LABORATORY EVALUATION OF CARABID BEETLES (COLEOPTERA, CARABIDAE) AS PREDATORS OF DIAMONDBACK MOTH (LEPIDOPTERA, PLUTELLIDAE) LARVAE

Consumption of diamondback moth, Plutella xylostella (L.), larvae by 2 4 species of adult carabids and 2 species of carabid larvae was invest igated using small containers in a laboratory. Thirteen species of adu lt carabids were evaluated for their suppressive effect or: diamondbac k moth larvae using small enclosed arenas simulating field conditions. Consumption by adult carabids varied from zero 4th instars per indivi dual per day of each sex of Amara simplicidens Morawitz to 23/d for a female Chlaenius posticalis Motschulsky. Larvae of Chlaenius micans (F .) and C. posticalis consumed approximate to 191 and 92 early 4th inst ars of diamondback moths per individual, respectively, through the ent ire larval period. These larvae were often observed in cabbage heads. In the enclosure experiment, C. micans, C. posticalis, and Dolichus ha lensis (Schaller) caused >95% mortality for diamondback moth larvae du ring 4-d trials. Pterostichus planicollis (Motschulsky) caused 71-77% mortality; the other 9 species in 6 genera, however, contributed <20% to mortality. The high prey suppression by C. micans, C. posticalis, a nd D. halensis can be attributed to the beetles habit of climbing plan ts as well as high consumption rate. These results indicate that C. mi cans and C. posticalis (particularly the larvae of these species) can be important predators of diamondback moth larvae; they have high cons umption rates and the habit of climbing plants in both immature and ad ult stages.