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Scolytidae (Col.) an Pinus ‐Arten in Mittelamerika V. Das Massenauftreten von Dendroctonus adjunctus Blandf. in Guatemala (8. Beitrag zur Forstentomologie Mittelamerikas)
Author(s) -
Schwerdtfeger F.
Publication year - 2009
Publication title -
zeitschrift für angewandte entomologie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0044-2240
DOI - 10.1111/j.1439-0418.1960.tb01363.x
Subject(s) - infestation , outbreak , pinus <genus> , biology , forestry , geography , ecology , botany , virology
Summary In the highlands of Guatemala where large forests of Pinus rudis Endl. are growing, great damages caused by outbreaks of Dendroctonus adjunctus Blandf. have been observed since more than 40 years, though they probably have been noted since the time man began to exploit the forests. The beetles attack healthy trees which try to offer resistance by secreting fluid resin. At the entrances, characteristic pitch tubes are formed. After a successful infestation the withering, dying and dropping of the needles follows rather slowly. The damages caused by D. adjunctus are of decisive importance for the Guatemalan forestry. While nearly all former authors consider D. adjunctus as chiefly secondary, it could be prooved that its attacks are absolutely primary. The flying beetles ready to oviposit are attracted by freshly cut pine trees, but instead of entering the felled trunks they infest on the contrary healthy trees standing in the next neighbourhood and probably within the odour sphere of the pine trunks. Pruning, fire damages and infestation by Dendroctonus valens Lec. may allure the beetles, too. A local infestation enlarges for a short time, but regularly goes out soon. The causes for the quick termination of the local outbreak are the flying off of the young beetles, the scattering of the attacks, the unfit nutrition conditions for the young larvae, the atmospheric conditions and perhaps the enemies out of the biotic environment. Other measures of lumbering or windfalls may kindle again the outbreak. Thus, by repeated flaring up and enlarging of local infestations the vast areas of damage came into being. The damages can be prevented by restricting as far as possible the cultivation of the only endangered pine species Pinus rudis and by carrying out the lumbering in such a manner that it does not cause a concentration of the beetles. The end of direct control measures has to be the destruction of the brood within the trunk before the young beetles fly out. This end is reached by cutting and disbarking the infested trees at the right time; in addition to that the measures can be furthered by taking advantage of the sun heat, by burning the bark and by singeing the trunks.