Some Factors Influencing Bollworm Populations and Damage

Abstract

Timely applications of heavy dosages of Ca arsenate control the bollworm, but under certain conditions cotton dusted with Ca arsenate becomes more heavily infested with bollworm eggs and larvae than undusted cotton. The increase in bollworm infestations is frequently associated with increased aphid populations following dusting, and may be due partially to the attraction of bollworm moths to aphid honey-dew. Laboratory and field cage tests at Waco, Texas with certain predators showed that when aphids were abundant the predators permitted larger numbers of bollworm eggs to hatch and larvae to survive than when aphids were absent. 12 spp. of predaceous insects found on cotton readily fed and survived on bollworm eggs and some consumed large numbers of eggs. The average consumption by individuals of 3 spp. was > 21 eggs per day, and one individual of Hippodamia convergens consumed 275 eggs in a day. An increase in aphid infestation resulting from Ca arsenate dusting seems to upset the normal food balance between bollworm eggs and young larvae and various predators, and this may be an important factor causing increased bollworm populations in dusted cotton.