The gene encoding juvenile hormone response (Krüppel homolog1, Kr-hl) in Coccinella septempunctata was investigated by cloning and analysing expression profiles in different developmental stages and tissues by quantitative real-time polymerase chain reaction (PCR). C. septempunctata Kr-hl (CsKr-hl) encoded a 1338 bp open reading frame (ORF) with a predicted protein product of 445 amino acids; the latter showed high similarity to orthologs in other species and contained eight highly-conserved Zn-finger motifs for DNA-binding. CsKr-hl was expressed in different developmental stages of C. septempunctata. The expression levels of CsKr-hl in eggs, 2nd, 3rd, 4th instar larvae, and pupa were 3.31, 2.30, 7.09, 0.58, and 7.48 times the number of 1st instar larvae, respectively. CsKr-hl expression levels in female adults gradually increased at 25–30 days and were significantly higher than expression at 1–20 days. CsKr-hl expression in 20–30 days-old male adults was significantly higher than males aged 1–15 days. CsKr-hl expression levels in heads of male and female adults were significantly higher than expression levels in the thorax, adipose, and reproductive system. Interestingly, CsKr-hl expression levels in the adipose and reproductive system of female adults were significantly higher than in adult male corresponding organs, which suggest that CsKr-hl plays an important role in regulating reproductive development in C. septempunctata.

Sexual maturation of Anastrepha fraterculus is a long process. Methoprene (a mimic of juvenile hormone) considerably reduces the time for sexual maturation in males. However, in other Anastrepha species, this effect depends on protein intake at the adult stage. Here, we evaluated the mating competitiveness of sterile laboratory males and females that were treated with methoprene (either the pupal or adult stage) and were kept under different regimes of adult food, which varied in the protein source and the sugar:protein ratio. Experiments were carried out under semi-natural conditions, where laboratory flies competed over copulations with sexually mature wild flies. Sterile, methoprene-treated males that reached sexual maturity earlier (six days old), displayed the same lekking behaviour, attractiveness to females and mating competitiveness as mature wild males. This effect depended on protein intake. Diets containing sugar and hydrolyzed yeast allowed sterile males to compete with wild males (even at a low concentration of protein), while brewer´s yeast failed to do so even at a higher concentration. Sugar only fed males were unable to achieve significant numbers of copulations. Methoprene did not increase the readiness to mate of six-day-old sterile females. Long pre-copulatory periods create an additional cost to the management of fruit fly pests through the sterile insect technique (SIT). Our findings suggest that methoprene treatment will increase SIT effectiveness against A. fraterculus when coupled with a diet fortified with protein. Additionally, methoprene acts as a physiological sexing method, allowing the release of mature males and immature females and hence increasing SIT efficiency.

The secretions of the two colleterial glands give rise to the walls of the ootheca which, when hardened, serve to protect fertilised eggs in the cockroach P. americana. The larger left gland (LCG) secretes a β-D-glucoside of 3,4-dihydroxybenzoate, several proteins (oothecins), calcium oxalate crystals and a latent phenoloxidase enzyme. The smaller right gland (RCG) secretes a β-glucosidase. When the two secretions mix in the genital vestibulum, the glucoside is hydrolyzed to glucose and free dihydroxybenzoate, which is then oxidized by the phenoloxidase to the o-benzoquinone, which cross-links the oothecins Scanning and thin section electron microscopy (EM) showed haemocytes adhering to the LCG. The haemocytes were obtained by washing the gland with insect saline; and, when they were incubated with labelled tyrosine, they showed an enhanced ability to decarboxylate L-p-tyrosine to tyramine and then deaminate and oxidize tyramine to give p-hydroxyphenylacetate. After removal of adhering haemocytes, the LCG was no longer able to decarboxylate tyrosine. Injection of α-ecdysone into the abdomens of recently emerged adult females inhibited synthesis of a phenolic glucoside in the developing LCG but not of β-glucosidase produced by RCG. Furthermore, injecting inhibitors of the decarboxylase and monoamineoxidase enzymes partly closed down synthesis in vivo of the phenolic glucoside by LCG. Therefore, in the adult female cockroach, tyramine was converted to p-hydroxyphenylacetate in the haemocytes and then transferred to the gland where it was hydroxylated to 3,4-dihydroxyphenylacetate, which gave rise to a dihydroxybenzoate. Evidence suggested that biosynthesis of the oothecal sclerotizing agent could be controlled by juvenile hormone (JH) acting on the LCG or on haemocytes adhering to the gland.

Aspects of vitellogenesis, known to be controlled by juvenile hormone, are adversely affected by Hymenolepis diminuta infection of Tenebrio molitor, in spite of circulating titres of the hormone remaining unchanged. It has therefore been proposed that juvenile hormone binding is disrupted at the tissue site level. Juvenile hormone III binding sites were located in the nuclear, microsomal and post-microsomal supernatant fractions of the follicle cells of Tenebrio molitor. When JH-III binding was quantified for both control and Hymenolepis diminuta-infected beetles, binding in the nucleus and cytosol were found to be largely unaffected. However, microsomal binding was severely disrupted; on days 3 and 6 post-infection, binding was greatly diminished, on day 9 post-infection, binding was slightly reduced and, by day 15, binding was ‘restored’ to that of control insects. Using follicle cell microsomes at day 3 post-infection, previous Scatchard analysis revealed the presence of at least two JH-III binding sites. The first is of higher affinity, Kd = 5·3 x 10·5 x 10−11 mol/mg protein and the second of lower affinity Kd = 7·7 x 10−7 M, Bmax = 9·75 x 10−11 mol/mg protein. A comparison with microsomal binding parameters of follicle cells from non-infected Tenebrio indicated that although the Bmax values were unchanged, the Kd value of the higher affinity site was increased by approximately 5-fold. These data are indicative of a parasite-induced competitive binding inhibitor.

