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 25.degree. C. As a comparison, emerging
brood adults were collected and held at 25.degree. 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 25.degree. 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 4.degree. 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.
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 25.degree. at the surface down to
13.8.degree. C at a depth of 4 cm also slightly increased the survival of
beetles compared with a constant 25.degree.. 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.
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 0.degree. C. Glucose concentration increased until
the end of Nov. when the average temperature of the air stayed above 0.degree.
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 -25.8.degree. 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.
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 17.degree. C and 14 h at 6.degree.), the beetles acclimate to temperatures
slightly below 0.degree. 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 20.degree. 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.