THE ROLE OF THE CORPORA ALLATA IN THE DEVELOPMENT OF LEUCOPHAEA MADERAE (ORTHOPTERA)1

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Abstract
Extirpation of the corpora allata was performed at various stages of development in Leucophaea maderae (Panchlorinae, Orthoptera). In 8th (last) instar nymphs the operation had no visible effect on development. Allatectomy at stages earlier than the last caused an abbreviation of development which resulted in animals with adult-like characters ("adultoids"). In operated 7th instars the following nymphal molt was suppressed, and the animals emerged as adultoids, resembling normal adults except for their smaller size and comparatively shorter wings. Allatectomized 6th or 5th instars resulted in "preadultoid" stages which showed less adultoid differentiation and required an additional molt before becoming adultoids. The "critical period," i.e., the time at which within a given nymphal stage an effective concn., of the corpus allatum hormone (juvenile hormone) is reached, lies near the beginning of the 2d half of the intermolt period. The interaction of hormonal factors and tissue responsiveness in the control of insect development is discussed.