Hugo Schooneveld

Wageningen University & Research | WUR · Department of Entomology

Electromagnetically sensitized people may develop symptoms and health problems when exposed to certain types of electromagnetic fields (EMF), known as electrical hypersensitivity (EHS). Over time, the effects may become stronger if such exposure continues. The Dutch EHS Foundation is committed to finding ways to understand these phenomena and to do...

Three insect growth regulators (IGRs) were tested on the summer fruit tortrix moth Adoxophyes oratio in laboratory and small-scale field experiments. In the laboratory, the amounts of IGRs required to induce a defined morphogenetic effect on pupation were determined. For the juvenoids Ro 10–3108, Ro 10–6976, and Ro 10–9168 the doses were 0.03 μg, 0...

Our interest in the male accessory glands (MAGs) of Leptinotarsa decemlineata was raised recently by our finding that certain cells produce a secretory substance that is recognized by one of our monoclonal antibodies (MAC-18), developed for the immunohistochemical demonstration of peptidergic neurons in the brain. We undertook to isolate this subst...

Immunohistochemical studies showed that the alimentary canal of Leptinotarsa decemlineata receives serotoninergic innervation from different neurons in the central and stomatogastric nervous system. The foregut is innervated by the frontal ganglion. Four of the 6–8 large neurons present in this ganglion have axons which run to the musculature of th...

We analyzed the anatomy of two diffuse neurohemal systems for serotonin in the head of the Colorado potato beetle Leptinotarsa decemlineata by means of immunohistochemistry. One system is formed by axons from two bilateral pairs of neurons in the frontal margin of the suboesophageal ganglion that enter the ipsilateral mandibular nerve, emerge from...

The distribution of—still chemically undefined—peptide epitopes in subclasses of peptidergic neurons in the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera : Chrysomelidae) was studied in preparation for peptide isolation by immunological methods. Two monoclonal antibodies, MAC-13 and MAC-3, were selected for their capacity to reveal...

The male Colorado potato beetle, Leptinotarsa decemlineata (Say) has one pair of elongate accessory glands. Using a monoclonal antibody, specific for the lateral neurosecretory cells in the brain, a small percentage of the epithelial cells is strongly immunolabelled. The antibody associates with secretory granules which are abundant in these cells....

In an immunohistochemical study of the ventral nerve cord of L. decemlineata, five distinct neuron categories were distinguished: 1) Two paired segmental twin interneurons occur in each ganglion or neuromere; their axons distribute processes over almost the entire nerve cord and run to the cerebral ganglion complex. In contrast, other axons are dis...

In this paper a new technique for microwave-accelerated tissue fixation and washing is described. The temperature of the irradiated specimens is controlled by means of a specially designed water-cooling device. Two types of fixation fluids, one of them containing rather concentrated picric acid, and a washing procedure were tested empirically on di...

Monoclonal antibodies were developed against peptidergic neurons in the nervous and endocrine tissues of the Colorado potato beetle by the immunization of mice with unpurified homogenates of these tissues. Methods were optimized to enhance chances for successful antibody production and selection, such as the pretreatment of the beetles, preparation...

Immunization of mice with crude or purified homogenates of brain and endocrine organs of the Colorado potato beetle, Leptinotarsa decemlineata (Say), generated antibodies against specific antigens in the insect tissue. Hybridomas were prepared and screened immunocytochemically for the production of monoclonal antibodies (MAB) that recognized specif...

Recently, immunocytochemical (ICC) techniques have enjoyed increasing popularity for the rapid and convenient qualitative detection of antigens (Ags) in tissues and cells. The techniques are basically rather simple. As most of the necessary reagents are commercially available, every laboratory is now able to carry out standard ICC experiments, prov...

Immunocytochemical reactions with region-specific antibodies to adipokinetic hormone were used to study the stainability and structural organization of the intrinsic glandular cells of the corpora cardiaca of 19 insect species belonging to 10 orders. There was considerable variation in the nature of the glandular product as well as in morphology of...

The immunocytochemical reactivity of the glandular cells of the corpus cardiacum (CCG-cells) of Locusta migratoria and Schistocerca gregaria was investigated at the electron-microscopic level, using the protein A-gold method, with three antisera against fragments of the adipokinetic hormones AKH I and AKH II. This combination of antisera permitted...

The occurrence of adipokinetic hormone (AKH) and red pigment concentrating hormone (RPCH)-like neuropeptides in the central nervous system of different invertebrate species other than insects was investigated immunocytochemically with polyclonal antisera to N- and C-terminal regions of the AKH molecule. Substances reacting with the C-terminal speci...

Using antisera produced against different parts of the insect adipokinetic hormone (AKH), it was possible to detect adipokinetic hormone-reactive peptides in the eyestalk of the prawn Palaemon serratus. Immunopositive staining was obtained in some neurosecretory cells of the medulla externa X organ (MEX), of the medulla terminalis X organ 2 (MTGX-2...

A large number of antisera mainly raised against mammalian hormones are tested immunocytochemically on the GEP-endocrine system of mouse and fish (Barbus conchonius). The endocrine pancreas of mouse and fish appeared to contain the same four endocrine cell types; insulin-, glucagon-, PP- and somatostatin-immunoreactive cells. In mouse about 13 GEP...

An immunocytochemical method was used to differentiate between immunoreactive substances in glandular cells in the corpora cardiaca (CC) and in certain cerebral neurons in 2 insect species, Locusta migratoria migratorioides and Periplaneta americana. The staining properties of antisera raised to different parts of the decapeptide adipokinetic hormo...

