Anderbrant, O. 1988. Survival of parent and brood adult bark beetles ips-typographus in relation to size lipid content and reemergence or emergence day. Physiol. Entomol. 13 (2). 121-130. ab This study investigated a possible trade-off between bark beetle reproductive effort and future survival. Parent adult Ips typographus (L.) (Coleoptera: Scolytidae) were collected when they re-emerged from a laboratory culture after completing their first brood and held at constant temperatures of 4 or C. As a comparison, emerging brood adults were collected and held at C. The longevity of the beetles was related to when they re-emerged or emerged (measured in days since parent introduction) and to their size (pronotal width), fresh weight and lipid content at collection, by multiple regression analysis. The expression (fresh weight .times. pronotal width-2.6), used as an estimate of lipid content of the living beetles, was significantly correlated (r = 0.67, P < 0.001) with the actual (extracted) lipid content. At C, fat content was the variable most strongly correlated with survival time in all beetle groups except parent females. In both parent and brood females, re-emergence or emergence day, respectively, contributed significantly to the explanation of survival time, whereas pronotal width and fresh weight never contributed significantly to the regression equation. At C, fat content was not estimated but, re-emergence day was negatively correlated with survival time. In conclusion, beetles with high fat content and re-emerging or emerging early have longer expected survival than beetles leaving the log later or containing less fat. This means that females laying a large first brood might suffer a somewhat higher mortality than females laying a smaller brood. LG EN.

Austara, O., Annila, E., Bejer, B., & Ehnstrom, B. 1984. Insect pests in forests of the nordic countries 1977-1981. Fauna. Norv. Ser. B. 31 (1). 8-15. ab During the present 5-yr period, the spruce bark beetle Ips typographus L. continued to be the most serious pest problem (on pine and spruce) in Norway and Sweden. In Finland, Norway and Sweden extensive outbreaks of the European pine sawfly Neodiprion sertifer Geoffroy occurred throughout the 5-yr period. Other important pests are discussed, and pests of minor importance are listed in tabular form. (including other Coleoptera, Hymenoptera, Lepidoptera, Diptera, Homoptera and Acarina). LG EN.

Bakke, A., & Strand, L. 1981. Pheromones and traps as part of an integrated control of the spruce bark beetle ips-typographus some results from a control program in norway in 1979 and 1980. Nisk. Nor. Inst. Skogforsk. Rapp. 0 (5). 5-39. ab Pheromone dispensers containing methylbutenol (1500 mg), (S)-cis-verbenol (70 mg) and ipsdienol (10 mg-15 mg) were used with drainpipe traps as part of a control program for the spruce bark beetle, I. typographus L. About 600,000 traps were deployed in south Norway in 1979 and 1980. Approximately 1% in 1979 and 1/2% in 1980 were selected as test traps. The main catches were made before the middle of June, 79% of season total catches in 1979 and 96% in 1980. The average catch per trap was 4701 beetles in 1979 and 7406 in 1980, but the variations in numbers were considerable, depending on trap location and the local size of beetle population. The highest average trap catch, 11,701 beetles, was recorded in Vestfold county in 1980. The damage within 100 m distance of traps was lower in 1980, compared with 1979. The degree of improvement was highest on sites with minor infestation in 1979. New infestation in 1980 was recorded at 30% sites with minor attack (1-5 trees) the year before, whereas 70% of sites with extensive infestation (> 30 trees) had new infestation. LG NO.

Botterweg, P.F. 1982. Dispersal and flight behavior of the spruce bark beetle ips-typographus in relation to sex size and fat content. Z. Angew. Entomol. 94 (5). 466-489. ab Experiments and observations were made to study the flight behavior and dispersal of I. typographus (a scolytid) at a diapause size, inside and between forest areas (Norway) with respect to sex, size and fat content. The beetles diapause in the soil 0-5 m from the tree in which they have matured. During diapause the beetles' fat content reduces to .apprx. 50%. When the beetles emerge at springtime, they may react directly to pheromones. In 1 day I. typographus beetles can disperse over long distances (up to 750 m), and a homogenous distribution of the beetles over the forest area is reached as long as no pheromone sources exist that aggregate the beetles. The beetles were able to disperse over long distances (> 8 km). The flight intensity of the beetles was positively correlated with temperature. At wind speeds over 1 m s-1 the beetles flew mostly with the wind, at lower wind speeds they tended to fly against the wind after contact with pheromones. The dispersal and flight behavior was not affected by the beetle's sex, size or fat content. The adult beetles that emerge from a tree to establish a 2nd brood were on average larger than beetles that remained in the tree; the males built up a new fat reserve before they emerged. The dispersal and flight behavior of the beetles reduces the effectiveness of mass trapping as a control strategy. Decreasing I. typographus population suffer a high mortality caused by predation and parasitism. LG EN.

