Cut Twigs Research Articles

Establishing the twig method for investigations on pollen characteristics of allergenic tree species

The twig method in climate chambers has been shown to successfully work as a proxy for outdoor manipulations in various experimental setups. This study was conducted to further establish this method for the investigation of allergenic pollen from tree species (hazel, alder, and birch). Direct comparison under outdoor conditions revealed that the cut twigs compared to donor trees were similar in the timing of flowering and the amount of pollen produced. Cut twigs were able to flower in climate chambers and produced a sufficient amount of pollen for subsequent laboratory analysis. The addition of different plant or tissue fertilizers in the irrigation of the twigs did not have any influence; rather, the regular exchange of water and the usage of fungicide were sufficient for reaching the stage of flowering. In the experimental setup, the twigs were cut in different intervals before the actual flowering and were put under warming conditions in the climate chamber. An impact of warming on the timing of flowering/pollen characteristics could be seen for the investigated species. Therefore, the twig method is well applicable for experimental settings in pollen research simulating, e.g., accelerated warming under climate change.

Chilling and Forcing From Cut Twigs-How to Simplify Phenological Experiments for Citizen Science.

Low-cost phenological experiments with cut twigs are increasingly used to study bud development in response to spring warming and photoperiod. However, a broader variety of species needs to be tackled and in particular the influence of insufficient winter chilling deserves more attention. Therefore, we investigated if and how chilling requirements can be efficiently investigated by cut twigs and how this low-tech approach could be successfully implemented as a citizen science or school project. We conducted an experiment on bud burst and leaf development of Corylus avellana L. twigs, with natural chilling outdoors on a shrub (S) and another chilling treatment as cut twigs in containers (C), and subsequent forcing indoors. Subsampling of the number of cutting dates and number of twigs was used to infer minimum required sample sizes. Apart from insufficiently chilled twigs, ~80% of the twigs (both S and C) reached leaf out. For multiple definitions of chilling and forcing, a negative exponential relationship was revealed between chilling and amount of forcing needed to reach certain developmental stages. At least 5 out of 15 cutting dates or alternatively half of the 10 twig repetitions, but especially those mirroring low chilling conditions, were needed to describe the chilling-forcing relationship with some degree of robustness. In addition, for cutting dates with long chilling, i.e., from January onwards, freshly cut twigs (S) required significantly more forcing to reach bud burst than twigs from containers (C), although the effect was small. In general, chilling conditions of mature shrubs were well captured by cut twigs, therefore opening the possibility of chilling through refrigeration. We conclude that experimental protocols as outlined here are feasible for citizen scientists, school projects, and science education, and would have the potential to advance the research field if carried out on a large scale. We provide an easy-to-use Shiny simulation app to enable citizen scientists to build up a bud development model based on their own experimental data and then simulate future phenological development with winter and/or spring warming. This may encourage them to further study other aspects of climate change and the impacts of climate change.

Tenuazonic acid-induced change in volatile emission from rose plants and its chemometrical analysis

This study investigated changes in volatile organic chemicals (VOCs) of rose plants (Rosa chinensis Jacq.) after treatment with tenuazonic acid (TeA). TeA is a toxin produced by Alternaria alternata (Fr.) Keissler and is a key virulence factor for infection of the plants by the fungus. VOCs were collected in situ separately from intact live twigs of healthy and TeA-treated rose plants by dynamic headspace adsorption (DHSA) or from cut twigs of healthy and treated roses by headspace solid-phase microextraction (HS-SPME) and identified by gas chromatography–mass spectrum (GC–MS). VOC emissions changed significantly after the plants were treated with TeA based on the results obtained with both methods. GC–MS and chemometrical analysis show that the content of monoterpenes significantly increased the most, followed by ketones and alcohols, whereas sesquiterpenes decreased significantly, resulting from the induction by TeA. Twelve VOCs were emitted at significantly higher or lower levels from TeA-treated roses compared with healthy roses. After TeA treatment, the content of 4-hydroxy-4-methyl-2-pentanone increased by 80.1% (DHSA) and 67.8% (HS-SPME) while β-elemene decreased by 84.93% (DHSA) and 71.21% (HS-SPME). Butyl acetate, allo-ocimene, decanol and tetradecanol with their relatively large contents were detected only from TeA-treated roses as early as 2–4 days after treatment with TeA. This means that theses VOCs could be used as the markers for the detection of the fungus infection in rose plants before disease symptoms become visible. The obvious temporal effects of the changes in contents of these four VOCs were also recorded. The results will help to understand the chemical mechanisms of indirect plant-mediated interactions between phytopathogens and herbivorous insects in the ternary systems.

