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Problems of influencing insect populations by changing the food quality. In forest entomology, as opposed to plant and livestock breeding it is not possible at the present stage to make use of changes in food quality as a routine technique for influencing insect populations. Although noticeable reactions of insects to changes in food quality have been known for a long time research on this matter has not yet reached a stage far beyond a first tentative screening. A careful elaboration of these questions is suggested to master the forthcoming problems like the cultures of clones of spruce trees or fertilizing of forest trees.

Destructive outbreaks of forest pests are classified as gradient, cyclical or eruptive. The first of two types of outbreaks (gradient, cyclical) are generated by stand and site conditions conducive to the reproduction and survival of the pest or stressfull for the host plant(s). In these cases, outbreak probability, or risk, can be assessed with unidimensional risk equations. Outbreaks of the third type, the eruptive pests, are more difficult to predict because the density of the pest plays a critical role in initiating outbreaks in particular stands. Risk assessment models for these pests require a two-dimensional structure that integrates stand, site and insect numbers. We discuss methods for developing risk assessment models for eruptive pests using, as an example, mountain pine beetle populations infesting lodgepole pine stands. Zusammenfassung Beurteilung des Risikos bei Forstinsekten-Kalamitaten Schadliche Massenvermehrungen von Forstinsekten werden eingeteilt in gradierende, zyklische und eruptive. Die ersten beiden Typen werden durch Bestandes- oder Lagebedingungen hervorgerufen, die fur die Reproduktion und das Uberleben des Schadlings gunstig oder fur die Wirtspflanze ungunstig sind. In solchen Fallen kann die Kalamitatswahrscheinlichkeit bzw. das Risiko mit eindimensionalen Gleichungen beurteilt werden. Kalamitaten des eruptiven Typs sind schwieriger zu prognostizieren, weil die Schadlingsdichte eine ausschlaggebende Rolle bei der Auslosung der Vermehrung in einzelnen Bestanden spielt. Modelle zur Risiko-Beurteilung erfordern hier eine zweidimensionale Struktur, in welcher Bestand, Lage und Insektendichte integriert sind. Es werden am Beispiel eines Befalls von Lodgepole-Kiefern durch den Mountain Pine Beetle Erorterungen uber die Entwicklung von Risikobeurteilungs-Modellen fur eruptive Schudlinge angestellt.

Changes in structure or community composition within forest ecosystems and their patterns in time and space affect insect populations. Silvicultural measures may cause temporary disturbances or have long-term influences on the ecosystems. They may determine insect distribution and general levels of abundance or they may change the manner in which populations fluctuate. The management of limiting resources for bark beetles such as Tomicus piniperda, Ips typographus, and Pityogenes chalcographus is discussed and exemplified by a simple population model. The combined effects of cutting and other silvicultural measures on pine weevil (Hylobius abietis) populations and damage are reviewed. The influences of stand structure and size on forest insect populations are discussed using Aradus cinnamomeus and pine shoot moths as examples. Zusammenfassung Waldbau und Insektenprobleme Anderungen in forstlichen Okosystemen und in den zeitlichen und raumlichen Verhaltnissen der Lebensgemeinschaften beeinflussen Insektenpopulationen. Waldbauliche Masnahmen konnen als Storungen oder als determinierende Faktoren in den Okosystemen wirken. Sie konnen die Verbreitung und die durchschnittliche Haufigkeit einer Insektenart bestimmen oder die Charakteristik der Fluktuationen einer Population andern. Die Bedeutung und waldbauliche Behandlung populationsbegrenzender Requisiten wird an den Beispielen der Borkenkafer Tomicus piniperda, Ips typographus und Pityogenes chalcographus erlautert und durch ein einfaches Populationsmodell illustriert. Die kombinierte Wirkung von Holzeinschlag und anderen waldbaulichen Masnahmen auf Vorkommen und schadlichen Fras des Russelkafers Hylobius abietis wird besprochen. Auch Masnahmen, die Grose und Struktur von Bestanden beeinflussen, wirken auf Insektenpopulationen ein, z. B. auf Kiefernrindenwanzen und Knospen- und Triebwickler an Kiefern.

Contributions to the knowledge of forest insect pests in Iran. II. Macrolepidoptera In 1972, part I: Coleoptera, has been published in this journal. Now the view of the insects, damaging trees in Iran, is continued with part II: Macrolepidoptera. At first a survey on landscape and forest vegetation in Iran is given, followed by a summary about the forest protection. Then 138 species of Macrolepidoptera, in alphabetical order, are enumerated. Informations on synonymy, distribution, bionomy and economic importance of the different species are given. Zusammenfassung 1972 wurde Teil I: Coleoptera in dieser Zeitschrift veroffentlicht. Die Liste der Insekten, die Schaden an Waldbaumen verursachen, wurde mit Teil II: Macrolepidoptera fortgefuhrt. Landschaft und Waldvegetation im Iran wurde kurz beschrieben und uber den Forstschutz berichtet. Anschliesend wurden 138 Arten von Macrolepidoptera in alphabetischer Reihenfolge behandelt und Auskunft uber Synonyma, Verbreitung, Bionomie und wirtschaftliche Bedeutung der verschiedenen Arten gegeben.

