Localization of Motor Neurons and Central Pattern Generators for Motor Patterns Underlying Feeding Behavior in Drosophila Larvae

Motor systems can be functionally organized into effector organs (muscles and glands), the motor neurons, central pattern generators (CPG) and higher control centers of the brain. Using genetic and electrophysiological methods, we have begun to deconstruct the motor system driving Drosophila larval feeding behavior into its component parts. In this paper, we identify distinct clusters of motor neurons that execute head tilting, mouth hook movements, and pharyngeal pumping during larval feeding. This basic anatomical scaffold enabled the use of calcium-imaging to monitor the neural activity of motor neurons within the central nervous system (CNS) that drive food intake. Simultaneous nerve- and muscle-recordings demonstrate that the motor neurons innervate the cibarial dilator musculature (CDM) ipsi- and contra-laterally. By classical lesion experiments we localize a set of CPGs generating the neuronal pattern underlying feeding movements to the subesophageal zone (SEZ). Lesioning of higher brain centers decelerated all feeding-related motor patterns, whereas lesioning of ventral nerve cord (VNC) only affected the motor rhythm underlying pharyngeal pumping. These findings provide a basis for progressing upstream of the motor neurons to identify higher regulatory components of the feeding motor system.     

Neuroanatomy of the sucking pump of the moth, Manduca sexta (Sphingidae, Lepidoptera)

Knowledge of the neuroanatomy of the sucking pump of Manduca sexta (Sphingidae) is valuable for studies of olfactory learning, pattern generators, and postembryonic modification of motor circuitry. The pump comprises a cibarial valve, a buccal pump, and an esophageal sphincter valve. Cibarial opener and closer muscles control the cibarial valve. Six pairs of dilator muscles and a compressor muscle operate the buccal pump. The cibarial opener and one pair of buccal dilator muscles are innervated by paired neurons in the tritocerebrum, and the cibarial opener has double, bilateral innervation. Their tritocerebral innervation indicates that these muscles evolved from labro-clypeal muscles. The remaining paired buccal dilator muscles each are innervated by an unpaired motor neuron in the frontal ganglion. These motor neurons project bilaterally through the frontal connectives to dendritic arborizations in the tritocerebrum. These projections also have a series of dendritic-like arborizations in the connectives. The cibarial closer and buccal compressor muscles are also innervated by motor neurons in the frontal ganglion, but only the closer muscle neuron projects bilaterally to the tritocerebrum. The innervation of the pump muscles indicates that they are associated with the stomodaeum, and, therefore, the buccal pump evolved from the anterior stomodaeum rather than from the cibarium.     

Anatomy of the stomatogastric nervous system associated with the foregut in Drosophila melanogaster and Calliphora vicina third instar larvae

The stomatogastric nervous system (SNS) associated with the foregut was studied in 3rd instar larvae of Drosophila melanogaster and Calliphora vicina (blowfly). In both species, the foregut comprises pharynx, esophagus, and proventriculus. Only in Calliphora does the esophagus form a crop. The position of nerves and neurons was investigated with neuronal tracers in both species and GFP expression in Drosophila. The SNS is nearly identical in both species. Neurons are located in the proventricular and the hypocerebral ganglion (HCG), which are connected to each other by the proventricular nerve. Motor neurons for pharyngeal muscles are located in the brain not, as in other insect groups, in the frontal ganglion. The position of the frontal ganglion is taken by a nerve junction devoid of neurons. The junction is composed of four nerves: the frontal connectives that fuse with the antennal nerves (ANs), the frontal nerve innervating the cibarial dilator muscles and the recurrent nerve that innervates the esophagus and projects to the HCG. Differences in the SNS are restricted to a crop nerve only present in Calliphora and an esophageal ganglion that only exists in Drosophila. The ganglia of the dorsal organs give rise to the ANs, which project to the brain. The extensive conformity of the SNS of both species suggests functional parallels. Future electrophysiological studies of the motor circuits in the SNS of Drosophila will profit from parallel studies of the homologous but more accessible structures in Calliphora.     

