Epinotia Tedella Research Articles

Local outbreak of the spruce needle tortricid Epinotia tedella Clerk (Lepidoptera, Tortricidae) in the Sudetes in Poland

In 2004–2006 a local outbreak of Epinotia tedella was recorded on an area of 1,371 ha in Middle and Eastern Sudetes (Sowie and Bialskie Mts.) in Poland. In Bialskie Mts. slight damage dominated, while in Sowie Mts. more concentrated but moderate damage prevailed. The damage on older trees was limited to the lower half of the crowns, while on younger trees the middle parts of the crowns were more affected. The results of one-year field experiments towards the development of monitoring and forecast tools are presented in the paper. The results from ground emergence traps reflected phenology of butterflies’ emergence and the species preferences regarding older stands. The pheromone traps demonstrated the insect concentration on higher (above 900 m a.s.l.) elevations and confirmed the preference of older stands. Field observations revealed that a part of caterpillars can overwinter in the feeding places in tree crowns. The outbreak was incidental, with no effect on trees and stands. No new damage was recorded after 2006. The use of emergence traps and pheromone traps can be an interesting perspective, but further experiments concerning the interpretation of results are needed.

Detecting the causes of population cycles by analysis of R‐functions: the spruce needle‐miner, Epinotia tedella, and its parasitoids in Danish spruce plantations

Explaining the causes of regular multi annual oscillations (cycles) in animal populations has been a major problem for ecology, partly due to a lack of methodological rigor. In this paper we show how the analysis of R‐functions, the functional relationship between the per capita rate of change of a species and components of its environment, can be used to detect the causes of population cycles. Analysis of the R‐functions enables one to separate cycles due to negative feedback between species (endogenous causes) from those forced by one‐way effects (exogenous causes). We illustrate the approach by reference to the spruce needle‐miner inhabiting Danish spruce plantations, and conclude that population cycles in this insect are probably caused by interactions with two species of parasitic hymenoptera.

Volatiles of bracket fungi Fomitopsis pinicola and Fomes fomentarius and their functions as insect attractants

Volatiles released from fruiting bodies of the polypores Fomitopsis pinicola and Fomes fomentarius (Polyporaceae) were collected by entrainment and SPME techniques and analyzed by GC-MS. The most significant difference between the two species was found in the terpene fraction. F. fomentarius emitted a more complex blend, with more than 10 sesquiterpenes. During the sporulating phase, the release of (R)- and (S)-oct-1-en-3-ol, octan-3-one, and some sesquiterpene hydrocarbons (mainly β-barbatene) increased in F. pinicola, whereas in F. fomentarius the release of octan-3-one, cis-furanoid linalool oxide, β-phellandrene, β-myrcene, and several sesquiterpene hydrocarbons increased. β-Barbatene was identified for the first time in fungi. Chopping of the fruiting bodies altered the odor composition more in F. fomentarius than in F. pinicola. Five volatiles giving a typical fungal odor (rac-oct-1-en-3-ol, nonan-1-ol, rac-octan-3-ol, octan-1-ol, and octan-3-one) were tested for insect attraction in the field. Females of the three wood-living generalist beetles Malthodes fuscus, Anaspis marginicollis, and A. rufilabris and both sexes of the moth Epinotia tedella were attracted to rac-oct-1-en-3-ol. The generalist predator on fungus-insects Lordithon lunulatus was attracted to rac-oct-1-en-3-ol and octan-3-one in combination. Previous results regarding the host-specific attraction of beetles to the odors emanating from chopped fruiting bodies of F. pinicola and F. fomentarius are discussed in the light of this investigation.

DETECTION OF DELAYED DENSITY DEPENDENCE: REPLY

Hansson, L., and H. Hentonen. 1985. Gradients in density variation of small rodents: the importance of latitude and snow cover. Oecologia 67:394-402. Haukioja, E., S. Neuvonen, S. Hanhimaki, and P. Niemeli. 1988. The autumnal moth in Fennoscandia. Pages 163-178 in A. A. Berryman, editor. Dynamics of forest insect populations: patterns, causes, implications. Plenum, New York, New York, USA. Holling, C. S. 1965. The functional response of predators to prey density and its role in mimicry and population regulation. Memoirs of the Entomological Society of Canada 45:5-60. Mason, R. R., and B. E. Wickman. 1988. The Douglas-fir tussock moth in the interior Pacific Northwest. Pages 179209 in A. A. Berryman, editor. Dynamics of forest insect populations: patterns, causes, implications. Plenum, New York, New York, USA. Montgomery, M. E., and W. E. Wallner. 1988. The gypsy moth: a westward migrant. Pages 353-375 in A. A. Berryman, editor. Dynamics of forest insect populations: patterns, causes, implications. Plenum, New York, New York, USA. Morris, R. F 1959. Single factor analysis in population dynamics. Ecology 40:580-588. Munster-Swendsen, M. 1985. A simulation study of primary-, cleptoand hyperparasitism in Epinotia tedella (Lepidoptera, Tortricidae). Journal of Animal Ecology 54: 683-695. Royama, T. 1977. Population persistence and density dependence. Ecological Monographs 47:1-35. . 1981. Fundamental concepts and methodology for the analysis of animal population dynamics, with particular reference to univoltine insects. Ecological Monographs 51: 473-493. . 1992. Analytical population dynamics. Chapman & Hall, Oxford, England. Turchin, P. 1990. Rarity of density dependence or population regulation with lags? Nature 344:660-663. . 1991. Nonlinear modeling of time series data: limit cycles and chaos in forest insects, voles, and epidemics. Pages 39-62 in J. A. Logan and F P. Hain, editors. Chaos and insect ecology. Virginia Experiment Station Information Series 91-3. Virginia Experiment Station, Blacksburg, Virginia, USA. . 1993. Chaos and stability in rodent population dynamics: evidence from nonlinear time series analysis. Oikos 68:167-172. Turchin, P., and A. D. Taylor. 1992. Complex dynamics in ecological time series. Ecology 73:289-305. Williams, D. W., and A. M. Liebhold. 1995. Detection of delayed density dependence: effects of autocorrelation in an exogenous factor. Ecology 76:1005-1008.

