The effect of spruce cone insects on seed production in Switzerland

Abstract: In 1989 and 1990, spruce cones were harvested at 29 sites distributed over the five main geographic regions of Switzerland, i.e. Jura, Central Plateau, North, Central and South Alps. The presence of insects and the species-specific consumption of seeds was determined for each cone by examination of the median longitudinal section. Seven seed-feeding species ( Assara terebrella , Cydia strobilella , Dioryctria abietella , Eupithecia abietaria , Megastigmus strobilobius , Plemeliella abietina , Strobilomyia anthracina ) and the spruce cone gall midge Kaltenbachiola strobi were found in the samples. The proportions of infested cones ranged from 36 to 100%. The regions did not show significant differences in terms of infestation rates, whereas differences between sites within the regions were highly significant. Seed loss ranged from 2 to 100%, its geographical distribution exhibiting a similar pattern to the infestation rates. Considering the number of infested cones, C. strobilella was the most abundant species, followed by K. strobi and P. abietina . Cones infested by conospermatophagous species ( C. strobilella , D. abietella , E. abietaria ) showed higher seed losses than those infested by spermatophages ( M. strobilobius , P. abietina ). Due to the ubiquitous occurrence of C. strobilella , its high infestation rates and the resulting seed losses caused by its offspring, this species has to be considered as the most important insect seed predator in Switzerland. A multiple linear regression analysis was carried out for each region to simultaneously explore the impact of site and tree variables as well as the effect of insect attack on the yield of viable seeds. The results indicate that site and tree conditions contributed more to the variability of seed yield than insect presence in a cone. The model predicted significant effects of insect attack mainly for cones with total seed numbers that were higher than the average.     

The role of microtubule dynamics in growth cone motility and axonal growth

The growth cone contains dynamic and relatively stable microtubule populations, whose function in motility and axonal growth is uncharacterized. We have used vinblastine at low doses to inhibit microtubule dynamics without appreciable depolymerization to probe the role of these dynamics in growth cone behavior. At doses of vinblastine that interfere only with dynamics, the forward and persistent movement of the growth cone is inhibited and the growth cone wanders without appreciable forward translocation; it quickly resumes forward growth after the vinblastine is washed out. Direct visualization of fluorescently tagged microtubules in these neurons shows that in the absence of dynamic microtubules, the remaining mass of polymer does not invade the peripheral lamella and does not undergo the usual cycle of bundling and splaying and the growth cone stops forward movement. These experiments argue for a role for dynamic microtubules in allowing microtubule rearrangements in the growth cone. These rearrangements seem to be necessary for microtubule bundling, the subsequent coalescence of the cortex around the bundle to form new axon, and forward translocation of the growth cone.     

Host acceptance behavior of the red pine cone beetle (Conophthorus resinosae)

Adult female red pine cone beetles (Conophthorus resinosae Hopkins) (Coleoptera:Scolytidae) left cones of white pine (Pinus strobus L.) more readily than cones of red pine (Pinus resinosa Ait.) in the first 3 min after being placed on cones. Slices of white pine cones, however, did not elicit different beetle behavior than slices of red pine cones. Beetles bored into white pine as readily as into red pine. We conclude that beetles initially reject white pine due to structural traits, but eventually accept it during prolonged exposure and may utilize white pine in nature.

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Résumé C. resinosae Hopkins (Coleoptera, Scolytidae) s'alimente et pond sur les cônes de Pinus resinosa Ait.; il détruit souvent plus de la moitié des graines du pin dans la région des grands lacs aux USA. Cette espèce et les autres Conophthorus sont considérés comme des spécialistes très spécifiques. Nous avons voulu vérifier que les femelles de C. resinosae acceptent plus facilement comme hôtes les cônes de P. resinosae que ceux de P. strobus L. Au laboratoire, les scolytes ont abandonné les cônes de P. strobus plus rapidement que ceux de P. resinosae, au cours des 3 minutes qui ont suivi leur dépôt sur les cônes. Cependant des rondelles de P. resinosae n'ont pas été plus stimulantes que celles de P. strobus; les scolytes n'ont pas foré plus rapidement, ni n'ont plus séjourné sur P. resinosae que sur P. strobus au cours de 1, 2 ou 24 heures de l'expérience. Nous en concluons que les scolytes rejettent de prime abord P. strobus pour ses caractères structuraux, mais qu'ils l'acceptent éventuellement pendant expositions prolongées et peuvent le consommer dans la nature.

