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

ABSTRACT
About 10% of Southern Chile pastures (ca. 300.000 ha) are sprayed with insecticides every
year, which are targeted on a native hepialid cutworm, Dalaca pallens (Bl.). Some of these
insecticides are not species-specific, increasing the biodiversity declining in process since
the 19th century, when forests begun to be replaced by pastures. The D. pallens biological
control using Beauveria bassiana (Bals.) Vuill. strain QU-B931 has shown to be as
efficient as the current chemical control, but potential non target effects are unknown. The
genetic diversity of B. bassiana was assessed by sequencing a intergenic nuclear region
called B loc. Once the selected strain was characterized, the non target effects of lambda-
cyhalothrin and B. bassiana spores on the arthropofauna were evaluated in winter and
spring. The side effects were evaluated at three different levels: single taxa (carabids and
arachnids); guilds (predators, herbivores and decomposers) and arthropod community. A
sample of 97 strains collected along the country was separated into 20 genetic groups, some
of which are restricted to some regions (for example Eastern Island), while others are
distributed across the country. This molecular technique allowed to discriminate the
selected strain from the rest of the sample. In the other hand, the insecticide lambda-
cyhalothrin affected four predators (two carabid beetles and two spiders), decreased the
predator guild and decreased the diversity, species richness and evennes of the whole
community. However, it did not affect the decomposer and herbivore guilds. The biological
control based on B. bassiana did not affected any species, guild or the community and
arises as an alternative with lower environmental effects than the current control.
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