Levels of damage of Scots pine and Norway spruce caused by needle miners along a SO2 gradient

Needle damages caused by mining insects on Scots pine and Norway spruce were studied in the vicinity or a pulp mill. The abundance of needles mined by the pine bud moth Exoteleia dodecella (Lepidoptera: Gelechiidae) on Scots pine Pinus sylvestris, and the spruce needle miner Epinotia tedella (Lepidoptera: Tortricidae) on Norway spruce Picea abies had a significantly peaked response curve on logarithmic distance scale. For pine bud moth, the maximum expected population density was estimated to be at the distance of 1.35 km from the factory. The maximum expected population density for the spruce needle miner was at the distance of 1.53 km from the factory. However, for both species the curves were significantly different among transects. Both species had a peaked and significant response to sulphur level in needles as well. The maximum expected density in pine was at 1270 ppm, and in spruce at 1070 ppm sulphur concentration in pine needles. The results are consistent with earlier reports demonstrating that these mining insects frequently attack trees suffering from air pollution. The nonlinear response of both species to distance from the pulp mill suggests that E. dodecella on pine and E. tedella on spruce are rather indicators of the zone of intermediate air pollution than of strongly polluted or nearly unpolluted sites. This also agrees with the plant stress‐insect performance hypothesis indicating that insect response varies with the magnitude of stress, and at very high stress levels a tree no longer provides the insects with relevant food.

A Simulation Study of Primary-, Clepto- and Hyperparasitism in Epinotia tedella (Lepidoptera, Tortricidae)

SUMMARY (1) A model of combined parasitism in the spruce needleminer, Epinotia tedella (Cl.) is proposed. It covers the effect of two primary parasitoids, Pimplopterus dubius (Hgn.) and Apanteles tedellae Nix., a cleptoparasitoid, Campoplex cursitans (Hgn.), and a hyperparasitoid, Mesochorus silvarum Curt. The analysis of field data makes use of the log killing power/log parasitoid density relationship, and thereby, indirectly, the pseudo-interference submodel of parasitism. (2) The impact of individual species is analysed by means of computer simulations. The

New sex attractants for 35 tortricid and 4 other lepidopterous species, found by systematic field screening in The Netherlands

Most of the known sex attractants and pheromones found for Tortricidae attract species of the subfamily Tortricinae. In order to find more sex attractants for species of the subfamily Olethreutinae, about 60 one- and two-component lures were screened for attractancy in different biotopes in the Netherlands. Most of the chemicals tested were straight-chain dodecen-1-ols and their acetates. The species captured belonged to the following families and subfamilies: Tortricinae (5), Olethreutinae (30), Noctuidae (2), Gelechiidae (1), Gracillariidae (1). Some of the species captured are recorded as pest species in forestry:Epinotia tedella, Gypsonoma aceriana, Cydia strobilella, C. zebeana, Petrova resinella, Blastesthia turionella, andB. posticana.

New sex attractants for 35 tortricid and 4 other lepidopterous species, found by systematic field screening in the Netherlands

Most of the known sex attractants and pheromones found for Tortricidae attract species of the subfamily Tortricinae. In order to find more sex attractants for species of the subfamily Olethreutinae, about 60 one- and two-component lures were screened for attractancy in different biotopes in the Netherlands. Most of the chemicals tested were straight-chain dodecen-1-ols and their acetates. The species captured belonged to the following families and subfamilies: Tortricinae (5), Olethreutinae (30), Noctuidae (2), Gelechiidae (1), Gracillariidae (1). Some of the species captured are recorded as pest species in forestry:Epinotia tedella, Gypsonoma aceriana, Cydia strobilella, C. zebeana, Petrova resinella, Blastesthia turionella, andB. posticana.