Botterweg, P.F. 1983. The effect of attack density on size fat content and emergence of the spruce bark beetle ips-typographus. Z. Angew. Entomol. 96 (1). 47-55. ab A photometric method to measure the relative fat content of bark beetles and other small invertebrates is presented. The method is less labor intensive than extraction of the fat with petroleum ether. A relation is found between the weight of the elytra and the beetle's dry weight which permits comparison of the bettle's size by comparing the weight of their elytra. From the absolute fat content and the elytra weight, the relative fat content (mg fat/mg dry weight) can be calculated. The method described was used to measure the changes in size and fat content of the spruce bark beetle L. typographus L. and the effect of attack density on these characteristics. Nine logs in netting cages were attacked by I. typographus beetles at attack densities ranging from 0.15-2.59 entrance holes dm-2 bark. The emerging offspring were sampled twice a week, and their size and relative fat content measured. Twenty-seven percent of the offspring had emerged from the logs by Oct. 16th when emergence nearly stopped because of low temperatures. Males usually emerged before females. The size and fat content of the emerging beetles was positively correlated with the time of emergence. The size and fat content of the emerging beetles was negatively correlated with attack density. LG EN.

Byers, J.A. 1984. Electronic multiprobe thermometer and multiplexer for recording temperatures of microenvironments in the forest litter habitat of bark beetles coleoptera scolytidae. Environ. Entomol. 13 (3). 863-867. ab An electronic integrated-circuit thermometer with multiple probes (3 by 4 by 5 mm each) is described and was used to measure temperatures at the surface and at several depths in the forest litter of Norway spruce, Picea abies (L.) Karst., throughout 3 days in spring. The temperatures at the various depths were recorded on a single-pen recorder/voltmeter by means of a multiplexing circuit which in turn connected each of 4 or more sensor probes to the amplifying circuit and pen recorder for a specific amount of time. This scanning time per probe can be adjusted from 1 s to about 1 h. The possible effects of temperature in the forest litter on the survival and flight initiation of bark beetles, especially Ips typographus (L.), during their spring swarming is discussed. LG EN.

Byers, J.A. 1996. An encounter rate model of bark beetle populations searching at random for susceptible host trees. Ecological. Modelling. 91 (1-3). 57-66. Issn 0304-3800. ab Iterative equations were developed that predict the encounter rate between a population of moving animals and a population of stationary objects, where the animals cease to search upon finding an object. The encounter rate through time depends on the number of searching animals (bark beetles), number of stationary objects (host trees), average speed of the animals, average radius of the object, and area of the search arena. The iterative equations were used in a computer program to vary these parameters with regard to flight dispersal of the bark beetle Ips typographus (Coleoptera: Scolytidae) during their search for susceptible host trees of Norway spruce (Picea abies). Realistic parameters of flight speed, numbers of beetles and susceptible host trees, tree diameters, density of healthy trees. search area, and time searching were held constant while certain of these parameters were varied in computer model runs. In most cases, significant proportions of the modeled bark beetle population (of which individuals fly forward with a random component) found the relatively few susceptible host trees suitable for colonization. Only at very low effective flight speeds (due to longer stays on trees) or with widely distributed hosts of smaller diameter, did relatively few beetles find suitable hosts. Once the 'pioneer' beetles find susceptible hosts. release of aggregation pheromone would greatly increase the effective radius of the host and allow rapid concentration of the population on these trees. The model suggests that primary attraction to host tree volatiles is not mandatory for host finding and selection in many species of bark beetle. Evolution of an olfactory response to host volatiles is more probable in species with low population densities or widely dispersed host plants, or both. Also, there would be little selection pressure on a bark beetle species to evolve aggregation pheromones if they can respond over some meters to plant volatiles that reveal the location of a susceptible host. LG EN.

Byers, J.A., & Lofqvist, J. 1989. Flight initiation and survival in the bark beetle ips-typographus coleoptera scolytidae during the spring dispersal. Holarct. Ecol. 12 (4). 432-440. ab Temperatures in the forest litter of Norway spruce Picea abies were recorded throughout the day to obtain environmental parameters that could be used to design realistic flight-activity experiments in the laboratory. Flight activity and survival were monitored electronically in plastic chambers where the conditions were controlled by an environmental chamber. Flight attempts of the bark beetle Ips typographus were initially lower in chambers with forest duff but were prolonged compared with those of beetles in chambers with a metal screen substrate. Small bark slabs and spruce twigs in the duff were utilized as food and extended the period of flight and survival. A thermal gradient in duff from at the surface down to C at a depth of 4 cm also slightly increased the survival of beetles compared with a constant A daily ambient temperature cycle as well as the duff thermal gradient increased the survival from about 3 d to more than 8 d. The latter length in the laboratory agreed with survival rates of caged beetles in a clearcut forest area, while beetles caged in the forest survival for more than 14 d. Temperatures were monitored at the duff surface of the caged beetles and compared with the catches of beetles that were attracted to a pheromone trap and collected with an electronic fraction collector. Information on flight and survival during the dispersal period is necessary to the design of ecologically sound management programs for control of bark beetles. LG EN.

