Reproduction abilities of Ips typographus (L.) (Coleoptera: Curculionidae, Scolytinae) in the stands damaged by the wind in 2013 in the Kościeliska Valley (Tatra National Park)

Abstract

At the end of 2013, strong wind destroyed spruce stands on large areas of Kościeliska Valley in Tatra Mts. in Poland. In 2015-2017, 304 bark samples were collected from 106 spruces; 25 cm × 25 cm large samples were taken from 2 or 4 sections of infested trees in July/August each year. The infestation density, sex ratio, length of maternal galleries, number of progeny and impact of natural enemies were recorded. The infestation density in individual years was 0.79-0.86 mating chambers per dm 2 , the average length of maternal gallery (55.2-56.6 mm) did not differ between years, The average number of progeny per female from 3-year pooled data was 18.22, the highest in 2015 (27.4) then collapsed to 15.5-16.8. The gallery systems with 2 females, in which the reproduction success was the highest, dominated (62.6%). The frequency of parasitoids or entomopathogens was very low (2-20% mortality rate in 19 bark samples). Possible reasons of relatively low reproduction success regardless generally favourable breeding conditions and its collapse after first year, such as high infestation density and low survival rate of larvae because of climatic conditions (drought), are discussed. Taking into account the described population features, very intense tree mortality and mechanisms known from the other wind events, further development of the outbreak can be expected in this area.

The European spruce bark beetle Ips typographus (L.) in wind-damaged stands of the eastern part of the Tatra National Park – the population dynamics pattern remains constant

“…The share of females in 2018 (61%) was similar to the level recorded in the Kościeliska Valley in 2015-2016 (63-64%), thus indicating the tendency for further development of I. typographus outbreak (Lobinger 1996; Grodzki and Gąsienica Fronek 2017b). The share of females in the populations attacking spruces in Tatra, Gorce and Beskid Żywiecki during progradation and culmination phase of the outbreak was slightly higher, reaching 64-69% (Grodzki et al 2006b(Grodzki et al , 2007(Grodzki et al , 2014.…”

“…The share of females in the populations attacking spruces in Tatra, Gorce and Beskid Żywiecki during progradation and culmination phase of the outbreak was slightly higher, reaching 64-69% (Grodzki et al 2006b(Grodzki et al , 2007(Grodzki et al , 2014. On the other hand, the effective reproduction rate in 2018 (19.7 eggs/larvae per 1 female) was lower than in the Kościeliska Valley in the first year of the outbreak (27.4 eggs/larvae per 1 female), but higher than the mean value calculated using the models based on field data (Grodzki and Gąsienica Fronek 2017b); nevertheless, the high infestation density and early started development of pre-imaginal stages in the spring indicate the risk of fast increase in I. typographus population level in this newly appearing outbreak area. Also, the increasing frequency of P. chalcographus, an important bark beetle species that contributes to the spruce mortality (Grodzki 1997(Grodzki , 2004, as well as low level of parasitism, should be seen as additional factors that affect the threat to those stands.…”

“…A single plot consisted of 20 numbered living Norway spruces (240 in total) that were regularly checked during the growing season in order to identify and register the successively appearing trees infested by I. typographus. Some of them were then examined in order to acquire the main parameters of infestation, such as the infestation density, the sex ratio and effective reproduction rate, as the traits that could indicate the outbreak tendencies of the observed population (Lobinger 1996; Grodzki et al 2006cGrodzki et al , 2014Grodzki and Gąsienica Fronek 2017b). For this purpose, two procedures were applied, depending on the nature protection status.…”

Interaction of disturbance agents on Norway spruce: A mechanistic model of bark beetle dynamics integrated in simulation framework WINDROT

“…increased in the top part. Recent study by Grodzki and Gąsienica Fronek (2017) studying infestation rates and reproduction success under several bark thicknesses reported very minor effects on both variables. However, the study was conducted only until 2mm bark thickness and do not therefore offer information whether colonization and reproduction is successful under bark thickness of less than 2mm.…”

Preemergence mating, inbreeding, and their consequences in the bark beetle Ips typographus

“…4]). The latter is closely correlated with female productivity (Anderbrant 1990;Grodzki and Wojciech 2017). To estimate postlarval mortality, we counted the number of larval galleries in each maternal gallery and calculated the difference between the number of larval galleries and the number of adult offspring.…”