Robert H. Barth

PHYSIOLOGY OF THE REPRODUCTIVE CYCLE IN THE COCKROACH BYRSOTRIA FUMIGATA (GUÉRIN)

1. Four reproductive processes (vitellogenin secretion, yolk deposition, colleterial gland activity and pheromone production) are initiated on about the fifth day after adult ecdysis. There is no apparent sequence of initiation of these processes except that vitellogenin secretion either precedes or occurs concomitantly with the initiation of yolk deposition.2. Two blood proteins, which are female-specific yolk precursors (vitellogenins A and B), reach a concentration peak on day 16 and then decrease in response to rapid yolk deposition. A second peak on day 22 is thought to represent yolk precursors which were released to the blood as a result of the resorption of some basal oocytes. The vitellogenins are either absent or occur in trace quantities in the blood of pregnant females.3. Sex pheromone is detectable on the surface of the cuticle by day 10 in 94% of the females tested. Following mating pheromone production is drastically curtailed.4. Glucoside activity in colleterial glands increases almost lin...

Initiation and regulation of oöcyte growth by the brain and corpora allata of the cockroach, Nauphoeta cinerea☆

Oocytes of Nauphoeta cinerea begin to grow about 2 days after adult ecdysis. This growth can be totally prevented by surgical ablation of the corpora allata (CA) before day 2 and restored in a dose-related manner by injection of juvenile hormone (JH). Ovarian maturation can also be prevented in some animals by brain extirpation within a day of adult ecdysis but proceeds normally in others, indicating that the brain acts to promote oocyte lengthening very soon after emergence. Wounding (mouthparts removal) blocks ovarian maturation in a similar percentage of animals, indicating that the ‘wounding effect’ is mediated by the brain. However, those wounded animals which do develop oocytes do not reach normal values by autopsy on day 7, suggesting a temporary inhibition of the CA. Because the effects of head ligation, which effectively removes the brain as well as the CA, can be reversed by only a little more JH than the effects of allatectomy, we conclude that the primary role of the brain is to control the CA. We suggest that both stimulatory neurohumoral material and inhibitory nervous transmission may be utilized for this control.

Quantitative aspects of the male courting response in the cockroach Byrsotria fumigata (Guérin) (Blattaria)

Male cockroaches, Byrsotria fumigata , respond to the female sex pheromone by increased locomotory activity. An initial peak in activity is followed by a linear decrease until a basal level is reached. Habituation occurs when males are constantly exposed to sex pheromone, and a period of 96 hr is required for complete recovery. The activity of males is proportional to the concentration of female sex pheromone. Females begin secreting quantities of pheromone detectable by males within 4 days after adult emergence, and males respond to pheromone sources on about the third day after emergence.

Hormonal control of diglyceride metabolism during vitellogenesis in the cockroach, Eublaberus posticus

Abstract During a vitellogenic cycle in the ovoviviparous cockroach Eublaberus posticus, more than 100 mg of lipid is transported from the fat body to the developing oocytes. Lipid is very likely transported in the form of diglyceride (DGL), because 1-14C-glycerol injected into the haemocoel is preferentially incorporated by the fat body into DGL, and labelled DGL rapidly appears in the oocytes as well. Two main lines of evidence suggest that lipid transport is under the control of juvenile (gonadotropic) hormone: (1) DGL accumulates in unusual quantities in both ovaries and fat body following allatectomy, although vitellogenesis is superficially brought to a halt within one day of surgery, (2) fat body dissected from allatectomized cockroaches synthesizes only 25% as much 14C-DGL from labelled precursors as does tissue from controls.

Physiology of feeding-preference patterns of female black blowflies (Phormia regina Meigen): Alterations in responsiveness to salts

Abstract Electrophysiological recordings of tarsal and labellar contact chemosensilla in Phormia regina females demonstrate activation of sugar-, cation-, and possibly anion-sensitive cells in response to 10% yeast extract. Yeast extract is a proteinaceous food source that supports full egg development. Though some protein is required for egg maturation in Phormia, a blowfly not normally autogenous, purified proteins alone neither activate the chemosensilla nor promote egg development. In experiments reported here, groups of females were given ad lib access to either 0.2 M sucrose or 0.2 M sucrose and 10% yeast for four days after eclosion. The sucrose diet induced a ‘protein’ preference but no egg development. Potassium and sodium salts were added to 0.2 M sucrose and presented to the flies on day six. The volumes of salt-sucrose mixtures taken were greater than those of 0.2 M sucrose for flies raised on 0.2 M sucrose, though yeast was preferred over all but one salt solution. For sucrose-and-yeast-fed flies, volumes of 0.05 and 0.1 M salt mixtures consumed did not differ from 0.2 M sucrose; however, sucrose alone was favoured over more concentrated salt mixtures. All salt-sucrose mixtures tested were significantly more effective stimuli for sucrose-and-yeast-fed flies than yeast. It is suggested that varying sensitivity in the salt-sensitive contact chemosensilla plays a role in reported food preference shifts associated with reproduction.

Insect juvenile hormone mimics: a structural basis for gonadotropic activity in a cockroach and a moth

Abstract Exogenously applied natural juvenile hormones (JH) and some synthetic JH mimetic substances resulted in dose-related gonadotropic responses and were able to fully substitute for the absence of endogenous JH in a moth and a cockroach. Aliphatic methyl and ethyl esters, thio esters, and amides were most active. Some aromatic JH mimics with high activity in morphogenetic assays on a variety of insects showed little activity in the gonadotropic bioassay. This suggests that the ovaries of the moth Manduca sexta and the cockroach Nauphoeta cinerea respond primarily to the intrinsic JH activity of the test substances.

Physiology of feeding-preference patterns of female black blowflies (Phormia regina Meigen): Modification in responsiveness to salts subsequent to salt feeding

Abstract Behavioural experimentation on Phormia regina shows that females previously fed only sucrose, and thus in a state of yeast preference, will ingest single-salt-sucrose mixtures in volumes similar to that of 10% yeast (Rachman et al., 1982). In particular, females will ingest NaCl 0.1 M in 0.2 M sucrose in volumes not statistically different from 10% yeast. In the experiments reported here, groups of females were given ad libitum access to both 0.2 M sucrose and NaCl 0.1 M in 0.2 M sucrose from days 0–4 after eclosion. Potassium and sodium salts were added to 0.2 M sucrose over a spectrum of concentrations and presented to the flies on day 6. The flies rejected all single-salt-sucrose mixtures offered. Even when the pre-test sodium salt was changed to a potassium salt during days 0–4, the flies still rejected the single-salt-sucrose mixtures offered subsequently. However, when sodium and potassium salts were mixed together in 0.2 M sucrose, females ingested the solutions in amounts similar to 10% yeast. Several different concentrations of the double-salt-sucrose solutions were ingested in volumes not statistically different from 10% yeast. Results support the underlying hypothesis that activity in the salt-sensitive chemosensory neurones is involved in protein preference.

Lipid metabolism during oöcyte growth in the ovoviviparous cockroaches Eublaberus posticus and Nauphoeta cinerea

Abstract Lipid comprises nearly 30% of the fresh weight of newly oviposited oocytes of the cockroaches Eublaberus posticus and Nauphoeta cinerea. It is incorporated rapidly during the first 10 to 12 days of adult life, presumably deriving from fat body triglyceride (TGL) which is depleted at a similar rate. The most rapid stage of ovarian TGL uptake is preceded by a sharp increase in the rate of incorporation and a peak in the total amount of diglyceride (DGL) in the ovaries, indicating that yolk lipid has been sequestered from the DGL-carrying proteins of insect haemolymph.