Duelli, P., Studer, M., & Naef, W. 1986. The flight of bark beetles outside of forest areas. J. Appl. Entomol. 102 (2). 139-148. ab Flight phenologies and vertical distribution of bark beetle flight were investigated in an agricultural area at least 420 m way from potential breeding places. Pheromone traps (Pheroprax, Linoprax) and unscented sticky traps (square grids of 1 m2) were fixed on a meterological mast at 9 different heights from 1.7 m up to 150 m. Of the 12 scolytid species recorded in 1984, Ips typographus L. (N = 287) and Pityogenes chalcographus L. (N = 319) were the two most abundant species. The vertical flight distribution of I. typographus shows a marked peak at 5 m. Less than 5% flew higher than 10 m, with 1 individual at 100 m. More females than males were caught in the pheromone traps. Maximum catches of P. chalcographus were at the lowest level, at 1.7 m. Decrease in numbers with height is slower than in I. typographus; 14% flew higher than 10 m. In the pheromone traps, 82% were males. In the sticky traps, the sex ratios of both species were more balanced. The phenologies of both I. typographus and P. chalcographus show two peak flight periods. Flight in May/June respresents the overwintered generation, July/August presumably the summer generation. A comparison with reference traps within forest area 700 m north and south of the meteo mast reveals that the proportion of Ips typographus flying out of forest areas varies greatly between the two generations while less than 10% of the overwintered beetles were trapped outside of the forest, more than a third of the summer catches were trapped far away form any potential breeding places. It is suggested that habitat changes (innerforest movements) are mainly performed by the summer generation, while the overwintered beetles are less mobile. From March to September, Trypodendron lineatum was abundant in forest areas, but virtually absent in our traps outside the forest, suggesting a far less dispersive flight behavior. LG GE.

Eidmann, H.H. 1992. Impact of bark beetles on forests and forestry in sweden. J. Appl. Entomol. 114 (2). 193-200. ab The impacts of bark beetles in Sweden and the role and management of bark beetle breeding substrate are discussed. Of the six important species damaging living trees (Tomicus piniperda, Tomicus minor, Hylastes cunicularius, Polygraphus poligraphus, Pityogenes chalcographus, Ips typographus), Tomicus piniperda and Ips typographus have the greatest impact. The damage caused by Tomicus adults feeding in pine shoots is directly related to beetle numbers, which in turn depend on the availability of non-resistant breeding substrate. Intensity of shoot pruning, tree size, and geographic region are important factors determining the extent of losses, which can amouunt to 45% of the annual volume growth. The extent of tree mortality caused by Ips typographus attack depends on interactions between host tree vigour, densities of colonizing populations, and the availability of other, non-resistant breeding substrate. During the latest outbreak, the trees killed represented about 6 million cubic meters of wood. The heaviest losses were reduction of timber quality, unsalvaged timber, and the cost of control measures. The economic impact of reduced growth depends on the shortening of rotation by insect attack and on interest rates. During the 1960s and 1970s bark beetle attacks and their impact increased owing to natural causes and forestry practices. Hereafter, integrated forest protection efforts, based on research, organisation, information, and legislation, reduced bark beetle attacks to a low level. LG EN.

Forsse, E., & Solbreck, C. 1985. Migration in the bark beetle ips-typographus duration timing and height of flight. Z. Angew. Entomol. 100 (1). 47-57. ab Migration by flight is important for the bark beetle I. typographus L. because its normal breeding habitats are ephemeral and scattered. Flight during was recorded on flight altitude measured with suction traps on a TV tower. There is much variation in flight duration between individuals which apparently is not an artifact of the method and which is unrelated to sex, size and environmental conditions earlier in the life of the beetle. The timing of flight is affected by recent environmental conditions. Roughly 10% of the population flies above the forest canopy and have the possibility of travelling considerable distances with winds. The major part of the population seems to fly within the forest (below tree tops), but nevertheless seems able to search large areas during extended and repeated flights over several days. LG EN.

