Thomas R. Odhiambo

The architecture of the accessory reproductive glands of the male desert locust: 1: Types of glands and their secretions

The accessory reproductive glands of the male desert locust were studied by histological, histochemical, and phase-contrast techniques. It was found that the characteristics of the glandular epithelium and their corresponding secretions permit the division of the accessory glands into nine distinct types. Three types produce coarsely granular mucopolysaccharide secretions (glands 1, 11, and 12); three types produce finely fibrous mucopolysaccharide secretions (glands 2, 4, and 7-10, 13-15); one type produces a globular mucopolysaccharide or mucoproteinaceous secretion (gland 6); one type produces an acidic lipoprotein complex (glands 3 and 5); and one is the functional seminal vesicle (gland 16). Consequently, the various secretions are separated as a result of a vertical segregatign of the various cell types that are responsible for glandular activity.

Gonadal lesions in virus-infected male and female tsetse, Glossina pallidipes (Diptera: Glossinidae).

Abstract Ovaries and testes, dissected out and collected from wild Glossina pallidipes with virus-infected, hypertrophied salivary glands, were processed for routine electron microscopy and examined for pathological changes. Lesions in the male gonads were more severe than in their female counterpart and involved both testes in every case. Examination of the ovaries of the virus-infected females with hypertrophied salivary glands showed that although the occasional germarium appeared normal, the majority were affected by degeneration and severe necrosis. The degenerate ovarioles also showed virus particles within germarial cells. Sections of testicular follicles of adult males with hypertrophied salivary glands revealed a total arrest of spermatogenesis, depicted by complete absence of meiotic and postmeiotic stages. The follicles contained only sheets of undifferentiated premeiotic spermatogenic cells, i.e., spermatogonia and primary spermatocytes. In some testes, degeneration (characterized by diffuse vacuolation and exfoliation of degenerate cells leading to empty lumina) was superimposed on lack of sperm development. Testes of normal adult male G. pallidipes , on the other hand, showed swarms of entangled spermatozoa. The demonstration of virus particles within the germarium of the ovariole of females with hypertrophied salivary glands and the complete sterility observed in males with hypertrophied salivary glands identify the virus of G. pallidipes as a potential candidate for the biological control of the species.

The architecture of the accessory reproductive glands of the male desert locust. 5: ultrastructure during maturation

The accessory reproductive glands of the male desert locust were studied with the electron microscope from the time of adult emergence until full sexual maturity was attained (10 days). Observations on the changes in the nucleus and the cytoplasm of the glandular epithelium, particularly those organelles involved in the elaboration of cell secretions, were made during the maturation of the accessory glands. Cells of gland 16 (the functional seminal vesicle) exhibit numerous ribosomal aggregates, have a concentration of mitochondria along their luminal surface, and show some secretory activity, even at the time of adult emergence. On the other hand, all other accessory glands show very little development of the secretory apparatus (rough-surfaced endoplasmic reticulum, polyribosomes, Golgi elements, elaborate mitochondria, etc.) until after the fifth adult day. These changes parallel changes in the secretory activity of the adult corpus allatum; and it is suggested that the corpus allatum hormone regulates the maturation of the truly glandular accessory glands of the locust, but not that of the functional vesicle.

Immunization of cattle with a semi-purified fraction of solubilized membrane-bound antigens extracted from the midgut of the tickRhipicephalus appendiculatus

Boran cattle were immunized with a semi-purified fraction (F2) of solubilized membrane-bound antigens extracted from the midgut of the tickRhipicephalus appendiculatus. A subsequent challenge with all stages ofR. appendiculatus showed protection of the cattle to a significant degree. There was a decrease in engorgement weight of ticks, the number which fed above critical engorgement weight was considerably reduced, and about 38% of the larvae which fed to repletion did not moult. The major cause of death of adult female ticks was the increased grooming by cattle as a result of increased dermal irritation.