It is becoming clear that adipokinetic hormone (AKH) is only one representative of a rapidly expanding family of neuropeptides extracted from different insect species. A similar peptide, the red-pigment concentrating hormone (RPCH), has been isolated from shrimps and the question arises whether these AKH/RPCH-related peptides are evolutionary relat...

Evidence is presented that neurons in the adult Colorado potato beetle contain a proctolin-like substance. By use of immunocytochemical methods the location of immunoreactive neurons in the central and stomatogastric nervous systems is described. No such neurons were found in the proto- and deutocerebrum or optic lobe. Few immunoreactive neurons ar...

The distribution of intrinsic glandular cells containing adipokinetic hormone (AKH)-like material in the corpora cardiaca (CC) and the occurrence of immunoreactive neurons in the nervous system in 19 species belonging to nine insect orders was studied by means of an immunocytochemical method (peroxidase-antiperoxidase), with antisera raised against...

A large number of antisera to regulatory vertebrate peptides was tested immunocytochemically on the nervous system of the Colorado potato beetle to further characterize the peptidergic cells of the neuro-endocrine system and to reveal cells participating in endocrine control mechanisms. Neurons, neurosecretory cells, axons and axon terminals were r...

The application of horseradish peroxidase for tracing the cells innervating the corpus allatum in adult Leptinotarsa decemlineata, using simple instruments, is described. The corpus allatum in this insect appears to be innervated by a single group of about eight cells. The size and position of these cells indicate that they belong to the L-type lat...

Antisera against vasopressin, vasotocin, oxytocin, neurophysin-1 and neurophysin-2 were used to investigate immunocytochemically the presence of neurons containing substances antigenically related to these peptides in the nervous system of the Colorado potato beetle. Ten different antisera were used, four against vasopressin, three against oxytocin...

Particular neurons in the nervous system of the Colorado potato beetle, Leptinotarsa decemlineata, are recognized by antisera against bovine pancreatic polypeptide and FMRFamide. Both antisera react with the same neurons. Solid phase absorptions showed that antiserum against bovine pancreatic polypeptide cross-reacts with FMRFamide, whereas antiser...

An antiserum was raised against tyrosine-adipokinetic hormone ([Tyr1]-AKH). In immunohistochemical procedures, it revealed the AKH cells in the glandular lobes of the corpora cardiaca (CC) of Locusta migratoria with high specificity. In addition, an immunologically related peptide was detected in certain neurons of the central nervous system which...

The in vivo control of corpus allatum (CA) activity in females of Leptinotarsa decemlineata was investigated. Evidence was obtained that CA activity is adjusted by negative feedback when juvenile hormone (JH) titres are changed experimentally. Conclusions are based on determination of the rate of in vitro JH synthesis by the CA, on changes in CA vo...

Light and electron microscopic studies, including the use of the vital dyes trypan blue and acridine orange, indicate that the topical application of precocene II rapidly triggers degenerative processes in the corpora allata (CA) leading within a few days to the virtual disappearance of the parenchymal cells of these glands. The following sequence...

Precocene II causes an irreversible regression of corpora allata in young 4th instar nymphs of the migratory locust. Within 2 h after application, the cells collapse. Cell fragments are subsequently phagocytosed by haemocytes.

Topical applications of Cecropia juvenile hormone I (JH) and several analogues, 1 day after the initiation of diapause, induce a break in diapause 8 to 10 days later, characterized by emergence from the soil, feeding, mating, and reproduction. Activation is only temporary when beetles are kept in short-day photoperiods. The percentage of beetles ac...

Topical application of insect growth regulators (IGRs) on older L3 last stage larvae of Adoxophyes orana (Fischler von Rosenstamm) eventually inhibited adult ecdysis. Applications on young L3 larvae only gave this effect when pupae retained juvenile characters scored 4 or higher on a 7-point scale. Reproductive activities of moths emerging from pup...

The degree of juvenilization of pupae of Adoxophyes orana (Fischler von Rosenstamm), brought about by 2 insect growth regulators, isomer mixtures of methyl 10,11-epoxy-7-ethyl-3,11-dimethyl-2,6-tridecadienoate (JH) and 6,7-epoxy-3,7-dimethyl-1-[3,4-(methylenedioxy)phenoxy]-2-nonene (JHA), was largely dependent on the rearing temperature at which th...

The ultrastructure of seven types of neurosecretory cells (NSC) in the medial and lateral groups of the protocerebrum is described. The differences among cell types established earlier by light microscopy parallel differences in size and appearance of the neurosecretory particles observed in electron micrographs. No relationship was found between t...

The pathways of axonal transport of secretions from neurosecretory cells (NSC) in the medial group (viz. A-, A1, B-, and C-type NSC) and the lateral group (L-type NSC) are described. Individual axons can be recognized in the electron microscope by the kind of neurosecretory particles they contain. In general, the secretions from the medial NSC are...

In Colorado beetle females fed with physiologically aged potato leaves, an inhibition or even a standstill of reproduction occurs, followed by diapause. In such beetles, the volume of the corpora allata is reduced and the medial cerebral neurosecretory cells do not transport their neurosecretory material. In feeding tests, it is shown that the beet...

In this paper the gross anatomy of the neurosecretory system and the structure of neurosecretory cells (NSC), corpora cardiaca (CC), and corpora allata (CA) of the female Colorado beetle has been described in detail, and an analysis of the patterns of secretory activity throughout adult life and under short-day and long-day breeding conditions has...