     

Host acceptance behaviour of the jack pine tip beetle, Conophthorus anksianae and the red pine cone beetle, C. resinosae

The jack pine tip beetle, Conophthorus banksianae McPherson (Coleoptera: Scolytidae) and the red pine cone beetle, C. resinosae Hopkins, are doubtful sibling species. However, it is possible that these two taxa are valid species that maintain reproductive isolation because they accept different hosts. In a series of laboratory and field cage experiments, the host acceptance behaviours of these two species under choice and no choice conditions were compared. The field experiments demonstrated that the two species have a similar propensity to accept jack pine cones and shoots for feeding, but differ consistently in their acceptance of red pine cones, and variably in their acceptance of red pine shoots. However, the laboratory experiments did not indicate a difference between the two species in their propensity to accept red pine cones for feeding. In field cages, C. resinosae accepted significantly more red pine cones for oviposition than C. banksianae; the situation was reversed for jack pine shoots. In comparison to C. banksianae, C. resinosae is a more generalist feeder. The results from this study suggest that host acceptance behaviour is a permeable barrier unable to ensure reproductive isolation between the two species. Although there are differences in the host acceptance behaviours between C. banksianae and C. resinosae, we conclude that these differences do not necessarily support their designation as distinct species.     

The role of the pyrogenic factor in the productivity and dynamics of the pine forests in Transbaikalia

Peculiarities of the dynamics and productivity of the pine forests growing under the conditions of the Transbaikalia arid climate are considered. Their high inflammability is noted. Fires sharpen the limiting role of moisture in tree growth. The post-fire annual ring fluctuations on longitudinal sections of young pines are illustrated. Outward diagnostic signs characterizing the xylogenesis state in trees damaged by fire have been analyzed: the char height on trunks, thermal damage to crowns, reduction and change in the tint of needle coloring. The process of digression dynamics of pyrogenic tree stands has been traced. Their reparation potential has been found to become weaker with ageing. As a result of the permanent effect of the pyrogenic factor, the productivity of pine forests in Transbaikalia is 1.5–2 times lower than of those in Priangarie.     

The role of birds and mammals in Korean pine (Pinus koraiensis) regeneration dynamics

This study examined the interrelationships of the fall seed-foraging guild with Korean pine (Pinus koraiensis) and its regeneration. The study took place in old-growth and secondary-growth forests in Northeastern China. Foraging behavior, seed transportation distance, and cache location of various birds and mammals were observed. Regeneration characteristics of Korean pine were also analyzed using plots in various vegetation cover types, successional stages, and topographical situations. Ten species of vertebrates were able to harvest seed from the closed-cone Korean pine. Of these, the Eurasian nutcracker, Eurasian nuthatch, red squirrel, and Siberian chipmunk were found to be potential seed dispersal agents. The nutcracker was the most important dispersal agent, easily acquiring seed with its large pointed bill, carrying up to 62 seeds in one trip, carrying seed at least 4 km, and placing seed in a variety of sites 2.5–3 cm deep in the soil. The Eurasian nuthatch carried a single seed per trip at distances less than 50 m, needed nutcrackers to open the cones and expose seed before they could acquire seed, and occasionally cached seed in the soil. Red squirrels were uncommon visitors to the tree tops of Korean pine, carried cones shorter distances than nutcrackers, and were only found under forest canopies. Human harvest of cones by knocking off branches also affected squirrel behavior and reduced future cone crops. Siberian chipmunks also collected seed from cones in trees and appeared to transport seed less than 50 m. Six other species were observed in this study successfully harvesting seed from cones but were not potential seed dispersers. Natural seedling establishment was found to be over 1000 seedlings/ha except on old-growth pine-hardwood sites. Squirrels were commonest here, but few seedlings survived past the 2nd year due to the intense shading. Second-growth forest types, including aPicea plantation where nutcrackers cached seed daily, and an old-growth pine-hardwood selective-harvest site, had the greatest regeneration. In conclusion, most natural regeneration of Korean pine in this part of its range is due primarily to the Eurasian nutcracker. Nutcrackers can aid forest managers in reaching desired stocking levels after disturbance, as well as a more natural-appearing forest. Squirrels, chipmunks, and nuthatches are minor seedling establishment agents. Korean pine seed is an important food source used by at least 22 species of forest wildlife.     

