 20°C and 80 to 90% relative humidity, and downy mildew symptoms were observed after 13 to 15 days. To our knowledge, this is the first report of downy mildew of I. walleriana caused by P. obducens in Serbia. So far the presence of P. obducens was recorded in Bulgaria, the Czech Republic, Denmark, Finland, Lithuania, Romania, Russia, the United Kingdom (2), and recently in Norway (4). Thorough inspection would be needed to determine the distribution and incidence of P. obducens on impatiens in Serbia both indoors and outdoors. Impatiens is one of the most popular ornamentals in Serbia and intensive and increasing production may be seriously endangered by the presence of P. obducens.

Two new genera and four new species of Eriophyoid mites (Acari: Eriophyoidea) from sub-Himalayan West Bengal, India

ABSTRACT Two new genera and four new species of Eriophyoidea are described and illustrated from sub-Himalayan West Bengal, India. Tergamplum callicarpi n. gen., n. sp. was found free living on leaf undersurfaces of Callicarpa longifolia Lam. (Verbenaceae); Ashieldophyes glochidionae n. sp. and Isoannulus bengalensis n. gen., n. sp. were found free living on leaf undersurfaces of Glochidion multiloculare (Rottler ex Willd.) Voigt (Euphorbiaceae), and Vimola guajavae n. sp. was found free living on leaf undersurfaces of Psidium guajava L. (Myrtaceae).

A Comparison of Leaf Physiology and Anatomy of Two Himalayan Oaks in Response to Different Light Environments

Leaf physiological and anatomical attributes of seedlings of two Himalayan oaks grown in different light conditions were examined. Both species are stand forming with banj oak (Quercus leucotrichophora) dominating at elevations of 1400–2300 m whereas tilonj oak (Quercus floribunda) is common from 2100–2700 m altitudes. Both oaks are hypostomatous and have sclerophyllous leaves. While Q. leucotrichophora oak leaves were larger, those of Q. floribunda were thicker and more densely packed leaves. At the seedling stage, the points of Q. floribunda leaves are modified into spines apparently to reduce herbivory. Q. leucotrichophora leaves have a thick cuticle, and presence of stellate epidermal hair on the leaf undersurface to reduce transpiration. Quercus floribunda seedlings had anatomical traits consistent with more efficient use of light but lower water use efficiency. Contrary to prevailing belief, Q. floribunda leaves had a higher photosynthetic rate at all light levels and an exploitative strategy that enables it to utilize high moisture and light levels better than Q. leucotrichophora. The ability of Q. leucotrichophora to use water more conservatively is likely to allow it to colonize drier habitats. These observations correlate well with observations of growth and survival on the field.

Nest Sanitation in Social Spider Mites: Interspecific Differences in Defecation Behavior

AbstractNest sanitation behavior is an important adaptation in nest‐building animals. The social spider mite Stigmaeopsis miscanthi (Saito) constructs woven nests on the leaf undersurface of perennial pampas grass (Miscanthus sinensis Anderss) and lives in the nests in large groups. Nest members of this species defecate at only one site inside the nest for nest sanitation, and the waste management is maintained by volatile chemical and tactile cues. Other members of the genus Stigmaeopsis Banks also construct woven nests, live in groups, and manage their fecal wastes, but the species differ in nest and group size, host plant, and social behavior. We investigated the details of waste management in four Stigmaeopsis spp. and found differences in the location of the defecation site and in the way each species recognizes this site. Like S. miscanthi, Stigmaeopsis longus defecates at only one site and uses volatile chemical and tactile cues, whereas Stigmaeopsis takahashii and Stigmaeopsis saharai both defecate at two sites and use only tactile cues. We discuss the reasons for the waste management differences within the genus, and the relationship between the means of waste management, nest and group size.