Non-foraging tool use in European Honey-buzzards: An experimental test.

Examples of tool-use behaviors by birds outside foraging contexts are scarce and limited to a handful of species. We report a field experiment aimed to test whether an observed suite of odd behaviors by European Honey-buzzards (Pernis apivorus) represents use of green twigs cut from trees and woody shrubs as a tool to attract ants for anting. Specifically, we tested whether buzzards are selective in their choice of twigs, under the assumption that birds would prefer easy-to-collect twigs from plants that effectively attract ants. Experimental results lend support to our hypothesis that European Honey-buzzards cut green twigs of Montpellier maple trees (Acer monspessulanum) and, to a lesser extent, of Pyrenean oaks (Quercus pyrenaica) for their immediate use as ant attractors. Fresh twigs of both tree species attracted large numbers of ants, suggesting that their preferential use in the reported behavior of Honey-buzzards is not a random selection of the available plant material. Maple twigs, however, were the easiest to break and oak twigs the hardest compared to other plants in the community. This suggests that the relative ease of cracking of maple twigs may account for the preference Honey-buzzards have for this plant species as compared with Pyrenean oak, whose twigs demand considerable more effort from the birds to break. Our results lend support to the inclusion of the reported behavioral sequence by this raptor species as a potential example of tool use in birds outside the usual foraging context.

BIOECOLOGIA DE <i>Oncideres cervina</i> (COLEOPTERA: CERAMBYCIDAE) EM CANELA-GUAICÁ (<i>Ocotea puberula</i>: Lauraceae) NA REGIÃO CENTRAL DO RIO GRANDE DO SUL, BRASIL

http://dx.doi.org/10.5902/1980509818466O conhecimento da entomofauna dos ecossistemas florestais tem sua importância no que se refere aos danos provocados pelos seus diferentes segmentos. Estudou-se a bioecologia do serrador Oncideres cervina (Coleoptera: Cerambycidae), em Ocotea puberula (Lauraceae), na região central do estado do Rio Grande do Sul, Brasil. Em 49 galhos cortados foram analisados a frequência de corte, o diâmetro de galhos no corte e secções, comprimento de galhos, frequência de incisões de postura, emergência de adultos, tamanho do orifício de saída, comprimento e volume da galeria larval desta espécie. O período de corte de galhos se estende de fevereiro a março e esta espécie se enquadra como cortadora de galhos grossos. O número de incisões de postura é variável, porém, a maior concentração é encontrada nas secções de 20 a 40 cm a partir do corte, com valor médio de 11 incisões. Duzentos adultos emergiram de 27 galhos, com pico de emergência na primeira quinzena de dezembro. Para completar o seu desenvolvimento, esta espécie requer menor volume de madeira se comparada a outras espécies de serrador.

Attraction Effects to Various Conditions of Pinus koraiensis against Pine Sawyer, Monochamus saltuarius (Coleoptera: Cerambycidae)