Infection with developing metacestodes of the rat tapeworm, Hymenolepis diminuta, is known to retard the accumulation of the yolk protein, vitellin, in the terminal ovarian follicles of the intermediate host, Tenebrio molitor. It is probable that this is the result of competitive inhibition of juvenile hormone binding at a microsomal binding site in the beetle follicular epithelium. Experiments were designed to test the hypothesis that inhibitor molecules were circulating in the haemolymph of infected beetles. Whole haemolymph, collected from male or female beetles at various stages post-infection, was injected into non-infected female recipients 2 days post-emergence. Ovaries were removed 3 days later and the vitellin content of the same sized follicles measured using an ELISA. The vitellin content of follicles from recipients of haemolymph from females infected with metacestodes at stage 1 and stage 3–4 was significantly reduced (24 and 27·9%) compared to sham-infected females. However, haemolymph from females infected with mature metacestodes did not affect the vitellin content. Results were thus comparable to those obtained by monitoring ovarian vitellin levels in female T. molitor with bona fide infections. Haemolymph from infected males did not affect ovarian vitellin content. These results indicate that molecules that can modulate vitellogenesis may be present in the haemolymph of females infected with developing metacestodes but that these factors disappear later in infection.

The use of synthetic acaricides in tick control is increasingly becoming more expensive. As a result, a lot of Africa's resource-poor farmers are failing to dip their cattle regularly. Natural products offer these farmers a cheaper alternative to synthetic acaricides. There is indeed a great potential for the use of Africa's huge natural resources, the plants to develop sources of acaricides to reduce the cost of tick control being locally available and potentially being able to be produced and used by farmers themselves or by cottage industries. It is, however, necessary that research centres such as ICIPE encourage the development of systematic research on natural products in order to bring about the Tephrosia vogelii leaf extracts observed to be highly toxic to one-, two- and three-host ticks and cattle sprayed with the extract had a residual protection period of 10 days from re-infestation by ticks.

Three aromatic juvenoids were evaluated for morphogenetic activity on Schistocerca americana. Fenoxycarb, the most active insect growth regulator examined, was found to induce a significant mortality in developing fifth stage nymphs and caused severe morphogenetic damage during ecdysis to the adult. Juvenoid treatments were also observed to increase the duration of the last nymphal stage and to induce chromotropic colour changes similar to that observed in the solitary phase of the desert locust, Schistocerca gregaria Forskal.

The relationship between corpus allatum (CA) and prothoracic gland (PG) activities has been examined during postfeeding larval and prepupal stages of en-silkworm, Philosamia ricini (Dru.). Using the isolated larval abdomen technique, the critical period of ecdysone (MH) was determined. It was 114 hr immediately after the beginning of cocoon spinning at 20 ± 2°C. To study the CA activity a histometric method was used. CA volumes suddenly increased at the prepupal stage. From these data a clear positive correlation between CA and PG activities was recognized.

Brainless Ph. ricini pupae, a highly reliable bioassay organism for detecting prothoracicotropic (PTTH)-like effects, were produced. The debraination of Ph. ricini larvae after the critical period of PTTH, produced brainless pupae. This bioassay organism was used for studying the action of juvenile hormone (JH) and MH in the metamorphic endocrine centres during the absence of the brain.

Injection of 5 μg altozar (JHA) into debrained Ph. ricini larvae accelerated pupation (12.24 ± 0.36 instead of 16.51 ± 0.19 days). Moreover the produced brainless pupae moulted to second brainless pupae. The injection of 5 μg JHA into brainless pupae or isolated larval abdominae of Ph. ricini did not show any effects. Brainless Ph. ricini moths were obtained after injecting the brainless pupae with MH (10 μg-40 μg/p). The injection of high concentrations of MH (≥ 70 μg/p) into brainless pupae activated the CA and produced pupal-adult intermediates. The present data reveal that the PTTH at low concentrations, permits the action of a JHA in the PG. Also it shows that the MH at high levels activates the CA.

The effects of larval population density and food quality on the velvetbean caterpillar, Anticarsia gemmatalis Hübner, were compared with investigations of other migratory noctuids. Crowded larvae of the velvetbean caterpillar responded with: (1) an increase in the degree of dark pigmentation; (2) a decrease in larval, pupal and adult size; (3) a prolongation of the larval stage and a decrease in weight gain in the ultimate stadium; and (4) low juvenile hormone and juvenile hormone esterase haemolymph titres.

The effects of flight, throughout a 4 hr flight period, on the haemolymph titres and whole body contents of carbohydrate and lipid are presented for the velvetbean caterpillar and discussed relative to other noctuid moths. Total carbohydrate concentration decreased during the first 30–45 min of flight, and total fatty acid concentration increased during the first 30–60 min of flight, after which it declined and stabilized at preflight levels. Lipid reserves and the small amount of lipid depletion after long periods of flight indicated that velvetbean caterpillar adults are capable of making long distance movements in which lipid is the principal flight fuel.

Juvenile hormone regulated the effect of density on larval colour, size and growth rate. Applications of juvenile hormone to crowded larvae increased the proportion of the lighter (green), larger and faster developing phase. This hormone action suggests that the juvenile hormone titre of crowded larvae is lower than that of uncrowded larvae.

Genetic differentiation among populations of velvetbean caterpillars suggests that south-central United States populations originate from overwintering populations in Mexico or south Texas. A system has been developed, using pheromone-baited bucket-type traps, to investigate the population dynamics and migration of the velvetbean caterpillar in Louisiana and Texas.