Effects of Noncatastrophic Control Technologies that Alter Life History Parameters on Insect Population Growth: A Simulation Study

Abstract

I investigated the effects of noncatastrophic control technologies that alter life history parameters (such as the use of resistant plant varieties) on the growth of insect populations. I used a computer model to simulate population dynamics of the flat grain beetle, Cryptolestes pusillus (Schonherr). The effects of increasing duration of larval development (by 5, 10, 15, or 20 d) or decreasing fecundity or larval survival (by 25, 50, or 75%) on population growth were simulated. Growth curves for populations with reductions in fecundity or larval survival were nearly identical. The effects of decreasing fecundity or larval survival were apparent during the first generation, whereas the effects of increasing duration of larval development did not become apparent until the second generation. Altering any of the life history parameters resulted in as much as 99% reduction in population levels at constant temperatures and as much as 87% reduction in population levels at actual temperatures in a grain bin. The results indicate that use of control technologies that cause even a small change in a life history parameter may have a significant effect on population growth when applied over a growing or storage season. The combination of such technologies with other methods of control may improve the cost effectiveness of pest management techniques, even if the noncatastrophic control techniques do not provide adequate control when used alone.