The presence of ecdysteroids during the larval life cycle and in the abdomens and ovaries of pregnant tsetse flies was established using radioimmunoassay. The hormone titre rises on day 9 of the larval life cycle 2–3 days after the hardening of the polypneustic lobes, mouthparts, phragma and anus. How initiation of tanning of the cuticle of the polypneustic lobes and later the puparium of tsetse fly is regulated is discussed as these events are separated in time by several days. It would seem to be unlikely that the pyrokinin neuropeptide, which is responsible for initiating the events that lead up to pupariation, is also involved 2–3 days earlier in the life cycle. The objective was to ascertain whether 14C-l-p-tyrosine enters the lobe cuticle in vivo and in vitro much faster than into integument cuticle on the 7th day of the pregnancy cycle. The result showed that the uptake of tyrosine into the lobes was 11–12 times faster than into the rest of the cuticle. Some evidence is presented that haemocytes underlying the epidermis are involved in overcoming the barrier to uptake of the phenolic compounds required for sclerotization of the lobes. Pupariation could be retarded by physical means such as ligaturing of the larvae. To try to break this inhibition (retardation) of pupariation in ligatured larvae, 14C-l-p-tyrosine metabolites were injected, with and without ecdysteroids, into the anterior of ligated larvae. The result of this experiment showed that the steroid hormone did not overcome the inhibition but neither does injecting tyrosine, dihydroxyphenylalanine, dopamine or tyramine. Evidence obtained from chromatography and electrophoresis indicated that N-acetylation of dopamine did not occur in the haemolymph of larvae that were artificially retarded. This impact raises the possibility that N-acetyltransferase and acetyl-coenzyme A could be released in pre-pupae after the action of a neuropeptide breaks the retardation of tanning.

Total ecdysteroid-like immunoreactive material was assayed and quantified in adults of the parasitic nematode N. brasiliensis during the intestinal phase in the rat in order to detect possible physiological fluctuations in titre. Worms of the same sex isolated from one rat were pooled in order to quantify ecdysteroids using enzyme immunoassay (EIA). The concentration of ecdysteroids fluctuated during adult life according to the sex and the age of the parasite. Important differences of levels of ecdysteroid-like compounds between the two sexes of parasites were noted particularly at 128 and 168 h post-infection. The peak at 128 h, present in female, but not in male worms, corresponds to the time of egg-laying. Following HPLC-EIA analysis, the presence of ecdysone, 20-hydroxyecdysone and apolar ecdysteroid-like material was ascertained during this peak. The physiological role and the possible origin of ecdysteroids in this nematode are discussed.

The effects of the insect hormones, ecdysone and 20-hydroxyecdysone, certain non-steroidal ecdysteroid agonists (RH compounds) and the inhibitor, azadirachtin, on the timing of the 3rd-stage moult of Dirofilaria immitis were investigated. 20-Hydroxyecdysone and RH 5849 when used at a concentration of 10−5 M, resulted in a premature timing of this moult. Azadiracthin, at a similar concentration, prevented moulting of most of the larvae to the 4th stage. The results are discussed in relation to the possibility of a hormonal role for ecdysteroids and neuropeptide-like compounds in the control of ecdysis in filarial nematodes, that maybe somewhat comparable to the system which is found in insects.

Ecdysteroids (moulting hormones), juvenoids and neuropeptides in ticks are reviewed but, by far, the emphasis is on the former since this class of hormones has been the subject of most investigations. In immature stages of ticks, ecdysteroids have been shown to regulate moulting and to terminate larval diapause. Although there is a paucity of information on the molecular action of ecdysteroids in ticks, their action appears to be via a heterodimeric ecdysone/ultraspiracle receptor, as in insects. The role of ecdysteroids in sperm maturation in adult males is considered. In females, ecdysteroids function in the regulation of salivary glands, of production of sex pheromones and of oogenesis and oviposition. There is evidence for ecdysteroid production in the integument and pathways of hormone inactivation are similar to those in insects. Ecdysteroids also function in embryogenesis. Although evidence for the occurrence and functioning of juvenile hormones in ticks has been contradictory, in recent thorough work it has not been possible to detect known juvenile hormones in ticks, nor to demonstrate effects of extracts on insects. Factors (neuropeptides) from the synganglion affect physiological processes and limited immunocytochemical studies are reviewed. Sigificantly, a G-protein-coupled receptor has been cloned, expressed, and specifically responds to myokinins.

Despite the growing acceptance and adoption of the IPM concept, up until now no “optimal” or pragmatic IPM programme has been realized. This is apparently because most of these programmes are still in need of new types of pesticides, with no or negligible adverse impact on the environment including the non-target beneficial arthropods. From a practical perspective, such pesticides are still rather far reaching. Most, if not all, pesticides in current use as components of IPM programmes are so far belonging, in one way or another, to the conventional pesticides. It is admitted that in designing IPM programmes, several efforts should be made to minimize not only the frequency of pesticide applications but also their negative consequences on beneficial arthropods. Whilst the first goal has been achieved in several situations, the other one appeared hardly accessible. A number of methodologies are currently being suggested to cause conventional pesticides more selective, but apart from having many technical and other constraints, they might at best have fallen short of providing the hopeful solution. These together with other problems facing the development and practical utilization of juvenoids and related compounds are discussed mainly in view of their possible contribution to tropical pest management.

Female ticks of Ornithodoros porcinus porcinus undergo a series of adult moults when fed on blood containing ecdysteroids. The supermoulted ticks are bigger, ingest larger blood meals and lay more eggs than normal females. However, their rate of conversion of blood into eggs and their oxygen uptake are reduced in comparison to normal ticks. Their ability to resorb the rehydrated salt crystals is impaired. They are unable to shed the cuticle of the Géne's organ area leaving the organ constantly protruding, thus making the ticks vulnerable to dehydration. These factors are probably responsible for the very high mortality and the failure of most of the ticks to moult at the third supermoulting cycle.