The serotonin 5-HT7Dro receptor is expressed in the brain of Drosophila, and is essential for normal courtship and mating

The 5-HT(7) receptor remains one of the less well characterized serotonin receptors. Although it has been demonstrated to be involved in the regulation of mood, sleep, and circadian rhythms, as well as relaxation of vascular smooth muscles in mammals, the precise mechanisms underlying these functions remain largely unknown. The fruit fly, Drosophila melanogaster, is an attractive model organism to study neuropharmacological, molecular, and behavioral processes that are largely conserved with mammals. Drosophila express a homolog of the mammalian 5-HT(7) receptor, as well as homologs for the mammalian 5-HT(1A), and 5-HT(2), receptors. Each fly receptor couples to the same effector pathway as their mammalian counterpart and have been demonstrated to mediate similar behavioral responses. Here, we report on the expression and function of the 5-HT(7)Dro receptor in Drosophila. In the larval central nervous system, expression is detected postsynaptically in discreet cells and neuronal circuits. In the adult brain there is strong expression in all large-field R neurons that innervate the ellipsoid body, as well as in a small group of cells that cluster with the PDF-positive LNvs neurons that mediate circadian activity. Following both pharmacological and genetic approaches, we have found that 5-HT(7)Dro activity is essential for normal courtship and mating behaviors in the fly, where it appears to mediate levels of interest in both males and females. This is the first reported evidence of direct involvement of a particular serotonin receptor subtype in courtship and mating in the fly.     

FMRFamide-like immunoreactivity in the stomatogastric nervous system innervating the gut of the fly,Sarcophaga bullata

1. Distribution of FMRFamide-like peptide activity was examined in the stomatogastric nervous system of the adult fly, Sarcophaga bullata by the indirect immunofluorescent method.2. The neurons of the hypocerebral ganglion exhibit intense immunoreactivity and extend a thick axon bundle ventrally towards the proventriculus and crop.3. Near the mouth of the stomodeal valve a dense network of radial and circular immunoreactive processes branch off and innervate the proventriculus.4. Beyond the proventriculus, the crop duct and anterior midgut wall are also innervated by the FMRFamide-like immunoreactive processes of the nerve from the hypocerebral ganglion.5. From the pattern of innervation of the gut by FMRFamide-like immunoreactive processes it is suggested that this neuropeptide may regulate feeding activities in the adult fly.     

Anatomical and functional characterisation of the stomatogastric nervous system of blowfly (Calliphora vicina) larvae

The anatomy and functionality of the stomatogastric nervous system (SNS) of third-instar larvae of Calliphora vicina was characterised. As in other insects, the Calliphora SNS consists of several peripheral ganglia involved in foregut movement regulation. The frontal ganglion gives rise to the frontal nerve and is connected to the brain via the frontal connectives and antennal nerves (ANs). The recurrent nerve connects the frontal- to the hypocerebral ganglion from which the proventricular nerve runs to the proventricular ganglion. Foregut movements include rhythmic contractions of the cibarial dilator muscles (CDM), wavelike movements of crop and oesophagus and contractions of the proventriculus. Transections of SNS nerves indicate mostly myogenic crop and oesophagus movements and suggest modulatory function of the associated nerves. Neural activity in the ANs, correlating with postsynaptic potentials on the CDM, demonstrates a motor pathway from the brain to CDM. Crop volume is monitored by putative stretch receptors. The respective sensory pathway includes the recurrent nerve and the proventricular nerve. The dorsal organs (DOs) are directly connected to the SNS. Mechanical stimulation of the DOs evokes sensory activity in the AN. This suggests the DOs can provide sensory input for temporal coordination of feeding behaviour.     

atonal regulates neurite arborization but does not act as a proneural gene in the Drosophila brain

Drosophila atonal (ato) is the proneural gene of the chordotonal organs (CHOs) in the peripheral nervous system (PNS) and the larval and adult photoreceptor organs. Here, we show that ato is expressed at multiple stages during the development of a lineage of central brain neurons that innervate the optic lobes and are required for eclosion. A novel fate mapping approach shows that ato is expressed in the embryonic precursors of these neurons and that its expression is reactivated in third instar larvae (L3). In contrast to its function in the PNS, ato does not act as a proneural gene in the embryonic brain. Instead, ato performs a novel function, regulating arborization during larval and pupal development by interacting with Notch.     

