Učinkovitost ulova smrekovih podlubnikov v dvojne in trojne kontrolno-lovne pasti

Osmerozobi smrekov lubadar (Ips typographus) in šesterozobi smrekov lubadar (Pityogenes chalcographus sta najpomembnejša škodljivca navadne smreke (Picea abies) v osrednji Evropi in tudi v Sloveniji. Kontrolno-lovne pasti, opremljene s feromonskimi vabami, uporabljamo za ocenjevanje številčnosti smrekovih podlubnikov. Cilj raziskave je bil izračunati povprečno razmerje (mediano) ulova osmerozobega smrekovega lubadarja in šesterozobega smrekovega lubadarja med dvojnimi in enojnimi ter trojnimi in enojnimi kontrolno-lovnimi pastmi. Za ta namen smo uporabili podatke s spremljanja številčnosti smrekovih podlubnikov v režastih pasteh vrste Theysohn, tj. uporabili smo podatke iz 19.140 enojnih pasti, 4.347 dvojnih pasti in 991 trojnih pasti, ki jih je Zavod za gozdove Slovenije spremljal v letih 2013–2021. V dvojno past se je povprečno ujelo 1,17-krat več osebkov I. typographus kot v enojno. Ulov šesterozobega smrekovega lubadarja v dvojno past je bil v povprečju enak kot v enojni pasti. Ulov osmerozobega smrekovega lubadarja v trojno past je bil v povprečju 1,58-krat večji kot v enojno. V trojno past se je povprečno ujelo 1,54-krat več osebkov P. chalcographus kot v enojno. Preverili smo tudi vpliv izbranih dejavnikov na razmerje ulova v pasteh: (1) razlika v začetku spremljanja (2) razlika v nadmorski višini (3) pasti je čistila ista oseba (4) oddaljenost od druge pasti (5) razlika v razdalji do najbližjega žarišča. Na mediano razmerja ulova je najbolj vplivala oddaljenost od drugih pasti. Na mediano razmerja ulova I. typographus v trojno past sta zaznavno vplivala tudi začetek spremljanja in razlika v nadmorski višini med primerjanima pastema. Ničen vpliv na mediano razmerja med trojno in enojno pastjo je imel pogoj, da je pasti čistila ista oseba. Izračunana povprečja bomo uporabili za točnejši preračun kumulativnega ulova v dvojne in trojne kontrolno-lovne pasti na eno past, saj smo za to doslej uporabljali konstanti dve za dvojne in tri za trojne pasti, kar je bistveno več od dejanskih razmerij. To bo pripomoglo k zanesljivejšim ocenam o prenamnožitvah na lokacijah pasti, kjer uporabljamo podatke iz spremljanja ulova v dvojne in trojne kontrolno-lovne pasti. The European spruce bark beetle (Ips typographus) and the six-toothed spruce bark beetle (Pityogenes chalcographus) are the most important pests of spruce (Picea abies) in Central Europe and also in Slovenia. The aim of the study was to calculate the ratio (median) of catches of European spruce bark beetle and six-toothed spruce bark beetle between double vs. single, and triple vs. single pheromone traps. For this purpose, we used the data from the monitoring of spruce bark beetles in slit barrier pheromone traps of type Theysohn i.e., we used the data from 19,140 single traps, 4,347 double traps, and 991 triple traps monitored by the Slovenia Forest Service in the period from 2013 to 2021. A double trap caught 1.17 times more specimens of I. typographus than a single trap. The catch of six-toothed spruce bark beetle into double traps was on average the same size as in a single trap. The catch of European spruce bark beetle in a triple trap was on average 1.58 times larger than in a single trap. On average, 1.54 times more specimens of P. chalcographus were caught in the triple trap than in the single trap. We also examined the influence of selected factors on trap catch ratios: (1) the difference in the start of monitoring (2) the difference in elevation (3) the traps were monitored by the same person (4) the distance to another trap (5) the difference in distance to the nearest outbreak area. Distance to another trap had the greatest effect on average catch rates. The onset of monitoring and the difference in elevation between the compared traps also had a noticeable effect on the median catch ratios of I. typographus in the triple trap. The factor that the traps were cleaned by the same person did not affect the median ratio between the triple and single traps. We will use the calculated averages to more accurately convert the cumulative catches to double and triple control traps per trap, as we have previously used constants of 2 for double and 3 for triple traps, which are significantly higher than the actual ratios. This will contribute to more reliable estimates of population size at trap sites, for which we also use catch monitoring data in double traps and triple traps.