On the capacity of Bacillus thuringiensis to spread in insect populations

A number of untreated larvae ofEphestia kuehniella andPieris brassicae were confined with some larvae of the same species that had recently been infected withBacillus thuringiensis. The majority of the last category died within a few days. Although healthy, diseased and dead specimens were kept together for several days, scarcely any larva of the healthy group became diseased or died by the action of the bacterium. It was concluded thatB. thuringiensis does not spread easily.Samenvatting Onbehandelde rupsen vanEphestia kuehniella andPieris brassicae werden samengebracht met een aantal rupsen van dezelfde soort, die kort tevoren anaal, resp. oraal geïnfecteerd waren met een suspensie vanB. thuringiensis. Van de laatste categorie stierven de meeste na enkele dagen. Ofschoon de gezonde, zieke en dode rupsen daarna nog enige weken werden samengehouden, trad er onder de onbehandelde rupsen praktisch geen sterfte op, die veroorzaakt was door bacteriën.