Interactions Within a One-Host-Two-Parasitoids System, Studied by Simulations of Spatial Patterning

(1) A model of parasitism and spatial distribution was constructed using field observations of a natural system: The tortricid Epinotia tedella (Cl.) and its two primary parasitoids, Pimplopterus dubius (Hgn.) and Apanteles tedellae Nix. The latter species is the inevitable winner in cases of multiparasitism, and neither of the parasitoids shows any discrimination ability. Local search is random, but at a larger scale the attacks of A. tedellae are aggregated. (2) As the distribution of hosts and parasitoid attacks is apparently governed by the preference of the species for certain physical conditions, the distributions were modelled as fixed patterns. Apanteles tedellae showed a stable interaction with the host, due to its aggregation, whereas P. dubius provoked increasing host fluctuations, even when all three species were acting together. (3) Both parasitoids could eliminate each other, depending on their searching constants, and change the system into a stable or unstable two-species system. A stable coexistence of the three species proved not to be attainable. (4) Various distribution patterns of P. dubius were simulated, and it was found that distinct aggregation of this species led to its elimination by A. tedellae-except when P. dubius was much more strongly aggregated, and provided with a much higher searching constant, than its competitor. (5) Aggregation pattern, in combination with the searching ability, strongly affected competition between the parasitoids. The multiparasitic loser was eliminated from aggregations at high host densities because of multiparasitic overlap. However, aggregation in patches of low host density, with low host exploitation, also resulted in competitive exclusion. Thus, the lack of distinct aggregation proved to be beneficial for the multiparasitic loser, P. dubius. (6) As expected, simulated dispersal of P. dubius resulted in coexistence, but the dispersal influenced the apparent log a/log P relation (pseudo-interference) by turning the, otherwise curvilinear, relationship into an almost linear function. Thus, the 'pseudointerference'-model of parasitism may include dispersal as well as spatial and temporal distributions.

The distribution in time and space of parasitism in Epinotia tedella (CI.) (Lepidoptera: Tortricidae)

Abstract. The temporal and spatial distribution of parasitism in Epinotia tedella was investigated within two spruce stands. Most eggs were laid by the host female early in the season. The parasitoid, Pimplopterus dubius, was subjected to a temporal stress, and it also exhibited a greater oviposition rate early in its life. The temporal distribution of attack frequencies by P.dubius and Apanteles tedellae showed a good adaptation to the phenology of the host. The spatial distribution of flight activity indicated a preference to exposed sub‐habitats by P.dubius and to dark and sheltered sub‐habitats by A.tedellae. The distribution of host larvae showed an aggregation in the lower and central parts of the canopy, and so did the attacks by A.tedellae— even more pronounced. The attacks by P.dubius showed a slightly inverse aggregation pattern. Apparently, the distribution of attacks was caused by preference to physical conditions, rather than local host densities. The decreasing log. area of discovery on increasing log. parasitoid density is obviously a ‘pseudo‐interference’ phenomenon caused by the aggregation of A.tedellae, and temporal asynchrony in P.dubius. P.dubius dominated in young stands and its importance decreased with increasing age of the stands. The importance of A.tedellae was greatest in stands between 20 and 40 years old, and it dominated in those stands that were especially dense and dark, due to absent thinnings.

Asynchrony in Insect Host-Parasite Interaction and its Effect on Stability, Studied by a Simulation Model

SUMMARY (1) The model is based on a natural host-parasite system, the tortricid Epinotia tedella Cl. and its dominant parasite Pimplopterus dubius Hlmg. It is shown how field data on hatching, emergence and activity are used in the description of the frequency of susceptible hosts and searching parasites throughout the generations. Random search by the parasites has been adopted for the daily events, but not for the generation as a whole. (2) Moderate asynchrony, expressed as relative displacement of the temporal frequency curves for host and parasite, leads to stability, whereas the model predicts instability when the populations are synchronized and when asynchrony becomes extreme. (3) Asynchrony leads to curvilinear relationships between the calculated log (apparent area of discovery) and log (parasite density) without assuming mutual interference between parasites. It is suggested that a majority of the observed log a/log P relationships described in the literature are results of asynchrony, spatial incoincidence and aggregative behaviour, and not of any significant mutual interference. (4) To keep the model realistic, also under extreme conditions, a maximum oviposition rate of eight eggs per day per female parasite was adopted. However, the effect of asynchrony on stability did not change when this assumption was cancelled. (5) The initial densities of host and parasite proved to be of importance only in the vicinity of the limits between regions of stability and instability. (6) It is suggested that the present system, as well as other host-parasite systems, may well be described by a simple, predictive and non-explanatory model either through an apparent log a/log P relation or through an exploitation submodel using a negative binomial distribution.

Parasitär bedingte Wachstumshemmung bei den Larven von Epinotia (= Epiblema) tedella Cl. (Lep., Tortricidae)1

AbstractParasitically induced growth inhibition in Epinotia (= Epiblema) tedella Cl. larvae. The endoparasitic larva of Apanteles tedellae Nix. inhibits the larval growth of its host, Epinotia tedella, much more than the Lissonota dubia Hgn. larva does, although the life habits of both parasite species are very similar. Presumably the strong effect of Apanteles comes from a general change in the host's metabolic system, the slight inhibition by Lissonota, however, from the increasing food consumption of the growing parasite larva.