A NEW SPECIES OF DISSOCHAETA BLUME (MELASTOMATACEAE) FROM KALIMANTAN (BORNEO, INDONESIA)

Dissochaeta atrobrunnea (Melastomataceae–Dissochaeteae) from Kalimantan (Borneo, Indonesia) is described and illustrated. The species can be assigned to Dissochaeta sect. Dissochaeta and is easily recognized by its dense cover of light brown, sessile, stellate hairs and dark brown, 4–6 mm long bristles on branches, leaf undersurfaces, petioles, inflorescences, bracts and hypanthia. Like all other species of Dissochaeta sect. Dissochaeta, D. atrobrunnea shows heterantherous flowers.

Distribution of the Predatory Mite Typhlodromus pyri (Acari: Phytoseiidae) on Different Apple Cultivars

The effect of apple cultivar on the distribution of the predatory mite Typhlodromus pyri was studied in an experimental orchard where spider mites occurred at negligible densities. Seven apple scab-resistant cultivars, showing some differences in their leaf morphology, were considered. In particular, their leaf blade was classified according to four levels of pubescence. The distribution of T. pyri along the shoots was also studied. In the first experimental year the colonization of different cultivars by T. pyri showed definite patterns, sometimes influenced by the occurrence of eriophyids. One year later, T. pyri abundance again showed some differences among cultivars in conditions of prey scarcity. In both years large phytoseiid populations were recorded on the cultivar N.Y. 18491, despite the low eriophyid occurrence, probably because of its highly pubescent leaf undersurfaces. In contrast, Prima and TSR 29T219, characterized by slightly pubescent leaf undersurfaces, supported low phytoseiid densities independently of prey availability.

Distribution and sampling of the whiteflies Aleurothrixus floccosus, Dialeurodes citri, and Parabemisia myricae (Homoptera: Aleyrodidae) in citrus in Spain.

From 1993 to 1995 data sets were collected from four citrus groves in Valencia, Spain, to determine the distribution patterns of eggs and nymphs of Aleurothrixus floccosus (Maskell), Dialeurodes citri (Ashmead), and Parabemisia myricae (Kuwana) on leaves, and to develop reliable sampling plans for estimating densities of immature whiteflies. A. floccosus showed higher aggregation than the other two species. The dispersion index b from the Taylor power law did not vary between different developing stages for A. floccosus and D. citri, reaching overall values of 1.70 and 1.53, respectively. In P. myricae, b was 1.60 for eggs and N1, and 1.46 for the remaining nymphs. The minimum number of leaves to estimate the population density with a coefficient of variation of 0.25 for densities above 10 immature whiteflies per leaf was 40 for D. citri and P. myricae, and 250 for A. floccosus. Binomial sampling programs for the three species were rejected for pest management purposes due to the high sample sizes required. The enumerative procedure of counting the number of insects per leaf appears to be the most suitable method for D. citri and P. myricae. For A. floccosus an index of occupation (from 0 to 10) linearly related to the proportion of the leaf undersurface occupied by this insect was found to be reliable and time-saving. Examining 150 leaves with this index achieves the desired relative variation level of 0.25 for most population densities usually found in commercial groves.

Effects of irradiance and spectral quality on leaf structure and function in seedlings of two Southeast Asian Hopea (Dipterocarpaceae) species

We studied the development of leaf characters in two Southeast Asian dipterocarp forest trees under different photosynthetic photon flux densities (PFD) and spectral qualities (red to far-red, R:FR). The two species, Hopea helferi and H. odorata, are taxonomically closely related but differ in their ecological requirements; H. helferi is more drought tolerant and H. odorata more shade tolerant. Seedlings were grown in replicated shadehouse treatments of differing PFD and R:FR. We measured or calculated (1) leaf and tissue thicknesses; (2) mesophyll parenchyma, air space, and lignified tissue volumes; (3) mesophyll air volumes (V(mes)/A(surf)) and surfaces (A(mes)/A(surf)); (4) palisade cell length and width; (5) chlorophyll/cm and a/b; (6) leaf absorption; and (7) attenuance/absorbance at 652 and 550 nm. These characters varied in response to light conditions in both taxa. Characters were predominantly affected by PFD, and R:FR slightly influenced many characters. Leaf characters of H. odorata were more plastic in response to treatment conditions. Characters were correlated with each other in a complex fashion. Variation in leaf anatomy is most likely a consequence of increasing leaf thickness in both taxa, which may increase mechanical strength and defense against herbivory in more exposed environments. Variation in leaf optical properties was most likely affected by pigment photo-bleaching in treatments of more intense PFD and was not correlated with A(max). The greater plasticity of leaf responses in H. odorata helps explain the acclimation over the range of light conditions encountered by this shade-tolerant taxon. The dense layer of scales on the leaf undersurface and other anatomical characters in H. helferi reduced gas exchange and growth in this drought-tolerant tree.