The Architecture of the Accessory Reproductive Glands of the Male Desert Locust: III. Components of the Muscular wall

An electron microscopic study of the sheath enclosing the accessory reproductive glands of the male desert locust has shown that it consists, for the most part, of a single myofibril, and that other tissues (nerve fibres, tracheal elements, and the fat body) are also associated with it to a greater or lesser extent. The myofibril has special features associated with the Z-bands, including the regular infolding and the attachment of the sarcolemma at the Z-bands, and the synapsing of nerve axons at these infoldings, which perhaps facilitate the rapid transmission of nerve impulses into the myofibril. The distribution of the T-systems and sarcoplasmic reticulum (SR) is described, and their relationship to the speed of action of the myofibril is discussed. The myofibril exhibits three distinct bands: the A-, I-, and Z-bands. In the A-band, each thick myofilament is surrounded by 10 to 12 thin filaments. This finding is related to similar findings in other arthropod visceral and slow-acting skeletal muscles. The basement membrane surrounding the glandular epithelium comprises two parts: the inner part, which is structureless and contains neutral mucopolysaccharide; and the outer part which contains numerous collagen-like fibrils and stains for acid mucopolysaccharide. This characteristic is considered in relation to the insertion and function of the myofibril.

The architecture of the accessory reproductive glands of the male desert locust 2: Microtubular structures.

Cytoplasmic microtubules are distributed widely in the mature accessory reproductive glands of the male desert locust. They are not concentrated in any particular region of the cytoplasm, but they appear to be closely associated with mitochondria and the Golgi apparatus. The individual microtubules have a helical configuration, and they are often congregated in bundles. It is suggested that the microtubules arise from Golgi regions, and that they function as a scaffolding for the maintenance of the shape of the glandular cells.

Studies on infection rates of human-baited anthropophilic sandflies in Machakos District, Kenya

Investigation of sandfly vectors of visceral leishmaniasis (kala-azar) was intensified after the epidemic outbreak of the latter in Machakos District, Kenya, in the early 1970s. Studies were carried out to assess the infection rate of potential vectors using human baits during the height of the 1978 epidemic outbreak. The results presented here indicated that, in Machakos District, sandflies captured when coming to human baits had higher infection rates than those collected in the natural resting sites using suction tubes.

Spermatophore of the tsetse, Glossina morsitans morsitans Westwood: an ultrastructural study.

Sperm are transferred from male to female tsetse, as in most insect species, within a spermato-phore. The spermatophore of the tsetse species, Glossina morsitans morsitans Westwood (Diptera: Glossi-nidae), is highly organized, and can be visualized as a sac deposited in the uterus of the female tsetse. The wall of the spermatophore comprises two layers, whose components are strikingly similar to those of the secretions made by the male accessory reproductive glands. Dense aggregates of material, matrix filaments, and clusters of granules predominate in both. An ultrastructural study of these components is reported in this paper.

The composition of the salivary gland secretion of the tsetse, Glossina morsitans morsitans Westwood 1850 (Diptera: Glossinidae).

Polyacrylamide gel disc electrophoresis of the salivary secretion from the tsetse, Glossina morsitans morsitans Westwood, showed 11 protein bands, four of which were characterized as glycoproteins. Sixteen amino acids and four sugars in the hydrolysates of saliva were identified. Thin layer chromatography showed five lipid classes and three phospholipids. The secretion is a clear, transparent, viscous fluid with a pH between 7.00 and 7.5. These findings are discussed in relation to the nutritional requirements of the metacyclic forms of trypanosomes that may be found in the salivary glands.

International aspects of crop protection: the needs of tropical developing countries

The special circumstances of plant protection in tropical developing countries, particularly in Africa, are considered within the context of the needs of the preponderant rural farming community, and in respect of food production. The problems are exacerbated by the existence of complex cropping systems (intercropping), the abundance and diversity of pests, the meagre knowledge of the plant-host-pest relationships, and the poor availability of the scientific understanding of the components of pest control and inputs essential for integrated pest management. Institutional innovations, including stepped-up professional training of experts in the field of plant protection, are required to usher in a more sustained effort in efficacious plant protection in these regions. Attempts in this direction are briefly discussed.