Khansen, T.E., Viik, M.O., & Luik, A.K. 1980. Biochemical changes and cold hardiness in hibernating beetle ips-typographus coleoptera ipidae. Entomol. Obozr. 59 (2). 249-253. ab Seasonal changes in the water content, carbohydrates, fat reserves and cryoprotectants in the beetles I. typographus L. were investigated and their supercooling point determined. The percentage of fat reserves was high (14.1%) in Oct. and changed very little during autumn and winter. The fat reserves were consumed in spring when the temperature of the environment rose over C. Glucose concentration increased until the end of Nov. when the average temperature of the air stayed above C. The glycogen content remained at the same level (3.5%) during this period. A steep decrease in the glycogen and glucose contents was observed from the end of Nov. They are used as energetic substrates during the winter. From March on, the glycogen content increased. The 2nd decrease in the glycogen content was observed in May. Glycogen was used as an energy source in spring for reproduction. The ability to supercool was maximum in Jan. (supercooling point C). A higher supercooling ability in the hibernating period was due to the accumulation of cryoprotectants in the beetles. There are probably dual cryoprotectant systems in I. typographus with glucose as the most important component in the 1st half of the hibernating period and glycerol in the 2nd half. Free amino acids are not involved in the biochemical cryoprotectant reactions in the hibernating beetles I. typographus. LG RS.

Lindelow, A., & Weslien, J. 1986. Sex-specific emergence of ips-typographus coleoptera scolytidae and flight behavior in response to pheromone sources following hibernation. Can. Entomol. 118 (1). 59-68. ab Emergence patterns, sex ratios, and dispersal characteristics of Ips typographus L. (Coleoptera: Scolytidae) emerging from hibernation sites were studied under field conditions. A total of 8666 emerging beetles were caught in 14 tent-traps, covering brood tree stumps at 3 different hibernation sites. Samples of these beetles were sexed at frequent intervals. The proportion of females increased as emergence progressed and the overall proportion of females was 62%. A total of 3433 beetles emerging after hibernation were marked and released on 19 separate occasions. The recapture rates were 13 and 4% in nearby and distant pheromone traps, respectively. Recaptures were recorded at distances of up to 1800 m. Beetles were able to respond and fly to pheromone sources shortly after emergence without prior feeding or prolonged flight activity. Trapping and marking techniques, temporal and spatial emergence patterns, seasonal sex ratio changes, and factors influencing pheromone trap catches are discussed. LG EN.

Lobinger, G. 1994. Air temperature as a limiting factor for flight activity of two species of pine beetles, Ips typographus L. and Pityogenes chalcographus L. (Col., Coleoptera Scolytidae). Anzeiger. Fuer. Schaedlingskunde. Pflanzenschutz. Umweltschutz. 67 (1). 14-17. Issn 0340-7330. ab Single catches of bark beetles in pheromone baited traps were registered by the aid of a new instrument. It consists of an electronical weather station in connection with a pheromone trap with infrared sensors as additional equipment. So it was possible also to register weather data at the moment of every catching event. It could be shown that the flight behaviour of both species of bark beetles was influenced by air temperature. I. typographus did not fly beneath a minimum temperature of 16.5 degree C. There was also an upper limit of 30 degree C for flight activity of this species. P. chalcographus has a threshold of temperatures about 16.8-17 degree C for activity. No upper limit of temperature could be observed up to 35 degree C. Both of them, I. typ. and P. chalc., reacted very sensitive and spontaneous to these temperature thresholds. LG GE.

Luik, A., Khansen, T., & Viik, M. 1980. Role of daily thermo rhythm in the induction of winter dormancy in ips-typographus. Eesti. Nsv. Tead. Akad. Toim. Biol. 29 (2). 109-112. ab Winter dormancy in I. typographus L. is characterized by the ability to acclimate to cold during the autumn as an effect of daily thermorhythm. After 35 days in thermoperiodic conditions (10 h at C and 14 h at, the beetles acclimate to temperatures slightly below C. Their ability to acclimate was higher after a 60-day thermoperiodic effect. The higher the glucose concentration in the beetles, the lower was the supercooling point. LG RS.

Nemec, V., Zumr, V., & Stary, P. 1993. Studies on the nutritional state and the response to aggregation pheromones in the bark beetle, Ips typographus (L.) (Col., Scolytidae). Journal. Of. Applied. Entomology. 116 (4). 358-363. Issn 0931-2048. ab The correlation between nutritional state and behaviour was studied in an overwintering population of bark beetles, Ips typographus (L.). It was found that 3 groups of the bark beetles could be distinguished with respect to their nutrient contents and reactivity to the traps with aggregation pheromone in the field: Group A - newly emerged beetles searching for food ignored the pheromone traps, were shown to have low protein and glycogen contents. Group B - feeding beetles with high lipid and glycogen contents but relatively low protein content probably due to degeneration of flight muscles. They were taken as control with regard of nutrient contents. Group C - beetles, attracted to the pheromone traps, were divided into two subgroups: C1 - beetles with high content of glycogen and lipid but low protein. They represented about 25-30% of captured beetles and they were from local population. C2 - characterized by a low content of glycogen and lipid but high protein, probably due to well developed flight muscles. They represented about 70% and probably belonged to migrating. beetles. A possible correlation between reactivity to pheromones and nutrient reserves is discussed. LG EN.

