Tuesday, March 29, 2011

Fuglekasser for trivsel og nytte


Det er vår i lufta og på tide å få opp fuglekassene. Disse våre venner er viktige trivselsskapere og nyttige medhjelpere for å holde insektpopulasjoner i sjakk. Nå bekrefter forskning at fuglekasser er et enda mer effektivt tiltak enn man hittil har trodd. En ny undersøkelse viser at hele 40 prosent av larvene som ble angrepet av predatorer døde, selv om de ikke ble spist. Videre produserte de som overlevde færre avkom.
Caterpillars are a target of pest control, as they destroy food crops by eating the leaves of cabbages and other vegetables. This new study, however, suggests that natural predators, such as farmland birds, do not necessarily have to consume large numbers of insects, to have a significant effect on the size of the population. Researchers found that 40% of caterpillars that defended themselves from predators by regurgitating food, died before transforming into a butterfly, despite successfully surviving the initial attack.
The study also showed that on average large caterpillars have 60 eggs, but those that used their defences against daily predator attacks produced approximately 30 eggs. It is thought that this effect could be widespread amongst herbivorous insects, suggesting that predators may have a larger impact on reducing the population of agricultural pests than previously thought.- Science Daily. Insects That Deter Predators Produce Fewer Offspring
Jeg husker en film fra Kina om hvordan formann Mao beordret sitt folk om å drepe all småfugl fordi de spiste matkornet. Resultatet var naturligvis at skadeinsektene eksploderte i antall. Dessverre deler vårt industrialiserte jordbruk Maos syn om at vi er i kamp mot naturen, heller enn at vi skal samarbeide med den.

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