5-HT2 receptors in Drosophila are expressed in the brain and modulate aspects of circadian behaviors

Dysregulation of 5-HT(2) receptor function has been strongly implicated in many neuropsychiatric disorders, including schizophrenia. At present, the molecular mechanisms linking 5-HT(2) receptor activation to behaviors is not well understood. In efforts to elucidate these processes, the fruit fly, Drosophila melanogaster, is proposed to serve as a powerful genetically tractable model organism to study 5-HT(2) receptor function. Data are presented here on the expression of the fly ortholog of the mammalian 5-HT(2) receptor, 5-HT(2)Dro, in the larval and adult brain of the fly, and on the involvement of these circuits in certain circadian behaviors. In the adult brain, 5-HT(2)Dro is expressed in the protocerebrum and ellipsoid body, areas believed to participate in higher order behaviors including learning, locomotion, and sensory perception. In the third instar larva, 5-HT(2)Dro receptor expression is detected in a specific pattern that markedly changes from early to late third instar. To probe the function of this receptor we have examined the effects of the 5-HT(2) receptor-specific agonist DOI in wild type and 5-HT(2)Dro hypomorphic flies on circadian behaviors. DOI was found to increase early day activity, eliminate anticipatory behavior, and reduce viability. The effects of DOI were significantly diminished in a 5-HT(2)Dro hypomorphic strain. Identifying the 5-HT(2)Dro receptor circuitry and behaviors they mediate are significant steps towards developing this model system to study conserved molecular mechanisms underlying behaviors mediated by 5-HT(2) receptors in mammalian systems.     

Neural inhibition of the corpus allatum in the last larval instar differs from that in adults in the blood-feeding insect, Rhodnius prolixus

An active corpus allatum (CA) in the blood feeding insect, Rhodnius prolixus, releases a substance that inhibits metamorphosis in larvae, and activates egg production in adults. In adults, transecting the nervus corporis cardiacum II's (NCCII), which are attached posteriorly to each protocerebral lobe, greatly increases egg production indicating that the adult CA is activated and receives neural inhibition from cells associated with the NCCII [Chiang, Arch. Insect. Biochem. Physiol. 39:126-131 (1998)]. In the present study, the NCCII's in fifth instar larvae were transected immediately before or after feeding to determine if these nerves normally inhibit CA activity in the last larval instar. Approximately 20 to 25 days following ingestion of a blood meal, L5's with transected NCCII's emerged as fully-formed adults with no larval characteristics. Examination of the brain in these recently emerged adults revealed that the NCCII's were absent. Since fifth instar larvae with transected NCCII's emerged with no juvenile characteristics, cutting the NCCII's did not activate the CA, indicating that the mechanism for inhibition of the CA differs in the last larval instar and adult animals.     

The role of the frontal ganglion in foregut movements of the moth,Manduca sexta

Two types of rhythmic foregut movements are described in fifth instar larvae of the moth, Manduca sexta. These consist of posteriorly-directed waves of peristalsis which move food toward the midgut, and synchronous constrictions of the esophageal region, which appear to retain food within the crop. We describe these movements and the muscles of the foregut that generate them.The firing patterns of a subset of these muscles, including a constrictor and dilator pair from both the esophageal and buccal regions of the foregut, are described for both types of foregut movement.The motor patterns for the foregut muscles require innervation by the frontal ganglion (FG), which lies anterior to the brain and contains about 35 neurons. Eliminating the ventral nerve cord, leaving the brain and FG intact, did not affect the muscle firing patterns in most cases. Eliminating both the brain and the ventral nerve cord, leaving only the FG to innervate the foregut, generally resulted in an increased period for both gut movements and muscle bursts. This manipulation also produced increases in burst durations for most muscles, and had variable effects on the phasing of muscle activity. Despite these changes, the foregut muscles still maintained a rhythmic firing pattern when innervated by the FG alone.Two nerves exit the FG to innervate the foregut musculature: the anteriorly-projecting frontal nerve, and the posteriorly-directed recurrent nerve. Cutting the frontal nerve immediately and irreversibly stopped all muscle activity in the buccal region, while cutting the recurrent nerve immediately stopped all muscle activity in the pharyngeal and esophageal regions. Recordings from the cut nerves leaving the FG showed that the ganglion was spontaneously active, with rhythmic activity continuing within the nerves. These observations indicate that all of the foregut muscle motoneurons are located within the FG, and the FG in isolation produces a rhythmic firing pattern in the motoneurons. We have identified several motoneurons within the FG, by cobalt backfills and/or simultaneous intracellular recordings and fills from putative motoneurons and their muscles.Abbreviations BC Buccal Constrictor - BC1 buccal constrictor motoneuron 1 - BC2 buccal constrictor motoneuron 2 - BD Buccal Dilator - BD1 buccal dilator motoneuron 1 - EC Esophageal Dilator - EC1 esophageal dilator motoneuron 1 - EC2 esophageal dilator motoneuron 2 - EC3 esophageal dilator motoneuron 3 - ejp excitatory junction potential - FG frontal ganglion - psp postsynaptic potential     