New Taxa and Nomenclatural Notes on the Flora of the Marojejy Massif, Madagascar: II. Anacardiaceae: A New Species of Campnosperma

A new species of the genus Campnosperma, previously considered to contain only a single species in Madagascar, is described from the Massif de Marojejy in northeastern Madagascar. Campnosperma parvifolium differs from C. micranteium in its smaller leaves, with fewer secondary veins, and sparsely but evenly lepidote leaf undersurface. It occurs on high mountain ridges at Marojejy and Anjanaharibe, while C. micranteium is a species found on sand in littoral forests. The Massif de Marojejy in northeast Madagascar, in the province of Antsiranana, has always been of great interest botanically (Humbert, 1955), but recent intensive collecting has yielded a variety of new species (Miller, 1998; Miller & Pipoly, 1993). Campnosperma, a genus of Anacardiaceae with perhaps a dozen species in tropical America, Madagascar, the Seychelles, tropical Asia, and the western Pacific, has been previously considered to consist of only a single species in Madagascar, Campnosperma micranteium L. March (Perrier de la Bathie, 1946). The species are trees having leaves with lepidote scales, unisexual flowers with twice as many stamens as petals, and a 2-celled drupe. Rend Capuron had reviewed the herbarium material from Madagascar in the herbarium of the Laboratoire de Phandrogamie, Museum National d'Histoire Naturelle (P) and annotated the specimens, recognizing several infraspecific taxa, but his results were never published. Examination of the presently available collections of Campnosperma indicates that the variation presented is much too significant to be accounted for by a single species (Miller & Randrianasolo, in prep.). One population that is particularly distinct is the following new species. Campnosperma parvifolium R. Capuron ex J. S. Miller & A. Randrianasolo, sp. nov. TYPE: Madagascar. Antsiranana: Reserve Naturelle Marojejy, along the trail to the summit of Marojejy Est, below the third camp, lichen forest and exposed wind-swept ridges, elev. 1100-1300 m, 14?26'S, 49015'E, 10 Oct. 1988, James S. Miller et al. 3529 (holotype, MO 5067322; isotypes, G, K, NY, P, TAN, TEF, US). Figure 1. Arbor parva vel frutex, 2(10-12) m alta. Folia persistentia, coriacea; lamina elliptica ad obovata (1.4-)2-6.7 cm longa, (0.9-)1.5-3.3 cm lata, apice retusa ad rotundata, basi obtusa ad cuneata, pagina inferiore glabra vel sparsim stellata, lepidota. Inflorescentiae racemosae ad paniculatae, (1-)3.3-6.3 cm longae. Flores unisexuales, gemmae 1 mm longae. Fructus drupaceus, ellipsoideus, 7-9 mm longus, 5-7 mm latis, glabratus. Small tree or shrub 2(10-12) m tall, the young twigs densely covered with a mixture of lepidote scales and stellate hairs, later glabrescent and smooth or somewhat waxy. The leaves persistent, coriaceous; blades elliptic to obovate, (1.4-)2-6.7 cm long, (0.9-)1.5-3.3 cm wide, the apex retuse to rounded, the base obtuse to cuneate, sometimes briefly decurrent along the petiole for ca. 1-2 mm, the margin strongly revolute, entire, the adaxial surface glabrous, waxy, and lustrous, sometimes sparsely lepidote, the abaxial surface glabrous or occasionally with sparse stellate hairs, evenly lepidote (appearing gland-dotted), but the scales not overlapping, the venation brochidodromous, prominent, and raised on both surfaces, the secondary veins 5-9, parallel, often only slightly more prominent than the dense reticulum of tertiary veins on the lower surface; petioles 3-8 mm long, stout, canaliculate on the adaxial surface, lepidote to densely stellate-pubescent. Inflorescences borne in the upper leaf axils, sparsely branched panicles or racemes (1-)3.3-6.3 cm long, the branches evenly to densely lepidote to stellate, each flower subtended by a triangular bract 0.5-1 mm long. Flowers unisexual, the plants functionally dioecious, with reduced anthers in female flowers and reduced ovaries in male flowers, small, 1 mm long in bud, 34 mm diam. when open, on pedicels 0.5-1.5 mm long, ca. 1 mm diam.; sepals 4, imbricate, deltate, ca. 0.5 mm long, lepidote; petals 4, imbricate, broadly elliptic, 1-2 mm long, ca. 1 mm wide, glabrous or with an occasional lepidote scale on the exterior surface; stamens 8, the filaments inserted at the base of the disc, flattened and broader at the base, ca. 0.5 mm long, the anthers ca. 0.2 mm long; nectariferous disc annular and unevenly lobed; ovary ovoid, small, and partially immersed in the anNovoN 8: 170-172. 1998. This content downloaded from 207.46.13.164 on Mon, 27 Jun 2016 05:35:39 UTC All use subject to http://about.jstor.org/terms Volume 8, Number 2 1998 Miller & Randrianasolo 171 Campnosperma parvifolium from Madagascar