Recently, the pine sawyer Monochamus saltuarius has been proved as a vector of pinewood nematode, Bursaphelenchus xylophilus in South Korea. This pest causes serious concern that widely distributed in the middle of South Korea and most likely to spread fast. To understand their ecological behavior, the attraction behavior of the pine sawyer was tested in the volatile samples of Pinus koraiensis by emitting different host condition. The olfactory response of the immature (0∼3 days old after emergence) adults of M. saltuarius preferred the volatiles from the fresh host condition (fresh twigs, just cut twigs which wrapped with the parafilm), whereas the mature (20∼30 days old) adults preferred the volatiles from the 3-day old stressed host (twigs infested by male and female, 3-day old cut twigs that were artificially damaged). In the GC and GC/MS analyses, contrary to the samples from the fresh host condition having monoterpene volatiles only, the samples from the 3-day old stressed host were revealed to have more volatiles of oxygenated monoterpenes and sesquiterpenes. The attraction assay of M. saltuarius adults to the volatile mixtures of monoterpenes, oxygenated monoterpene, and sesquiterpene appeared to be efficient when the oxygenated monoterpene mixture was necessarily treated with monoterpene mixtures.

A checklist of intercepted whiteflies (Hemiptera: Aleyrodidae) at the Republic of Korea ports of entry

Twelve species of whiteflies were intercepted in quarantine at Korean ports of entry on cut flowers, cut twigs, seedlings and trees from China, Japan, India, Malaysia, Sri Lanka, Thailand, Vietnam, Netherlands, Uzbekistan, Australia, New Zealand, and USA. This checklist and illustrative photographs are provided to assist in identifying intercepted specimens of whiteflies.

Host choice and host leaving in Rhopalosiphum padi (Hemiptera: Aphididae) emigrants and repellency of aphid colonies on the winter host

Host choice and winter-host leaving in emigrants of bird cherry-oat aphid, Rhopalosiphum padi (Linnaeus), were investigated in the laboratory. In settling choice tests, emigrants collected from the winter host, Prunus padus, preferred this plant over a summer host, oats. Emigrants which had left P. padus for up to 24 h did not express a preference as a group, and those which had left for 24-48 h preferred oats. Eighty seven percent of emigrants caged as fourth-instar nymphs on P. padus leaves abandoned the host by the second day of adult life, and apparently did not subsequently return to the leaf. In an olfactometer, P. padus leaves which had supported spring generations of R. padi were repellent to emigrants. Volatiles were entrained from uninfested and R. padi-infested P. padus using cut twigs in the laboratory as well as intact twigs on a tree in the field. Entrainment extracts from uninfested P. padus had no effect on emigrants in the olfactometer, whereas those from twigs infested with nymphal emigrants were repellent. The study indicates that in R. padi, host-alternation is driven by behavioural changes which occur in individuals as well as between morphs.

Conidial Morphology, Pathogenicity and Culture Characteristics of Phomopsis Isolates from Peach, Japanese Pear and Apple in Japan.

To classify Phomopsis isolates from fruit trees, we examined their conidial morphology, pathogenicity and culture characteristics. Two types of colony, designated W and G, were recognized among Phomopsis isolates from peach, Japanese pear and apple. These types of isolates were not correlated with their original hosts. The lengths of alpha conidia were similar in both W and G type isolates. Both alpha and beta conidia were produced by all isolates of W-type, whereas only alpha conidia were observed in isolates of G-type when cultured on potato dextrose agar at 25°C. In cross-inoculation tests using cut twigs, isolates of both types were pathogenic on other hosts as well as on the original host. In the field inoculation tests, G-type isolates were generally more virulent in twigs or branches of peach, Japanese pear and apple than were W-type isolates. These results suggest that the Phomopsis isolates from peach, Japanese pear and apple are grouped into two specific or infraspecific taxa.

Evaluation of Relative Speed of Incapacitation of Elm Bark Beetle Insecticides, Laboratory Bioassay, 1993

Abstract Branches of Siberian elm were sprayed 17 Aug to point of run-off with insecticides to evaluate their relative speed to incapacitate elm bark beetle adults. High-end labelled rates for foliar application were used for all treatments. Treated branches were collected 23 Aug and 13 Sep and cut twigs placed in petri dishes with beetles. In each trial, elm bark beetles were collected with pheromone-baited Lindgren funnels and placed in groups of 10 in petri dishes and given portions of the treated branches as food. In the first trial 6 replications were used; only 3 were used in the second trial due to declining bark beetle numbers. Mortality and morbidity was assessed at three intervals within 1 DAT. Morbidity was determined as being unable to walk, but still capable of some movement.