Nilssen, A.C. 1984. Long range aerial dispersal of bark beetles and bark weevils coleoptera scolytidae and curculionidae in northern finland. Ann. Entomol. Fenn. 50 (2). 37-42. ab Trap logs of spruce (Picea abies) were placed at different distances north of the spruce forests along the Muonio-Kilpisjarvi road in northwestern Finland. At the greatest distance, 171 km (Kilpisjarvi), 3 scolytids were found: Dryocoetes autographus, Hylastes cunicularius and H. brunneus, and the curculionid Hylobius abietis. These were evidently dispersed anemochorously from the Finnish/Swedish forests. At the other sites spruce bark beetles were found at the following maximum distances from the spruce forests: Pityogenes chalcographus and H. cunicularius: 86 km, D. autographus: 52 km, Ips typographus: 43 km (trap log baited with synthetic pheromones), Hylurgops glabratus: 19 km, and D. hectographus: 10 km. Some of the species may have originated from small populations living on nearby non-host trees Pinus sylvestris, but most of them were probably blown by winds or actively flew from the spruce forests. LG EN.

Sanders, W. 1984. The behavior of the scolytid ips-typographus during the flight period. Anz. Schaedlingskd. Pflanzenschutz. Umweltschutz. 57 (7). 131-134. ab In the open air newly emerged beetles showed a very different flight capability. The initial flight was directed by optical structures next to the starting place. The number of caught beetles in pheromone baited traps showed that in the endemic phase the summer generation of I. typographus extended the dispersal flight to deciduous stands. Relative high numbers of beetles were counted in traps on the southern edge of a beech stand at a distance of at least 400 m from the next potential breeding place. Within the beech stand beetles were caught but in a significant smaller number as on the edge. LG GE.

Schopf, A. 1989. The effect of photoperiod on the induction of the imaginal diapause of ips-typographus l. coleoptera scolytidae. J. Appl. Entomol. 107 (3). 275-288. ab The influence of various photoperiods at a constant temperature of C on the emergence rate, gonad maturation, and the respiration rate of the progeny of Ips typographus was examined after periods of adult development between two and six months. While at a long-day conditions of 16L : 8D a linear correlation exists between duration of development and emergence rate, short-day photoperiods of 8L : 16D, 10L : 14D, and 12L : 12D caused the progeny to remain in the brood galleries. The intensity and duration of this effect was influenced by the date of brood initiation and therefore by the quality of brood substratum. In addition short-day photoperiods caused a suppression of gonad maturation during the first four months of beetle's development. An increase in gonad development could be found not before six months. Long-day beetles at suitable brood conditions were already mature after two months; their gonad maturation, however, varied depending on the time of brood initiation. An inhibition of gonad maturation could also be observed in beetles which remained in their logs for four months. A sex-dependent inhibitory effect on gonad maturation was noticed at photoperiods of 12L : 12D. While both females arrested in their logs and those, which had already emerged, showed undeveloped ovaries after four months, males partially had mature accessory glands of their testes according to the date of brood initiation. This premature development of males could also be found in outdoor beetles investigated in February. At this time, in the contrary, ovarion development had not as far proceeded as compared to females in November and was strongly different from those of mature long-day females. A significant difference exists between long-day and short-day beetles with respect to their respiration rates, which were independent of the degree of maturation and the age of development. Individuals reared under short-day conditions had an oxygen consumption reduced by more than one third compared to long-day beetles. Together with their decreased emergence rate and suppressed gonad maturation this represents one main criterion of the induced facultative imaginal diapause of I. typographus. LG GE.

Weslien, J. 1992. Effects of mass trapping on ips-typographus l. populations. J. Appl. Entomol. 114 (3). 228-232. ab The capture rate of Ips typographus in pheromone traps was estimated to be about 30% during 3 years of an outbreak. Tree mortality declined with about 80% during these 3 years. Possible effects of trapping on Ips typographus population size and three mortality are discussed. LG EN.