Leaf Domatia and the Distribution and Abundance of Foliar Mites in Broadleaf Deciduous Forest in Wisconsin

-Leaf domatia occur frequently in vein axils on the leaf undersurface of many woody Dicotyledonae in the broadleaf deciduous forests of the northern hemisphere. These structures are often used by mites for shelter and as sites for egg laying. Taxa of predatory and fungivorous mites and sometimes of herbivorous mites were associated with the domatia of six species of trees or woody vines (Quercus velutina, Q. rubra, Acer saccharum, Prunus virginiana, P serotina and Vitis riparia) examined near LaValle in S-central Wisconsin. Comparisons of mite frequency and abundance in different leaf microhabitats (in domatia, in major vein axils without domatia, along the midrib, and on the leaf lamina) showed that mites respond strongly to leaf architectural features, especially domatia. Further, mite evidence was more frequent or mites more abundant on leaves of species with domatia in four of five paired-species comparisons. The abundance of potentially beneficial mites, primarily Metapronematus leucohippeus (Tydeidae) and Typhlodromus nr. pomi (Phytoseiidae) was significantly greater and the overall ratio of beneficial to herbivorous mites was greater on leaves of species with domatia. Leaf domatia are important shelters for potential plant mutualists and alter the distribution and abundance of foliar mites in the canopy of temperate broadleaf

Hybridization in the Catalina Island Mountain Mahogany (Cercocarpus traskiae): RAPD Evidence