Biosynthetic studies on taxol

Abstract

Changes in photosynthetic activity of buds and stem tissues of Fagus sylvatica during winter

The photosynthetic activity of leafless twigs and buds of Fagus sylvatica was determined by in vivo chlorophyll fluorescence from November to May. Measurements were made on the day of sampling, and during exposure to warm temperatures until reactivation was attained. Under the same conditions, bud development and growth were forced by exposure of cut twigs to 25/18° C at long-day conditions, and bud swelling and bud burst were monitored. Winter inactivation of photosynthesis results in a reduction of the photochemical efficiency of PS II, as indicated by lowering of FV/FM, from January through March. The greatest reduction is in cortical chlorenchyma, the least in folded leaflets and primordia of buds. Restoration of photosynthetic activity, brought about by warming, needed 3–4 weeks in cortex and 1–2 weeks in buds during the coldest period of winter. Frequency distributions based on three types of chlorophyll fluorescence transients, defined by quantitative fluorescence parameters, have proved to be a valuable method for a differentiated expression of the unequal functional activation states of parallel samples. The seasonal course of winter inactivation of photosynthesis did not correspond entirely with the depth of bud dormancy as revealed by the forcing treatments; inactivation of photosynthesis may be more closely synchronized with changes in frost hardiness; possible causes are discussed. We suggest, therefore, that a distinction should be made between inactivation of metabolic processes and depth of dormancy, even though these processes are inherently interrelated.

TECHNIQUE FOR MASS REARING CTENARYTAINA THYSANURA (FERRIS AND KLYVER) (HEMIPTERA: PSYLLIDAE)

A mass rearing technique for consistent production of large numbers of Cfenarytaina thysanura for laboratory studies is described. The number of ovarioles of laboratory-reared and field-collected C. thysanura was compared. The boronia psyllid, Ctenaryfaina thysanura (Ferris and Klyver), is an important pest of Boronia megastigma (Nees) (Mensah and Madden, unpubl. data). The psyllid, originally identified in New Zealand on Boronia sp., was thought to be of Australian origin but remained largely unknown prior to commencement of intensive boronia culture. The effects of the infestation on B. megastigma demanded a need for basic biological and behavioural studies including aspects of the insect host plant interaction, the role of exotic and indigenous natural enemies as well as studies determining appropriate methods of control. Such studies required an abundant, reliable and consistent supply of insects of uniform age and bionomic background. Reported here is a mass-rearing method which provided a simple, highly responsive system for the mass production of large numbers of C. thysanura on demand. Mass-rearing trials were conducted in a glasshouse illuminated by a single, Im 40W fluorescent tube with a photoperiod of 12L:12D, thermostatically controlled with a fan heater and air conditioner. Temperature ranged from 18-20°C and relative humidity was between 65-75% as measured by a 7-day recording thermohygrograph. C. thysanura adults were collected in September 1986 from foliage of naturally-infested field-grown boronia at Copping (eastern Tasmania) using a sweeping net. The psyllids were anaesthetised with ether, sexed and the culture established by placing 2 pairs of males and females onto each of 20 potted seedlings of 6-month-old, 10-20 cm-high boronia plants. Each infested plant was inserted into the mouth of an inverted 2L clear plastic soft drink container 30 cm in height and with a diameter of 10 cm and ventilated by means of 2 opposing gauze-covered lox 10 cm windows. The height of the cage could be altered as the infested plant grew by moving it up the supporting sticks inserted into the soil beside the plant. As the basal opening was lifted from the soil, cotton gauze was inserted at the end to prevent entry or escape of insects. After adult emergence, one 6-day-old female from each cage was dissected in water under a binocular microscope. The number of ovarioles from each was recorded and compared with that of the field collected females of the same age. Emergence of F1 offspring commenced 41 d after infestation. The number of eggs within ovarioles of the laboratory reared female did not differ significantly from that of wild females (P>0.05). A number of cage designs have previously been employed for psyllid culture, e.g. cut twigs immersed in glass vials (Van der Merwe 1941), cellulose acetate cylinder cages (Watmough 1968), perforated plastic bags (Annecke and Cilliers 1%3; Moran and Blowers 1%7), and organdie bags (Clark 1962). The advantages of using ventilated plastic cages on potted plants are that they avoid the wilting associated with cut stems (Van der Merwe 1941; Moran and Blowers 1967) and exclude natural enemies and other unwanted insects such as spiders, scales and aphids (Watmough 1968). It provides a more constant environment and optimal conditions for both plant and insect growth and permits direct observation of the insects through the wall of the plastic cages without disturbance. It also overcomes the problem of excessively prolonged instar development encountered by Van der Merwe (1941) and Moran and Blowers (1967). The only problem with our method was that the potted seedling had to be replaced as the numbers of insects increased. This was due to intraspecific competition for food and space and reduced the efficiency of output. When insects were subcultured to new plants on a regular basis, this technique provided a consistent insect population for laboratory studies.