Identification of the cytokinins in red pine seedlings

Zeatin-9-riboside was identified in shoots and roots of Pinus resinosa by GC-MS analysis of its permethyl derivative. Based on their chromatographic properties on Sephadex LH-20 and C₁₈ HPLC, and their susceptibility to enzymatic degradation, several other cytokinins have been tentatively identified. The basic fraction of both the roots and shoots contained zeatin, whereas the shoots contained dihydrozeatin-O-glucoside and the roots contained zeatin-O-glucoside. Zeatin-9-riboside monophosphate, isopentenyladenosine monophosphate ([9R-5P]iP) and glucosyl phosphate derivatives were detected in the acidic fractions from both roots and shoots. There were equivalent amounts of [9R-5P]iP in both roots and shoots. The presence of equivalent amounts of [9R-5P]iP in both the roots and shots suggests that cytokinin biosynthesis may be occurring in both locations.Abbreviations AMP adenosine-5-monophosphate - BAP benzylaminopurine - BSA bovine serum albumin - BuOH butan-1-ol - CK cytokinin - (diH)Z dihydrozeatin - (diH OG)Z dihydrozeatin-O-glucoside - (diH OG)[9R]Z dihydrozeatin-9-riboside-O-glucoside - DW dry weight - EtOH ethanol - FW fresh weight - GC-MS gas chromatography-mass spectrometry - HPLC high-performance liquid chromatography - [9R]iP isopentenyladenosine - [9R-5P]iP isopentenyladenosine monophosphate - MeOH methanol - PVP polyvinylpyrrolidone - RFE rotary film evaporation - TEAB triethyl ammonium bicarbonate - Z zeatin - [9R]Z zeatin-9-riboside - (OG)Z zeatin-O-glucoside - [7G]Z zeatin-7-glucoside - [9R-5P]Z zeatin-9-riboside monophosphate     

Allelopathy of red pine: isolation and identification of an allelopathic substance in red pine needles

Since red pine (Pinus densiflora Sieb. et Zucc.) often forms sparse forest floors where herbaceous plants do not grow well, allelopathy of red pine was investigated. A growth inhibitory substance was isolated from an aqueous methanol extract of red pine needles and determined by spectral data as abscisic acid-β-d-glucopyranosyl ester (ABA-GE). This substance inhibited root and shoot growth of cress and E. crus-galli seedlings at concentrations greater than 0.1 μM. The concentrations required for 50% growth inhibition on roots and shoots of cress were 0.23 and 0.61 μM, respectively, and those of E. crus-galli were 1.1 and 2.8 μM, respectively. The activity of ABA-β-d-glucosidase, which liberates free ABA from ABA-GE, in cress and E. crus-galli seedlings was 13–29 nmol mg⁻¹ protein min⁻¹. Endogenous concentration of ABA-GE in the pine needles was 4.1–21.5 μmol kg⁻¹ and the concentration in soil water of the pine forest was 2.5 μM. The effectiveness of ABA-GE on growth inhibition and the occurrence of ABA-GE in pine needles and soil water suggest ABA-GE may play an important role in the allelopathy of red pine resulting in the formation of sparse forest floors.     

Developmental dynamics of cone photoreceptors in the eel

Background  

Many fish alter their expressed visual pigments during development. The number of retinal opsins expressed and their type is normally related to the environment in which they live. Eels are known to change the expression of their rod opsins as they mature, but might they also change the expression of their cone opsins?     

Long-term soil nutrient dynamics and lateral nutrient movement in fertilized and unfertilized red pine plantations

