Hymenopterous parasites of lps spp. bark beetles (Coleoptera:Scolytidae) in Virginia
The pine engraver beetles (~ spp.:Coleoptera:Scolytidae) may be serious pests depending on certain prerequisi.te conditions. In their secondary or "normal" role they breed in slash and damaged, dying, and dead trees. The broods emerging from these sources normally attack similar material....
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| Format: | Others |
| Language: | en |
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Virginia Tech
2014
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| Online Access: | http://hdl.handle.net/10919/40271 http://scholar.lib.vt.edu/theses/available/etd-10302008-120438/ |
| Summary: | The pine engraver beetles (~ spp.:Coleoptera:Scolytidae) may be serious pests depending on certain prerequisi.te conditions. In their secondary or "normal" role they breed in slash and damaged, dying, and dead trees. The broods emerging from these sources normally attack similar material. When such material is scarce due to cessation of cutting operations in mid-season or when conditions are especially
favorable for brood development, an excess of beetles is often produced which, due to the lack of more suitable material, attack healthy trees. Repeated attacks cause these trees to succumb and die. When normally healthy trees are weakened by fire, flood, defoliation, drought, stagnation, etc., then they become more acceptable host material for successful engraver attacks. When the production of a very large
number of beetles in "normal" breeding material coincides with physiological stress in "healthy" trees, then population explosions can occur. When large numbers of beetles and low host vigor do not coincide, spot kills cornnon1y occur. According to Thatcher (32), spot kills, although not conspicuous, add up to large volumes of timber loss each
year. === Ph. D. |
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