Effects of exogenous ABA on photosynthesis and stomatal conductance of cut twigs from oak seedlings

Effects of exogenous ABA on photosynthesis and stomatal conductance of cut twigs from oak seedlings

Vegetation zonation on a Natal coastal sand-dune system in relation to salt spray and soil salinity

A number of environmental factors across a coastal sand-dune gradient were monitored over a period of several months. Soil salinities were considerably less than those values usually associated with saline soils, and neither soil salinity nor soil moisture individually correlated with the distribution of vegetation. The patterns of both aerial salt spray and short-term windblown sand correlated well with the species distribution. The survival of cut twigs of four dune scrub species placed at different points on the gradient showed that some factor(s) associated with the aerial environment restricted the scrub species to more sheltered positions. Laboratory studies indicated that both physical damage (associated with windblown sand) and salt spray were implicated in the damage suffered by exposed leaves.

Role of Leaves Present on the Stem Cuttings for Vegetative Propagation in Portulaca grandiflora L.

Role of leaves for vegetative propagation in Portulaca grandiflora has been studied. Twigs when either completely buried in soil or without leaves and half buried did not propagate. The number and linear growth of roots, and the new leaves produced depended on the number of old leaves on the cut twigs when planted.

Twig Feeding by the Smaller European Elm Bark Beetle on Different Kinds of Trees1

Compared with the number of cambial punctures chewed by the smaller European elm bark beetle, Scolytus multistriatus (Marsham), on cut twigs of American elm, Ulmus americana L., in a series of twig-feeding tests conducted under variable temperature conditions in laboratory, there was relatively little to no significant increase or decrease in the number of such punctures on the following trees: Siberian elm, Ulmus pumila L.; Vanhoutte' English elm, U. procera Vanhouttei (Schelle) Rehd.; Japanese elm, U. japonica (Rehd.) Sarg.; Buisman selection smoothleaved elm, U. carpinifolia Gleditsch; Augustine ascending elm, U. americana ascendens Slavin F.; slippery elm, U. fulva Micheux; or on Japanese zelkova, Zelkova serrata (Thunb.) Mak. On David hemiptelea, Hemiptelea Davidii (Hance) Planch., there were significantly fewer cambial punctures while on native hackberry, Celtis occidentalis L., and white oak, Quercus alba L., no such punctures occurred.

Plastic Rearing Cage for Maintaining Fresh Conifer Foliage for Insect Rearing

During the course of control investigations on the black-headed budworm, Acleris variana (Fern.), a preliminary difficulty occurred in the mass rearing of budworm larvae under laboratory conditions. In the forest the eggs are laid on the needles of hemlock and balsam fir trees in late summer. The young larvae emerge the following spring and migrate to the growing buds where they commence active feeding. Under laboratory conditions, however, cut hemlock twigs shed their needles in a very few days and thus the budworm eggs are shed with the needles and exposed to desiccation.