Weslien, J., & Bylund, H. 1988. The number and sex of spruce bark beetles ips-typographus l. caught in pheromone traps as related to flight season trap type and pheromone release. J. Appl. Entomol. 106 (5). 488-493. ab The influence of season, and pheromone release rate on the number and sex of Ips typographus caught in flight- (barrier), landing- (sticky) , and entering- (pipe) traps were investigated in the field. During the first 6 days of flight in spring the proportion of males among beetles caught flying around, landing on, and entering pheromone-baited pipe traps was estimated to be 41%, 29% and 18% respectively. During this period the proportion of males among beetles caught decreased with time by a ca 20% in all three trap types. The first flight period was probably the time during which most beetles left their hibernation sites. Thereafter the sex ratio was constant over time, corresponding to ca 30% males among beetles caught on the landing traps. All three trap types caught more females at a high release rate of pheromone than at a low release rate. Although the catch of males was higher in the flight traps at the high release rate, there was no effect of release rate on male catch in landing traps and entering traps. The results are discussed in contexts of beetle behaviour, trap technology, and forest protection. LG EN.

Weslien, J., & Lindelow, A. 1989. Trapping a local population of spruce bark beetles ips-typographus l. population size and origin of trapped beetles. Holarct. Ecol. 12 (4). 511-514. ab A method of trapping local populations of Ips typographus was investigated in the field. The size of a population emerging from a hibernation site in the forest litter was estimated using tent traps. This estimate was compared with another estimate where beetles from the population were marked and recaptured in pheromone traps. The estimate of population size with mark-recapture was much higher than the estimate with tent traps, indicating a high degree of immigration. According to calculations only a minor part (less than 20%) of the beetles caught in the pipe traps originated in the local population. Re-emerging parent-adults were marked and released during the second flight period. The recapture rate was 29.8%, almost the same as during the first flight. Immigration during the first and second flight periods was estimated to be of similar magnitude. The results show that it is difficult to suppress local populations of highly mobile bark beetles by trapping. LG EN.

Weslien, J., & Lindelow, A. 1990. Recapture of marked spruce bark beetles ips-typographus in pheromone traps using area-wide mass trapping. Can. J. For. Res. 20 (11). 1786-1790. ab Mark-release-recapture experiments were performed with Ips typographus (L.) populations to estimate recapture rates (number recaptured/number released) in pheromone traps. The recapture rate of bark beetles marked during spring emergence during 2 consecutive years was about 8% in trap groups set 100 m from release sites and decreased to about 2% in trap groups set 1200-1600 m away. The rate at which recapture declined with distance was slower than predicted by a model in which the decrease in recapture depends only on the dilution of released beetles. Sixty percent of the variation in recapture rates was explained by the distance between release and recapture points. The relationship between distance and rate of recapture was used to estimate the rate at which regional beetle populations may be captured using area-wide mass trapping. LG EN.

Weslien, J., Annila, E., Bakke, A., Bejer, B., Eidmann, H.H., Narvestad, K., Nikula, A., & Ravn, H.P. 1989. Estimating risk for spruce bark beetle ips-typographus l. damage using pheromone-baited traps and trees. Scand. J. For. Res. 4 (1). 87-98. ab The risk for damage associated with spruce bark beetle attacks on living trees was estimated in 12 forest districts in the Nordic countries during three years. Pheromone-baited traps and trees were used. Five groups of three traps were deployed annually on fresh spruce clear-fellings in each district. The mean catches within districts and years ranged from 950 and 46,000 beetles per trap group. The standard error averaged 15% of the mean catch. One tree was baited annually at each of five other sites in each district. The mean number of trees colonized by Ips typographus in each district and year ranged from 0 to 5 per site. The standard error was high, averaging 44% of the mean. Inventories of tree mortality within the districts yielded values ranging from 0 to 150 killed trees per km of spruce forest edge. There was a strong linear correlation between mean catches in traps and log-transformed tree mortality (r = 0.82). The correlation between colonization success at tree-baiting sites and tree mortality was weaker (r = 0.59), owing to one deviant observation. The results indicate that pheromone traps and baited trees may be used to assess the risk for damage caused by Ips typographus. LG EN.

Zolubas, P., & Byers, J.A. 1995. Recapture of dispersing bark beetle Ips typographus L. (Col., Scolytidae) in pheromone-baited traps: Regression models. Journal. Of. Applied. Entomology. 119 (4). 285-289. Issn 0931-2048. ab Parent (re-emerged) spruce bark beetles (Ips typographus L., Col. ; Scolytidae) beginning a second host-seeking flight were collected in pheromone-baited traps. These beetles were marked with fluorescent powder of different colors and released from a point source (9-16 June 1989) within a spruce, Picea abies L., forest (Jurbarkas forest district, Lithuania). Some of the marked beetles were recaptured with pheromone-baited traps in two experiments: (1) traps at 10 m and (2) traps 30, 60, 90, and 120 m distances from the release point. Of 5920 and 5030 beetles that took flight in the two experiments, average recapture rates were 5.64 +- 1.17% (+- SEM) on traps at 10 m distance, and 1.62 +- 0.2 1, 0.88 +- 0.23, 0.27 +- 0.08, and 0.03 +-0.03% on traps at the respective distances from 30 to 120 m. Parameters of several regression models were fitted with the Simplex algorithm (SYSTAT statistical software) to recapture data. The best fitting models were those of power, and an exponential form. A discussion of the biological meaning of certain coefficients in the equations is presented with regard to bark beetle dispersal. LG EN.

