Influence of cotton irrigation frequency on the duration of the prepupal and pupal stages of non-diapausing pink bollworms [Pectinophora gossypiella]

Prepupal and pupal stages of non-diapausing pink bollworms, Pectinophora gossypiella (Saunders) were observed in cotton fields during the summer at Phoenix, AZ to determine the effect of irrigation frequency on developmental duration. The time required by these soil-inhabiting stages ranged from a minimum of 11 days during July in relatively dry plots that received water once every 3 wk (mean soil temperature = 27. 7°C) to as long as 17 days during Aug. in cotton plots where soils remained cooler (mean temperature = 22.5°C) as a result of weekly irrigations. A computer simulation of development consistently underestimated observed durations when either standard weather bureau or shelter temperatures instead of actual field soil temperatures were used as model inputs.