The brain can eat: Establishing the existence of a central pattern generator for feeding in third instar larvae of Drosophila virilis and Drosophila melanogaster

To establish the existence of a central pattern generator for feeding in the larval central nervous system of two Drosophila species, the gross anatomy of feeding related muscles and their innervation is described, the motor units of the muscles identified and rhythmic motor output recorded from the isolated CNS. The cibarial dilator muscles that mediate food ingestion are innervated by the frontal nerve. Their motor pathway projects from the brain through the antennal nerves, the frontal connectives and the frontal nerve junction. The mouth hook elevator and depressor system is innervated by side branches of the maxillary nerve. The motor units of the two muscle groups differ in amplitude: the elevator is always activated by a small unit, the depressor by a large one. The dorsal protractors span the cephalopharyngeal skeleton and the body wall hence mediating an extension of the CPS. These muscles are innervated by the prothoracic accessory nerve. Rhythmic motor output produced by the isolated central nervous system can simultaneously be recorded from all three nerves. The temporal pattern of the identified motor units resembles the sequence of muscle contractions deduced from natural feeding behavior and is therefore considered as fictive feeding. Phase diagrams show an almost identical fictive feeding pattern is in both species.     

The thoracic muscular system and its innervation in third instar Calliphora vicina Larvae. II. Projection patterns of the nerves associated with the pro‐ and mesothorax and the pharyngeal complex

We describe the anatomy of the nerves that project from the central nervous system (CNS) to the pro‐ and mesothoracic segments and the cephalopharyngeal skeleton (CPS) for third instar Calliphora larvae. Due to the complex branching pattern we introduce a nomenclature that labels side branches of first and second order. Two fine nerves that were not yet described are briefly introduced. One paired nerve projects to the ventral arms (VAs) of the CPS. The second, an unpaired nerve, projects to the ventral surface of the cibarial part of the esophagus (ES). Both nerves were tentatively labeled after the structures they innervate. The antennal nerve (AN) innervates the olfactory dorsal organ (DO). It contains motor pathways that project through the frontal connectives (FC) to the frontal nerve (FN) and innervate the cibarial dilator muscles (CDM) which mediate food ingestion. The maxillary nerve (MN) innervates the sensory terminal organ (TO), ventral organ (VO), and labial organ (LO) and comprises the motor pathways to the mouth hook (MH) elevator, MH depressor, and the labial retractor (LR) which opens the mouth cavity. An anastomosis of unknown function exists between the AN and MN. The prothoracic accessory nerve (PaN) innervates a dorsal protractor muscle of the CPS and sends side branches to the aorta and the bolwig organ (BO) (stemmata). In its further course, this nerve merges with the prothoracic nerve (PN). The architecture of the PN is extremely complex. It innervates a set of accessory pharyngeal muscles attached to the CPS and the body wall musculature of the prothorax. Several anastomoses exist between side branches of this nerve which were shown to contain motor pathways. The mesothoracic nerve (MeN) innervates a MH accessor and the longitudinal and transversal body wall muscles of the second segment. J. Morphol. 271:969–979, 2010. © 2010 Wiley‐Liss, Inc.     

Dopamine and serotonin in the larval CNS of a drosophilid fly, Chymomyza costata: are they involved in the regulation of diapause?

Developmental profiles of dopamine (DA) and serotonin (5-hydroxytryptamine, 5-HT) in the larval CNS of Chymomyza costata were measured by HPLC using electrochemical detection. Larvae of two strains, wild-type (W) and nondiapause mutant (M), were maintained either under long-day (LD, inducing pupariation) or short-day (SD, inducing diapause in W-strain) photoperiods. The levels of DA ranged from 10 fmol/CNS (early 3rd instar larvae) to 60 fmol/CNS (150-day-old diapausing larvae); the range for 5-HT was from 10 fmol/CNS to 75 fmol/CNS in the same larvae. During the 3rd larval instar, which is the decisive stage for photoperiodic induction of diapause, no differences were found in DA developmental profiles between different strains or conditions. Some differences were found in 5-HT developmental profiles, but only after the end of sensitive stage, and were therefore regarded as insignificant for regulation of developmental mode. Similarly, no clear correlations between the developmental profiles of DA and 5-HT and the course of developmental changes during the maintenance and termination of a few-month-long larval diapause were observed. Furthermore, the DA and 5-HT levels in the CNS were pharmacologically manipulated by feeding the larvae with either precursors or enzyme inhibitors of DA and 5-HT biosynthesis. Although retardations of growth and development were observed, the treated larvae retained full capacity for the photoperiodic response, irrespective of the level of DA or 5-HT in their CNS. Larvae with their 5-HT depleted to trace levels survived and were capable of diapause induction, maintenance, and termination. Depletion of DA to trace levels resulted in 100% mortality. Collectively, the present study indicates that 5-HT in the CNS is dispensable for the photoperiodic response in C. costata. More information is needed to elucidate the potential role of DA.     