Zuber, M., & Benz, G. 1992. Investigations on the temporary sequence of the flight activities of ips-typographus l. and pityogenes-chalcographus l. col. scolytidae by means of the commercial pheromone preparations pheroprax and chalcoprax. J. Appl. Entomol. 113 (5). 430-436. ab Traps baited with the commercial population attractants Pheroprax and Chalcoprax, developed to attract the eight-toothed spruce bark beetle, Ips typographus (L.), and the six-toothed spruce bark beetle, Pityogenes chalcographus (L.), respectively were used in 1988-1990 to study the flight activity of these insects and their attraction by the preparations. During the three years of investigations, the dates of emergence and the peaks of the first and the second flight remained almost unchanged. Whereas the Chalcoprax-baited traps captured almost only individuals of P. chalcographus, the traps baited with Pheroprax attracted mainly I. typographus but also a fair number of P. chalcographus. On the average, 60-75% of the P. chalcographus specimens caught by the traps baited with Chalcoprax were females, whereas their percentage in the Pheroprax-baited traps was 20-30% only. Both of these polygamous bark beetles when captured in the traps baited with the corresponding specific attractants exhibited a remarkable predominance of males (50-65%) at the beginning of the first flight period, but this percentage dropped to 25-35% after 2-3 weeks. However, the predominance of the males of P. chalcographus captured in Pheroprax-traps either remained high (65-90%) or did not develop below 60% (except in July 1990). It was shown that the distance of Chalcoprax-baited traps from the Pheroprax-baited traps could influence the number and the sex-ratio of P. chalcographus in the Pheroprax-baited traps, the number being increased in the presence of Chalcoprax. The potential components responsible for attraction of the males in the traps baited with Chalcoprax or Pheroprax are suggested. LG GE.

Zumr, V. 1982. Flight activity of the spruce bark beetle ips-typographus to pheromone traps coleoptera scolytidae. Acta. Entomol. Bohemoslov. 79 (6). 422-428. ab Flight activity of the spruce bark beetle, I. typographus (L.), was monitored from 1979-1981 in spruce stands 460-600 m a.s.l. (above sea level) in southern Bohemia (Czechoslovakia), by means of Pheroprax pheromone traps. The number of males decreases and the number of females increases as the season advances. The prevalence of females flying to the traps is coincident with the swarminng peak; females made up 58.5% of the total number of attracted beetles. Subsequent to swarming flights (= attacks) of the 1st generation and beginning of swarming caught after the swarming-peak partly deposited their eggs and represented 3.8-28.6% of the total number of collected females. LG EN.

Zumr, V. 1982. The data for the prognosis of spring swarming of main species of bark beetles coleoptera scolytidae on the spruce picea-excelsa. Z. Angew. Entomol. 93 (3). 305-320. ab The release and spring swarming of Ips typographus (L.), I. amitinus Eichh. and Pityogenes chalcographus (L.) was observed in 3 variants of spruce stands (a clearing, sparse and dense spruce stand). The release and spring swarming of the bark beetles was observed using traps and special trap devices placed into spruce logs. Spring swarming was observed beginning with the insects leaving overwintering sites. The effect of maximum day temperature (tmax) of the soil, of the phloem and of air on the release and swarming was demonstrated. On the basis of measured temperature data, release and spring swarming was determined by the sum of effective temperature (.SIGMA.Et). When leaving overwintering sites, the bark beetles appeared 1st from suspended logs in the margin of the stand and from the soil litter in photoelectors in the clearing. Beetles left the phloem of the suspended logs in the margin of the stand 14-16 days soon in comparison to the photoelectors in the clearing and 11-13 days sooner than inside the stand in comparison with photoelectors in the sparse spruce stand. I. typographus spring attack started with the trap logs and landings in the clearing, 1-2 days later in the sparse stand and 3-5 days later in the dense spruce stand in comparison with the clearing. I. amitinus and P. chalcographus spring attack occurred 0-1 day later in the sparse forest and 0-2 days later in the dense spruce forest. The swarming conditions for each of the 3 bark beetle species are discussed. LG EN.

