Figure 2. Effect of (conspecific) crowding (low (50 insects/jar) or high (150 insects/jar) initial density) on the population growth of two species of stored grain beetles (Sitophilus zeamais and Rhyzopertha dominica) reared on maize grains treated with increasing doses of the organophosphate insecticide fenitrothion.

Dotted lines indicate the concentration at which population growth is zero (i.e., does not occur). Each symbol represents the results of an experimental replicate.