Development of the bait principle for boll weevil control IV. Field tests with a bait containing a feeding stimulant and the sporozoans Glugea gasti and Mattesia grandis

Abstract

Bait containing feeding stimulant and one of two protozoan pathogens ( Mattesia grandis or Glugea gasti) was tested against field populations of boll weevils ( Anthonomus grandis) in the fall of 1966 throughout the season in 1967. In 1966, the weevils that subsequently diapaused responded well to the bait since 60–80% had ingested the red marker dye. Also, although the quantity of the pathogen was limited, both diseases were found in the populations. In 1967, 50–70% of the weevil population present in late June and early July (overwintered weevils) ingested bait containing G. gasti, and as many as 80% were diseased. In contrast, the F 1 and ensuing reproducing generations present from mid-July through August did not respond well: only 2–19% were marked, and only 11–25% were diseased. Then after August 31, as the weevils began to enter diapause, the population again responded well, and 50–70% were marked and diseased. Also, over 60% of the weevils subsequently collected from woods trash from winter hibernation sites were marked and diseased. The treatment with the pathogens in 1967 caused 96% winter mortality of boll weevils compared with 84% in nearby untreated areas. In addition, large populations of insect predators were found in the treated area, and several gallons of one species were collected in samples of woods trash examined in April 1968.