The Catalina Island mountain mahogany is one of 10 species of shrubs and small trees (Lis 1992) comprising the genus Cercocarpus H. B. K (Rosaceae). Species in the genus are widely distributed throughout western North America and are delimited primarily on the basis of leaf characteristics (Mortenson 1973; Lis 1992). The Catalina Island mountain mahogany (C. traskiae Eastwood) is one of the most distinctive species in the genus due to its thick, coriaceous leaves and woolly pubescence on the leaf undersurface. The species is extremely rare, restricted to Wild Boar Gully on the southwest side of Santa Catalina Island in the Channel Islands off the coast of California (Fig. 1). When the population was first discovered in 1897, it consisted of over 40 individuals (Thorne 1967). Due to overgrazing by introduced mammalian herbivores (Coblentz 1980; Hobbs 1980), however, the population has been greatly reduced (Rieseberg et al. 1989). Cercocarpus traskiae is listed as endangered by the state of California and thus is afforded protection by California law (Smith & Berg 1988). Inexplicably, the species is not listed as endangered or threatened by the U.S. Fish and Wildlife Service, although it is under consideration for listing. In the late 1970s a detailed inventory of the Wild Boar Gully population was undertaken, and a total of eight Cercocarpus trees were discovered and tagged (Martin 1984). In addition, two of the trees (A, B; Fig. 1) were fenced to protect them from herbivores, and in 1985 the Catalina Conservancy constructed a larger fence around an area that included both trees, as well as about an acre of good habitat. The fencing effort was extremely successful, and by 1988 approximately 70 seedlings were observed within the fenced area (Rieseberg et al. 1989). Unfortunately, several of the adult plants resembled the island mountain mahogany, Cercocarpus betuloides Torrey & A. Gray var. blancbeae (C. Schneider) Little, in key morphological features such as leaf pubescence and leaf thickness or were immediate for these characters (descriptions of both species are given by R. Lis in Hickman [1993]). Cercocarpus betuloides var. blancbeae is only slightly more widespread than C traskiae, occurring on all of the Channel Islands except San Clemente. But the species is much more abundant than C traskiae on Santa Catalina and is known to occur in adjacent canyons, so the possibility of hybridization between the two species could not be dismissed. Furthermore, it is suspected that some of the seedlings might be of hybrid origin (T. Martin, personal communication). In an attempt to clarify the identity of morphologically ambiguous individuals, Rieseberg et al. (1989) undertook a study of allozymic variation and leaf anatomy of all the adult mahogany trees discovered in Wild Boar Gully. Of the eight adult trees in the Gully, three were anatomically intermediate between C. traskiae and C betuloides var. blancbeae, suggestive of hybridization. Analysis of 17 isozyme loci in C traskiae, as well as a nearby population of C betuloides var. blancbeae (Fig. 1), revealed one diagnostic isozyme polymorphism differentiating the two species. Based on this single isozyme polymorphism, five of the eight trees were diagnosed as C traskiae, one as C betuloides var. blancbeae, and two as hybrids. However, isozyme analyses of the 28 seedlings large enough to survive the loss of a single leaf revealed all to be pure C traskiae. The results from this study were not entirely satisfactory, however, because the classification of individuals as parental versus hybrid was based on a single locus. The use of a single diagnostic locus can ensure the correct identification of first-generation hybrids, but F2or later-generation hybrid or backcross progeny could easily be misdiagnosed as belonging to one of the parental classes. Thus, it was not surprising that two of the plants lacking a hybrid enzyme genotype were anatomically Paper submitted April 1994; revised manuscript accepted July 15, 1994.

Poinsettia (Euphorbia pulcherrima Willd Ex Koltz) Cultivar-Mediated Differences in Performance of Five Natural Enemies of Bemisia argentifolii Bellows and Perring, n. sp. (Homoptera: Aleyrodidae)

Abstract Laboratory evaluations of five natural enemies of the silverleaf whitefly, Bemisia argentifolii Bellows and Perring, n. sp., were conducted to determine their potential as biological control agents in greenhouse poinsettia ranges. Adult longevity, prey consumption or host feeding and parasitism rates, and parasitoid emergence were measured for one predator, Delphastus pusillus LeConte, and four parasitoids, Encarsia formosa Gahan, Encarsia luteola Howard, Encarsia pergandiella Howard, and Encarsia transvena (Timberlake), as possible indicators of efficacy. Characterization of each parameter was performed on two poinsettia cultivars: the first, ′Annette Hegg Brilliant Diamond,′ has trichome densities on the leaf undersurfaces approximately 15% less than the trichome densities on the leaf undersurfaces of the second cultivar, ′Lilo.′ Adult longevity varied significantly between natural enemies (ranging from an average high of 85.2 days for female D. pusillus feeding on B. argentifolii nymphs to an average low of 2.8 days for the Canada colony of E. formosa), but not between cultivar. Prey consumption and oviposition by D. pusillus varied between prey type (nymphs consumed > eggs consumed) and poinsettia cultivar (′Annette Hegg Brilliant Diamond′ > ′Lilo′). Host feeding, parasitism and total number of B. argentifolii nymphs killed varied significantly among Encarsia spp., but no single wasp performed better than the rest across all three parameters. Host feeding, parasitism, and total number of nymphs killed were greater on ′Annette Hegg Brilliant Diamond′ than on ′Lilo′ and this difference was consistent among the four parasitoid species. Among parasitoid species differences in percentage emergence were consistent between the two poinsettia cultivars with emergence from parasitized nymphs on ′Lilo′ being greater than emergence on ′Annette Hegg Brilliant Diamond.′ Results from these evaluations suggest that the probability of achieving successful augmentative biological central will be greater on poinsettia cultivars with fewer trichomes. In addition, achieving biological control is likely to be difficult with releases of E. transvena, but a greater chance for success may be possible through releases of D. pusillus when whitefly densities are high or through releases of E. formosa (Beltsville colony) or mated E. pergandiella independent of whitefly densities.

