Insect Biochem. Vol. 21, No. 6, pp. 573-581, 1991 0020-1790/91 $3.00+ 0.00 Printed in Great Britain.All rightsreserved Copyright© 1991 PergamonPressplc DEVELOPMENT OF FUNCTIONALLY COMPETENT CABBAGE LOOPER MOTH SEX PHEROMONE GLANDS JULIET D. TANG, WALTERA. WOLF, WENDELLL. ROELOFS* and DOUGLAS C. KNIPPLE Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, U.S.A. (Received 10 October 1990; revised and accepted 2 May 1991) Abstract--Unlike some moths, pheromone production in Trichoplusia ni is not regulated by a pheromone activating neuropeptide. Rather, competency to produce pheromone apparently is linked with changes in the ecdysteroid titer that occur late in metamorphosis. In contrast to adult pheromone glands, glands from pharate adults 2 days before eclosion were non-competent, and (1) had undetectable levels of the pheromone, (Z)-7-dodecenyl acetate, and pheromone-specific intermediates, (2) showed little or no conversion of radiolabeled substrate to product in enzyme assays of fatty acid synthetase, A11 desaturase, and acetyltransferase, and (3) failed to incorporate radiolabeled acetate into pheromone in gland culture. Glands 1 day before adult eclosion exhibited low titers of pheromone and the intermediate, (Z)-I 1-bex- adecenoate, and showed low levels of radiolabeled acetate incorporation into pheromone in gland culture. By the time of adult eclosion, the gland was fully competent. Precocious development of pheromone gland competency was induced by removing the head and thorax from pupae 2 days before adult eclosion. This effect appears to result from the reduction of ecdysteroid, since it was blocked by the administration of 20-hydroxyecdysone. This ability to manipulate the development of the pheromone gland was restricted to a critical period, since removal of head and thorax from younger pupae did not induce pheromone gland competency, and administration of 20-hydroxyecdysone to older pupae did not block its onset. In addition to differences in competency, early pharate and adult glands exhibited dissimilarities with respect to (1) the types of proteins synthesized in gland culture, and (2) the types of proteins translated from mRNA in vitro. Key WordIndex: Trichoplusia ni; cabbage looper moth; pheromone biosynthesis; functional development; gland culture; titer; mRNA; protein synthesis; 20-hydroxyccdysone INTRODUCTION Adult female moths produce and release sex phero- mones to attract conspecific males. Although many different compounds have been identified as phero- mones (Am et al., 1986), a number of studies have demonstrated fundamental similarities in the types of reactions used for pheromone biosynthesis (Bjostad et al., 1987). For example, de nero pheromone production often begins with fatty acid synthesis, followed by some variation of chain shortening and desaturation, and ends with the addition of a func- tional group via reduction/acetylation to form the acetate ester, or reduction/acetylation/oxidation to form the aldehyde. One of these enzymes, the All desaturase, has been shown to occur uniquely in moth pheromone glands, and belongs to a family of pheromone gland desaturases that act at carbon positions 11, 10 and 9 (Reelers and Wolf, 1988). Despite similarities in pathway reactions, the physiological cues that control pheromone pro- duction appear to vary with species. Juvenile hor- mone has been implicated (Cusson and McNeil, 1989) in controlling initiation of pheromone pro- duction in the true armyworm, Pseudaletia unipuncta, which is a migratory insect, but in the omnivorous leafroller moth, Platynota stultana, a juvenile her- *Author for correspondence. mone analog inhibited pheromone production (Web- ster and Card6, 1984). In some species, production of pheromone at specific times within the diel period is controlled by a peptide produced in the subeso- phageal ganglion that is released to turn on phero- mone production (Raina and Klun, 1984; Raina et al., 1987). In its absence, pheromone is not produced and the titer declines. This peptide, named PBAN (pheromone biosynthesis activating neuropeptide), has been identified and synthesized from the corn earworm, Heliothis zea (Raina et al., 1989), and the silkworm, Bombyx mori (Kitamura et al., 1989). In the redbanded leafroller moth, Argyrotaenia veluti- nana, pheromone is produced throughout the did period and requires the presence of.both a PBAN-like compound from the head (Tang et al., 1989) and a peptide factor from the bursa (Jurenka et al., 1991). Both factors must be present if full stimulation of the pheromone gland is to occur (Jurenka et al., 1991). In the cabbage looper moth, Trichoplusia ni, the major pheromone component, (Z)-7-dodecenyl acet- ate, is structurally related to the pheromones used by many other species and is biosynthesized by similar reactions (Bjostad et al., 1987; Morse and Meighen, 1987a). Unlike other moths, however, neither a PBAN-Iike compound nor other factors from the head appear to regulate the levels of pheromone, which seems to be continuously produced (Tang et al., 1989). The apparent lack of hormonal control m 2J/~,--^ 573