In this study, we use arepeated-measures analysis to test thehypothesis that soil fertility underpotassium-limited red pine (Pinusresinosa Ait.) stands at the Charles LathropPack Demonstration Forest in Warrensburg, NewYork is increasing toward a steady state thatwas artificially induced in fertilized standsby K-fertilization over 50 years ago. Wemeasured soil K by horizon and added new datato a 53-year database. We examine onemechanism that explains the higher rate of Kaccumulation in unfertilized stands comparedwith fertilized – lateral movement offertilizer K from treated plots to untreated –using the rubidium/potassium reverse tracermethod. Over the past five decades, soil Kconcentrations under both fertilized andunfertilized red pine have increasedsignificantly. The trends under fertilized andunfertilized plots demonstrate the gradualconvergence of soil K under unfertilized plotstoward concentrations in fertilized plots. Five decades after fertilization, treated soilsstill contain greater concentrations ofexchangeable K and lower bulk densities thanunfertilized plots. Analysis of Rb/K ratios inthe forest floor of fertilized and unfertilizedplots confirms the hypothesis that lateraltransport of surface broadcast fertilizer,applied over 50 years ago, extendsapproximately 11–16 m from the edges offertilized plots. The four unfertilized plotsclosest to fertilized plots have beensignificantly affected by inputs of fertilizerK, while the remaining five plots arerelatively unimpacted. Approximately 36% ofthe K in fertilized plots, and 23% of the K inunfertilized plots affected by fertilizermigration were derived directly from thefertilizer applied 5 decades ago, demonstratingthe highly conservative nature of mineralnutrient cycling in aggrading forests.     

A role for habitat area in the geographic mosaic of coevolution between red crossbills and lodgepole pine

Understanding how resource abundance limits adaptive evolution and influences species interactions is an important step towards developing insight into the role of microevolutionary processes in establishing macroevolutionary patterns. We examined how variation in resource abundance (forest area of lodgepole pine Pinus contorta ssp. latifolia) influenced patterns of co-adaptation and coevolution between red crossbill (Loxia curvirostra complex) and lodgepole pine populations. First, we found that crossbill abundance increased logarithmically as forest area increased in mountain ranges lacking a preemptive competitor (pine squirrels Tamiasciurus hudsonicus). Second, seed defences against predation by crossbills increased with increases in crossbill density, suggesting that seed defences have likely evolved in proportion to the intensity of selection that crossbills exert. Third, the average bill size of crossbill populations increased with increasing seed defences, which implies that crossbill offenses increased with increases in seed defences. The large bill size on the largest range is the result of coevolution with lodgepole pine with this crossbill population perhaps speciating. Local adaptation of crossbill populations on smaller ranges, however, is more likely the result of resident crossbills representing a subset of the potential colonists (phenotypic sorting) than of local evolution. In the smallest range, migration and possibly more frequent extinction likely impede local adaptation and may result in maladaptation.     

The evolutionary role and fate of the primary ovipositor in insects

The development of a piercing-sawing ovipositor for introducing eggs into living plant tissues has made its owners independent of the soil characteristics and increased egg protection. This was the most important prerequisite for the appearance of wings and flight which provided the winged insects with tremendous opportunities for finding new niches and led to unparalleled adaptive radiation. The ovipositor has passed several stages of improvement and differentiation. The four principal types of the primary ovipositor are considered: those of Odonata, Diaphanopteroidea (only extinct forms), Cicadina (including Paraneoptera and Hymenoptera), and Orthoptera. A new hypothesis of the gonangulum homologies is put forward, interpreting it as half of sternite IX lateral of the midline plus the paratergite of the same segment. The constructions of the valvae and different homologies of the third valvae in Polyneoptera and Eumetabola are discussed. The primary ovipositor has been repeatedly (i.e., in many lineages) reduced in the evolution of Pterygota. The main circumstances of these reductions are: (1) subterranean (fossorial) life in narrow cavities; (2) aquatic life of the larvae, mostly linked with submerged oviposition; (3) development and perfection of flight to which the heavy and protruding ovipositor was a hindrance. All the holometabolous insects except Hymenoptera lack the primary ovipositor.     

Organ-specific-active allelopathic substance in red pine needles

An organ-specific-growth inhibitory substance was isolated from an aqueous methanol extract of red pine needles and determined by spectral data as 1-mono(16-hydroxyhexadecanoyl)glycerol. This substance inhibited root growth of cress (Lepidium sativum L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv) seedlings at concentrations greater than 0.01 and 0.03???M, respectively. The concentrations required for 50?% growth inhibition on roots of cress and barnyard grass were 0.16 and 3.4???M, respectively. However, the inhibitory activity of the substance on shoots of cress and barnyard grass was very weak. The endogenous concentration of 1-mono(16-hydroxyhexadecanoyl)glycerol in the pine needles was 4.6???mol?kg^?1. Two related compounds, 1-monohexadecanoylglycerol and 16-hydroxyhexadecanlic acid had no activity up to 1,000???M on cress roots and shoots. The effectiveness of 1-mono(16-hydroxyhexadecanoyl)glycerol on root growth inhibition and the occurrence of 1-mono(16-hydroxyhexadecanoyl)glycerol in pine needles suggest the substance may play an important role in the allelopathy of red pine. Root-specific-growth-inhibition by the substance may be one of the strategies for red pine to compete with neighboring plants for nutrients and space because root growth of competitive plants may be very important for their whole plant development.     