Activation of the prothoracic gland by juvenile hormone and prothoracicotropic hormone in Mamestra brassicae

The effects of JHA (ZR-515) application or brain implantation on metamorphosis and adult development were examined in the last instar larvae and pupae of Mamestra brassicae. When JHA was applied to neck-ligated 4- or 5-day-old larvae or to the isolated abdomens of 5-day-old larvae containing implanted prothoracic glands taken from 5-day-old larvae, the insects pupated. Dauer pupae and diapausing pupae treated with JHA showed adult development. By contrast, pupation could not be induced by the application of JHA to 2- or 3-day-old neck-ligated larvae or to the isolated abdomens of 5-day-old larvae containing implanted prothoracic glands from 0-day-old larvae. Implantation of a brain into neck-ligated 3- or 5-day-old larvae (at the beginning of gut emptying and wandering) caused pupation of the host. A similar result was obtained when both a brain and the prothoracic glands from 0- or 5-day-old larvae were implanted into the isolated abdomens of 5-day-old larvae. These results indicate that activation of the prothoracic glands by application of JHA is temporally restricted to the last part of the last larval instar and to the pupal stage, while the activation by prothoracicotropic hormone (PTTH) can occur throughout the last larval instar and the pupal stage. In addition, the implantation of brains or application of JHA to neck-ligated 5-day-old larvae 25 days after ligation seldom induced pupation of the hosts, a result which suggests that larval prothoracic glands maintained under juvenile hormone (JH) or PTTH-free conditions for long periods of time may become insensitive to reactivation by both hormones.     

敲减神经肽F基因(npf)对亚洲玉米螟取食、生长发育和繁殖的影响

【目的】神经肽F(neuropeptide F, NPF)是无脊椎动物特有的一类神经肽,因其C末端是苯丙氨酸(F)而命名,参与昆虫的取食、生物节律、学习记忆等多种生理功能的调控。本研究旨在明确NPF对亚洲玉米螟Ostrinia furnacalis生长发育的影响,为害虫防治提供重要依据。【方法】采用一种基于工程菌高效合成靶向昆虫基因的dsRNA的方法经济有效地敲降npf,用低浓度(0.01%)和高浓度(0.02%)dsNPF和dsGFP(对照)分别饲喂亚洲玉米螟1龄初、3龄初和5龄初幼虫直至化蛹,检测5龄幼虫平均取食量、体重、体长、存活率和化蛹率,蛹羽化率和成虫产卵量,以及幼虫各龄期、蛹发育历期和成虫寿命。【结果】从亚洲玉米螟1, 3和5龄初幼虫开始饲喂0.01%和0.02% dsNPF时,与饲喂相应浓度dsGFP的对照相比,除个别点外,5龄幼虫的取食量、体重、体长、存活率和化蛹率,蛹羽化率和成虫单雌产卵量均显著降低,幼虫各龄期、蛹发育历期均显著延长,成虫寿命显著缩短。且dsNPF处理幼虫的龄期越早对发育的影响越大。其中0.01% dsNPF处理的1龄幼虫和0.02% dsNPF处理的3龄幼虫有90%的个体在蛹期死亡,而0.02%dsNPF处理的1龄幼虫有90%的个体在幼虫期死亡。【结论】结果提示NPF对亚洲玉米螟的发育和取食具有调控作用,这为探索新型绿色的害虫防治提供了依据。     

Metamorphosis of Wing Motor System in the Silk Moth, Bombyx mori: Origin of Wing Motor Neurons