ADELGES COOLEY1 GILLETTE (HEMIPTERA, ADELGIDAE) OF THE DOUGLAS FIR IN BRITAIN: COMPLETION OF ITS LIFE CYCLE

SUMMARY Adelges cooleyi is a pest of Sitka spruce, the primary host, and Douglas fir, the secondary host, on the latter of which it has been known in Britain since 1913. Hitherto its life cycle in Britain has been regarded as incomplete because of the non‐viability of generation I (sexuales) on Sitka spruce and consequent absence of the subsequent generation II (fundatrix vera) and generation III (gallicolae). Both of these generations have been discovered for the first time in Britain and their development followed. The investigation began with the finding of the dead galls of A. cooleyi on Sitka spruce at Glen Tress in February 1935. Subsequently, dead galls were also found at Stobs, Melrose, Dreghorn and Murthly. At Melrose they were found on a new secondary host, the white spruce, Picea alba. Later the fundatrix vera of generation I was found. The growth of the galls was followed on cut twigs in the laboratory and on growing shoots in the field; galls of the current season were found at Glen Tress, Dreghorn and Murthly. The winged gallicolae of generation II were observed migrating to Douglas fir, where they settled and oviposited. From the eggs there hatched typical hibernating first‐instar nymphs (sistentes). Generation III (colonici) was determined to be triple‐brooded, and this character has recently been noted in Adelges cooleyi in British Columbia. The population of the sistentes on Douglas fir during any one winter was found to be composed of four categories, which hav* been designated. The migration of generation IV (sexuparae) to Sitka spruce and white spruce was observed at Glen Tress and Melrose respectively. It was also verified in the laboratory. Generation V (sexuales), for some cause or causes yet unknown, was practically exterminated during development. Only a few adults were observed. The solitary egg laid by the female of this generation was not discovered. Further investigation is required concerning: The causes of mortality of the sexuales. The oviposition of the sexual female, and the sexually produced egg. The extent of the distribution and establishment of the spruce generations in Britain. The prospective status of A. cooleyi as a pest of Sitka spruce in Britain. With regard to status, it would be unsafe, at the present juncture, to speculate, especially as the investigation has been conducted for only one year. I have, therefore, refrained from discussing possibilities of damage to the spruce host until more evidence is available.The writer is indebted to Mr R. Carrick, B.Sc, Research Student in the Department of Entomology, for the photograph of the winged gallicollae reproduced in PI. XXV, fig. 4. Part of the expenses incurred in conducting the investigation were met by a grant from the Earl of Moray Endowment of the University of Edinburgh, and it is a pleasure to acknowledge this assistance.

The Nesting Habits of the Little Carpenterbee, Ceratina Calcarata

The large carpenter-bee, Xylocopa virginica, is rightfully entitled to this name; the small carpenter-bee, Ceratina calcarata Robt., (Fig. 1), can furnish only part of the qualifications necessary to entitle her to the name. The former actually carves out with her powerful jaws new tunnels in the solid wood, grinding out sawdust as yellow and as real as any that comes from a steel blade. She seeks no soft or decayed portions, but cuts on into the sound wood with joyous vigor. The small carpenter-bee, so-called, burrows only into the soft pith of elder or sumac, and even then is able to use only the stems which have been cut or broken off, so as to afford her direct access to the soft pith within. If the soft portion is unexposed, Ceratina is unable to break through the ligneous wall and is obliged to seek another stem. Thus it is in only a very limited sense that this species may be called a carpenterbee. The similarity of common name of the two insects might lead one to expect similarity in looks, but in their physical appearance there is all the difference of David and Goliath, the one large and powerful in build, the other small and delicate. That they find the stems which have been cut was proven by a little experiment. In the middle of June, 1918, a large clump of sumac at Meramec Highlands gave no evidence of harboring any of these bees within their stems. I cut off the tops of about one-fourth of them (sixty-five in number) to make a place which would be attractive to home-seekers. When I returned a month later, seventy-five per cent, of the cut twigs were occupied by Ceratina calcarata, and not one of those uncut contained an occupant.