Spectral tuning of deep red cone pigments

Visual pigments are G-protein-coupled receptors that provide a critical interface between organisms and their external environment. Natural selection has generated vertebrate pigments that absorb light from the far-UV (360 nm) to the deep red (630 nm) while using a single chromophore, in either the A1 (11- cis-retinal) or A2 (11- cis-3,4-dehydroretinal) form. The fact that a single chromophore can be manipulated to have an absorption maximum across such an extended spectral region is remarkable. The mechanisms of wavelength regulation remain to be fully revealed, and one of the least well-understood mechanisms is that associated with the deep red pigments. We investigate theoretically the hypothesis that deep red cone pigments select a 6- s- trans conformation of the retinal chromophore ring geometry. This conformation is in contrast to the 6- s- cis ring geometry observed in rhodopsin and, through model chromophore studies, the vast majority of visual pigments. Nomographic spectral analysis of 294 A1 and A2 cone pigment literature absorption maxima indicates that the selection of a 6- s- trans geometry red shifts M/LWS A1 pigments by approximately 1500 cm (-1) ( approximately 50 nm) and A2 pigments by approximately 2700 cm (-1) ( approximately 100 nm). The homology models of seven cone pigments indicate that the deep red cone pigments select 6- s- trans chromophore conformations primarily via electrostatic steering. Our results reveal that the generation of a 6- s- trans conformation not only achieves a significant red shift but also provides enhanced stability of the chromophore within the deep red cone pigment binding sites.     

Time resources and population dynamics in insects

An account is given of the way the temperature-mediated processes of development and locomotor activity in insects interact with the availability of essential resources to reduce lifetime fecundity below the potential predicted from laboratory performance. Current work on the sheep blowfly, Lucilia cuprina, is used to illustrate the points made wherever possible. Brief reviews of the ecologically important relationships between rate of development and temperature and level of activity and temperature are presented. The ways in which such laboratory-derived relationships may be applied in the interpretation of field results are described and discussed. The notions of time as a resource and of protein-food, mates and oviposition sites as limiting resources are presented and these provide the basis of a time/resource/fecundity mechanism limiting reproductive performance during the life-time of a female insect. Field and laboratory data are used to show the potentiality of such a mechanism for reducing life-time fecundity in the sheep-blowfly.     

The scientific value of the largest remaining old-growth red pine forests in North America

Old growth red pine forests (Pinus resinosa) cover less than 1% of their original range in North America and are essential for maintaining biodiversity at stand and landscape scales. Despite this, the largest remaining old-growth red pine forest in the world, the Wolf Lake Forest Reserve, is currently threatened by mining claims in Northern Ontario and has been receiving considerable media and public attention in recent months. We provide a timely review of how large old growth red pine forests maintain biodiversity at several taxonomic levels (with a focus on trees and plants) through heterogeneous partitioning of limiting resources such as light and nitrogen, formation of complex habitats through increased accumulation of coarse woody debris, and the maintenance of natural disturbance-driven succession. These processes shape the overstory community, allowing for the regeneration of pines, coexistence of early-mid successional shade intolerant species and cross-ecotonal establishment of late successional tree species in response to regional warming over the past three decades. Using Wolf Lake as a case study, we review legislation and policy complexities around this issue and provide scientific arguments for the preservation of this forest. We invoke recent insights into the ecological role of refugia, the development of criteria for assessing endangered ecosystems, and the challenges of conservation in the face of climate change and disturbance regimes. These forests are ecologically important and provide a scientifically irreplaceable system for assessing baseline ecosystem function, processes and services. As the largest remaining old-growth red pine forest in the world, Wolf Lake Forest Reserve deserves intensive study, monitoring and full protection from future development.