Phenology and degree day requirements of Cerotoma trifurcata (Coleoptera: Chrysomelidae) in Ontario

ESA 2011

Cara McCreary                                                                                                                                  

 

Abstract

            Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), bean leaf beetles, are leaf feeding beetles that feed on plants belonging to Fabaceae.  Adult feeding on leaves, stems, pods and peduncles and larval feeding on roots and rhizobium nodules can impact soybean health and production.  Phenology of C. trifurcata, although unknown in Ontario, differs throughout North America.  Cage studies were conducted in soybean fields to determine the number of generations that occur in three counties in southern Ontario.  Cages were artificially infested with C. trifurcata and destructively sampled every 10 days.  Soil and soybean root samples collected throughout the soybean growing season showed one cycle of eggs, larvae and pupae.  Field-collected C. trifurcata were reared in environmentally controlled growth chambers using five temperature regimes.  Mating pairs of adults were placed in containers with soybean foliage.  Eggs collected from adult containers were distributed amongst the different temperatures and larvae were fed cowpea cotyledons until pupation occurred.  Complete generations were successfully reared at four of the five temperatures and time required for life stage development was recorded.  Degree day requirements for development of C. trifurcata from egg to adult were established from temperature data recorded within cages and from beetles reared in growth chambers.