Zumr, V. 1987. Reduction of mass outbreaks in spruce bark beetle ips-typographus l. coleoptera scolytidae by pheromone traps. Lesnictvi. Prague. 33 (1). 49-64. ab We evaluated the use of pheromone traps in spruce stands of Southern Bohemia (Czechoslovakia) in the period 1983-1985. The average number of 11615 pheromone traps was used every year to catch spruce bark beetles; the average number of entrapped spruce bark beetles made 27 124,000 imagoes a year. The average maximum number of bettles caught per 1 trap was 69 100 and the average minimum number of beetles caught per 1 trap ranged from 0 to 10 imagoes of spruce bark beetle. The total numbers of spruce bark beetles caught in pheromone traps over the period of observation are given in Tabs. I-III and in Fig. 3. In spring months the pheromone traps caught on the average 38.7 to 67.2% imagoes of spruce bark beetle; in summer months 28.1 to 42.0% in sister generations it made on the average 2.6 to 6.7% spruce bark beetles out of the total number of individals caught over the growing season. In hilly regions, the highest numbers of spruce bark beetle imagoes were recorded at the localities with eastern (19.9%) and south-eastern (16.4%) exposures, in mountainous regions at the localities with south-eastern (22.8%) and southern (18.9%) exposures; the percent numbers relate to the total numbers of individuals caught at all exposures. The lowest numbers of spruce bark beetles both in the hilly and the mountainous regions were caught at the localities with northern aspects (1.2-4.6%). At 250 investigated localities, 40.4% of trees in the vinicity of pheromone traps were invaded in 1983, 12.8% of trees in 1984 and only 7.2% of trees in 1975 (Tab. IV) . In this investigated region, 117 020 m3 of wood invaded by bark beetles were processed on the average every year. The total volume of wood invaded by bark beetle and that had to be processed is given in Tabs. I-III and in Fig. 4. The volume of wood invaded by spruce bark beetles and of processed timber decreased in 1985 by 57.2% in comparison with the year 1984. In the given region of Southern Bohemia we succeeded by pheromone traps combined with other methods (trap trees, intensive removal of invaded trees and their haulage out of the forest) in destroying the large numbers of spruce bark beetle individuals and thus reducing the mass outbreak of this pest. At the localities where the catch of spruce bark beetles in pheromone traps was accompanied by the felling and removal of trees invaded by bark beetles, the invasion of this pest decreased by a fourth on the average in the following years. The advantage of pheromone traps is that large numbers of beetles can

Zumr, V. 1990. The migration of spruce bark beetle ipstypographus l. coleoptera scolytidae in spruce stands. Lesnictvi. Prague. 36 (6). 449-455. ab In spruce strands situated in the area of South Bohemia trials were performed concerning the migration of marked adults of spruce bark beetle. In total 44 pheromone traps were used for investigations, placed in circles at distances of 400, 800 and 1200 m. In the spring season 77.0% of individuals of spruce bark beetle were caught out of the total number of marked spruce bark beetles which were let fly. The highest entrapment was recorded in the span of 20 days since release when abut 40% of all released marked spruce bark beetles were caught. The respective percentages of individuals entrapped out of the total number of marked spruce bark beetles to distances of 400, 800 and 1200 m: 39.6; 53.2 and 7.2%. In the summer season 49.5% individuals of spruce bark beetle were caught out of the total number of released marked beetles. The highest entrapment of beetles was recorded in the span of 40 days after release, but also in the subsequent decades the entrapment was active. To distances of 400, 800, and 1200 m, 14.2%, 62.5% and 23.3%, respectively, of individuals were caught out of the total number of marked spruce bark beetles. These results have demonstrated that in the summer season the spruce bark beetles are flying more days and to greater distances than they do in the spring season. LG CZ.

Zumr, V. 1991. The behaviour of spruce bark beetle ips-typographus l. coleoptera scolytidae during flight time in mixed forest stands. Lesnictvi. Prague. 37 (8-9). 669-675. ab In the ecosystems of mixed stands of beech and spruce in Southern Bohemia (Czechoslovakia) trials were made to investigate the behaviour and orientation of spruce bark beetle (Ips typographus L.) during flight time. Marked imagoes of spruce bark beetle and pheromone traps located in forest stands at distances of 200, 400 and 1000 m were investigated. Out of the total number of marked spruce bark beetles only 65.6% individuals were caught in pheromone traps. The highest numbers of individuals was caught in pheromone traps at a distance of 1000 m from the place of release 67.8%; at distances of 400 m and 200 m the percent of entrapped beetles made 18.8% and 13.4% of the total number of caught marked spruce bark beetles, respectively. The number of entrapped beetles in dependence on exposure: western exposure 45.5%, eastern exposure 37.5%, southern exposure 12.9% and northern exposure 4.1% of the total number caught marked spruce bark beetles. During flight time of marked beetles, the highest catch of spruce bark beetles was recorded on to the first day after release them fly, on the following days it was decreasing. Four days after release, no marked spruce bark beetles was caught in pheromone traps. LG CZ.