Diversidad y control biológico de insectos - CyberTesis UACh ...

Summary.
The effects on generalist predators of the insecticide lambda-cyhalothrin and a new
biopesticide based on Beauveria bassiana spores were studied in the 2003 growing season
(October to December, Southern spring) in Valdivia, Chile. Both pesticides are targeted
against larvae of Dalaca spp. (Lepidoptera: Hepialidae), a complex formed by Dalaca
chiliensis, Dalaca pallens and Dalaca variabilis. Sampling revealed an assemblage of 11
carabid species and two spider families (Lycosidae and Gnaphosidae). In order of
abundance, the carabid species detected were Ferionomorpha nebroides (45%), Allendia
chilensis (20%), Argutoridius chilensis (13%), Ferionomorpha aerea (11%) and
Ceroglossus chilensis (6%). Other six species accounted by less than 1% each (Metius
flavipes, Mimodromites cyaneus, Parhypates sp., Trechisibus angularis, Calosoma vagans
and Trirammatus unistriatus). Spider families were almost equally represented. In the first
two sampling dates, low numbers of predators precluded to detect effects of treatments,
except for F. nebroides. Activity of predators increased in time and negative effects of
lambda-cyhalothrin were detected on F. nebroides, F. aerea, Lycosidae and Gnaphosidae.
Most of decreases were detected by day 30 after spraying. Differences did vanish by day 60
on spiders, but they persisted on some carabids. Inundative release of B. bassiana spores
did not affected any taxa, being a good potential alternative to the broad-spectrum
insecticide, which disrupted the generalist predator assemblage severely.
Keywords.
Inundative biological control; non-target; lambda-cyhalothrin; Carabidae; Lycosidae;
Gnaphosidae.
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