Laboratory Evaluation of Carabid Beetles (Coleoptera: Carabidae) as Predators of Diamondback Moth (Lepidoptera: Plutellidae) Larvae

Abstract

Consumption of diamondback moth, Plutella xylostella (L.), larvae by 24 species of adult carabids and 2 species of carabid larvae was investigated using small containers in a laboratory. Thirteen species of adult carabids were evaluated for their suppressive effect on diamondback moth larvae using small enclosed arenas simulating field conditions. Consumption by adult carabids varied from zero 4th instars per individual 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 a191 and 92 early 4th instars of diamondback moths per individual, respectively, through the entire larval period. These larvae were often observed in cabbage heads. In the enclosure experiment, C. micans, C. posticalis, and Dolichus halensis (Schaller) caused >95% mortality for diamondback moth larvae during 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, and D. halensis can be attributed to the beetles habit of climbing plants as well as high consumption rate. These results indicate that C. micans and C. posticalis (particularly the larvae of these species) can be important predators of diamondback moth larvae; they have high consumption rates and the habit of climbing plants in both immature and adult stages.