As to food quality of spruce needles for forest damaging insects. 15. Comparative studies on the development and the rates of intake of protein-amino acids of Gilpinia hercyniae-larvae feeding on the same branches of spruce under controlled and field conditions 13-, 19-, 22-, and 23 day old populations of the 100th generation of larvae of Gilpinia hercyniae which were reared under controlled conditions were divided into two groups. Each group was kept simultaneously on the same exactly defined branches of spruce under controlled and field conditions. Technical details of the caging under field conditions and of the analysis of amino acids with a large number of samples are described. The characteristics of the larval development (table 2) and of the rates of intake of protein-amino acids (fig. 3) were determined. Nine partial experiments showed that a very similar weight was reached by the larvae independent of the larval age at the beginning of the experiment and of the external conditions. Furthermore it was found that within every experiment the profiles of the graphically evaluated rates of intake for the individual amino acids as a funtion of time are similar for the partial populations kept under field- and laboratory conditions, respectively. Since the intervals of the sampling dates were chosen schematically (every 2nd day) and not proportionally to the time span of development the characteristic points of the profiles are compressed in the diagram of the laboratory data as compared to those of the field. Since genetically homogenous larval populations were used the similarity of the maximal weight gained and of the rates of intake of the protein amino acids in the simultaneous laboratory- and field experiments are considered to be due to the needle qualities. These are genetically fixed for the respective single trees, and their expression as related to the external conditions chosen in the experiments can be described by the rates of intake for the individual amino acids as a function of observation time. Zusammenfassung 13, 19, 22 und 23 Tage alte Larvenpopulationen der 100. Generation einer Laborzucht von Gilpinia hercyniae wurden zu jeweils gleichen Anteilen an demselben genau definierten Nadelmaterial von Fichte unter Labor- und Freilandbedingungen gehalten. Technische Einzelheiten der Zwingerung unter Freilandbedingungen und der Aminosaurenanalyse bei umfangreichem Probe-material werden beschrieben. Die Kenndaten der Larvenentwicklung (Tab. 2) und die Aufnahmeraten der Proteinaminosauren (Abb. 3) sind bestimmt worden. Es wird gefunden, das unabhangig vom Larvenalter und den Ausenbedingungen in allen neun Teilversuchen ein sehr ahnliches maximales Gewicht erreicht wurde und innerhalb der einzelnen Versuche zwischen den Varianten Freiland und Labor die Profile der graphisch ausgewerteten Aufnahmeraten fur die einzelnen Aminosauren als Funktion der Zeit ahnlich sind. Da die Intervalle der Probennahme schematisch (alle 2 Tage) und nicht proportional zur Entwicklungszeit gelegt wurden, erscheinen die Kennpunkte der Profile bei Laborhaltung gegenuber denen unter Freilandhaltung zeitlich gerafft. Auf Grund des Einsatzes von genetisch einheitlichem Tiermaterial wird die Ahnlichkeit des erreichten maximalen Gewichts wie der Aufnahmeraten der Proteinaminosauren im kombinierten Labor- und Freilandversuch auf Nadeleigenschaften zuruckgefuhrt, die fur die jeweiligen Einzelbaume genetisch festgelegt sind und deren Auspragung durch die Umweltbedingungen fur die im Versuch gegebenen Verhaltnisse mittels der Aufnahmeraten fur die einzelnen Aminosauren als Funktion der Beobachtungszeit beschreibbar ist.

Zusammenfassung Es werden eine Reihe von Beobachtungen uber Auftreten und Bedeutung einiger Forstschadlinge in der Turkei mitgeteilt. Die bisher unbekannte Lebensweise von Leptura ciliciensis Dan. wird beschrieben. Pseudopachymerina lallemantii Marseul vernichtete 90% Samen von Acacia odorata. Es wurde festgestellt, das Lithocolletis platani Stgr. als Raupe in den Minen der abgefallenen Platanenblatter uberwintert. Summary A series of observations has been made on the incidence and importance of some forest insect pests of Turkey. The life history of Leptura ciliciensis Dan. – hitherto unknown – is described. Pseudopachymerina lallemantii Marseul destroyed 90% of the seeds of Acacia odorata. It has been found that Lithocolletis platani Stgr. overwinters as a larva in the mines of leaves of Platanus fallen to the ground.

Principles involved in the orientation of bark beetles. The complete reproductive process of forest insect pests breeding (“gebunden lebenden”) in bark and phloem (e.g. bark beetles) can be divided into three phases: orientation, attack, and the breeding phase including the establishment of larval galleries. Successful orientation, i.e. the selection of suitable breeding material, is essential for the reproduction of these species. The orientation, which precedes attack on the breeding material, is based on the relations and reactions between the pest species and the tree. The principles involved in the orientation reactions of pests (e.g. changes in reaction phases, optimal level of stimuli, and the threshold principle) are described with examples. The orientation which precedes an attack does not always lead to successful development of a new generation (e.g. because of reactions of living breeding material). If, after successful orientation, a specimen of the population attacks the breeding material and by producing population pheromones attracts other specimens to the same material, this is to be considered part of the attack phase.

Summary Observations regarding outbreaks of Euproctis chrysorrhoea L. have been recorded in the Netherlands since 1940 by the Forest Insect Survey of the Itbon: 1. Usually, damage by the caterpillars only occurred in the southern and western parts of the country, but during very heavy outbreaks also further north. 2. The number of host species appeared to increase with the seriousness of the outbreak. 3. Apparently, in most cases, outbreaks resulted from the development of the endemic population. 4. The woody species were attacked in a definite order. 5. It is considered likely that this order is that in which the different species become suitable as food, as the result of different weather conditions.