The origin of the peripheral nerve and motor neurons that innervate the adult mesothoracic dorsal longitudinal muscles (DLMs) was examined in the silk moth, Bombyx mori . The anatomical features of the peripheral nerve and motor neurons were investigated by dissection, electron microscopy, and cobalt back-fill staining at different pupal stages. These studies showed that the peripheral nerve (IIN1c) that innervates the adult DLMs originates from a branch (db branch) of the larval mesothoracic dorsal nerve that innervates the larval DLMs. During metamorphosis the larval nerve shortens or lengthens locally without change in its basic branching pattern, and the db branch moves towards the mesothoracic ganglion to become the IIN1c. All the adult DLM motor neurons are from larval ones. Nine of the 14 larval DLM motor neurons survive during metamorphosis to become adult DLM motor neurons, and 5 disappear in early pupal stages.     

Leucokinin and callitachykinin immunoreactive neurons during postembryonic development of calliphora vomitoria (L.) (DIPTERA : CALLIPHORIDAE)

Neurons containing 2 types of myotropic neuropeptides were investigated by immunocytochemistry during postembryonic development of the brain and ventral nerve cord of the blowfly Calliphora vomitoria (Diptera : Calliphoridae). Antisera raised against the insect neuropeptides Callitachykinin II (CavTK II), Locustatachykinin I (LomTK I), and Leucokinin I (LK I) were used. Callitachykinin immunoreactive (CavTK–IR) neurons were detected from the 1st-instar larva throughout development to adult. The number of CavTK–IR cell bodies in the brain was 4–16 in larval stages, 10–84 in pupal stages, and over 140 neurons in the newly emerged fly. With the CavTK antiserum, the fibers of only 4 descending neurons were detected in thoracico–abdominal ganglia throughout development. The antiserum to LomTK displayed the same neurons as that to CavTK II as well as a small number of additional neurons. Notably, there were seen about 14–20 locustatachykinin-like immunoreactive (LomTK-LI) cell bodies in the thoracico–abdominal ganglia throughout development. Leucokinin-like immunoreactive (LK-LI) neurons were labeled throughout postembryonic development. In the brain, 2–4 LK-LI cell bodies were labeled from 1st-instar larva to 8-day-old pupa, and 6 LK-LI cell bodies were labeled in the adult brain. In the abdominal ganglia, 7 pairs of LK-LI cell bodies were labeled from 1st-instar larva to 96-h-old pupa, 8 pairs in 8-day-old pupa, and 9 pairs in newly emerged fly, respectively. The CavTK containing neurons in the brain displayed a drastic increase in numbers from larval stages to adult, which indicates an addition of functional roles for this type of peptide. During earlier pupal stages, the number of CavTK–IR neurons decreased. The LK-LI neurons, however, were strongly immunoreactive throughout postembryonic development. Only one additional pair of cells appeared in the brain and 2 additional pair of cells appeared in the abdominal ganglia of the adult as compared with larvae. The continuous high expression of LK-LI material may suggest a functional role for this type of peptide during development.     

Developmental Changes in Biogenic Amine Levels in the Central Nervous System and the Haemolymph of the Eastern Death's Head Hawk Moth,Acherontia styx (Lepidoptera: Sphingidae)

In an effort to understand the role of biogenic amines in insect development, changes in the levels of octopamine (OA), dopamine (DA), epinephrine (E), norepinephrine (NE), and serotonin (5-HT) in the brain, the optic lobes and the haemolymph of different developmental stages of Acherontia styx were analyzed using HPLC with electrochemical detector. In the brain, OA was the most abundant monoamine. DA, OA, and E levels in larvae peaked around the wandering stage (W). A dramatic increase in DA, 5-HT, and E levels was observed in the brain of the adult as compared to the pupal stage. NE, however, was not detected in the brain of most stages of the insect, except in the brain of 20-day-old pupae and adults. A 3-fold increase in OA levels was observed in the optic lobes of the adult as compared to late pupal stage. No changes were observed for E, DA, and 5-HT. NE was not detected in the optic lobes. In the haemolymph of 5^th instar larvae, OA was also the most abundant amine. Both DA and OA peaked prior to the onset of the W stage. In contrast, E and NE concentrations decreased with development of the 5^th instar larvae. 5-HT was not detected in the haemolymph. Finally, different profiles for amine levels were observed for the two forms of the 5^th instar larvae (green vs brown). These results are interpreted in the light of the role of biogenic amines and their relation to development in the nervous system of lepidopteran insects.