Peronospora ficariae . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Peronospora ficariae . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Anemone coronaria, Helleborus purpurascens, Ficaria calthifolia, F. ledebourii, F. ficarioides, Ranunculus abortivus, R. acriformis, R. acer, R. acris, R. alpestris, R. auricomus, R. bulbosus, R. carpaticus, R. cassubicus, R. constantinopolitanus, R. crenatus, R. fascicularis, R. ficaria (= Ficaria verna ), R. flammula subsp. flammula, R. languinosus, R. lateriflorus, R. lingua, R. montanus, R. nemorosus, R. oreophilus, R. oxyspermus, R. pedatus, R. pennsylvanicus, R. platanifolius, R. polyanthemus, R. pseudoplatanus, R. recurvatus, R. repens, R. sardous, R. scleratus, R. septentrionalis, R. uncinatus (= R. bongardi ), R. velutinus . DISEASE: Downy mildew of Ranunculus species, covering the entire leaf undersurface. GEOGRAPHICAL DISTRIBUTION: Asia-Temperate: China, Kazakhstan, Kirgizistan, Russia (Kamchatka), Stavropol, Japan. Australasia: New Zealand. Europe: Austria, Belgium, Belorussiya, Bulgaria, Czechoslovakia, Denmark, Eire, Estonia, Faeroes, Finland, France, Germany, Hungary, Iceland, Italy, Latvia, The Netherlands, Norway, Poland, Romania, Russia (Krym, Moscow, Pskov, Novgorod, St. Petersburg, Saratov, Smolensk, Tambov, Tatariya, Tula, Yaroslavl) Sweden, Switzerland, Ukraine, UK (England, Scotland, Wales, Channel Islands), Yugoslavia. North America; Canada (British Columbia, Que), USA (Alabama, Idaho, Maine, Michigan, Oregon, Wisconsin, Washington State, Wyoming, New York). South America: Argentina, Dominican Republic. TRANSMISSION: By conidia dispersed by wind or rain-splash. The role of oospores in disease transmission is unknown, although they may act as perennating structures.

Distribution of Immature Atrichopogon wirthi (Diptera: Ceratopogonidae) on Leaves of the Water Lettuce, Pistia stratiotes

The immature stages of Atrichopogon wirthi Chan and Linley are found mostly on the lower surfaces of more mature leaves of the water lettuce, Pistia stratiotes L. Eggs, first instars, and pupae are found only on the leaf undersurface, while second to fourth instars may occur also on top of the leaf. Eggs are laid mostly in the large undersurface grooves 1–11 cm above the wet–dry line (most from 5–10 cm). First instars are found close to the eggs, on the distal third of the leaf. Second instars are more widely distributed, with the majority situated around or just above the wet–dry line, and with occasional individuals 1–10 cm above it. Third and fourth instars also occur mainly around the wet–dry line (0.5 cm below to 4 cm above). Pupae are distributed more distally, 3–9 cm above the wet–dry line. Pistia plants examined between July and October 1987 yielded an average of 28.3 unhatched (presumably viable) eggs, 4.5 first, 2.5 second, 1.8 third, and 2.4 fourth instars, 2.3 pupae, and 2.8 pupal exuviae per plant. Certain inferences concerning the life history and behavior of A. wirthi are discussed