Louis M. Roth

Control of reproduction in female cockroaches with special reference to Nauphoeta cinerea—I. First pre-oviposition period

Abstract Prior to the first oviposition, a receptivity centre, perhaps neurosecretory cells in the brain, controls the females acceptance of courting males. In L. maderae this centre is affected by starvation. A brief exposure to food can induce mating but is inadequate for oocyte development. Before the first ovulation starvation has no effect on receptivity in N. cinerea. In N. cinerea mechanical stimulation caused by the firm insertion of the spermatophore in the bursa copulatrix releases stimuli via the nerve cord to the brain which render the female unreceptive and, at the same time, increases the activity of the corpora allata resulting in rapid development of the oocytes. The mechanical presence of the ootheca in the uterus also has two principal effects. Like spermatophore insertion, it inhibits mating. But its effect on the corpora allata is inhibitory, rather than stimulatory, and, consequently, the oocytes remain underveloped for almost the entire gestation period. The effectiveness of inhibitory stimulation from the stretched uterus depends upon the period in the reproductive cycle in which it occurs-i.e. on the physiological state of the female. In N. cinerea uterine stretching inhibits mating and oocyte development after oviposition or during gestation but is not effective when exerted during the first pre-oviposition period. In P. surinamensis, uterine stretching does not inhibit the corpora allata prior to the first ovulation but does prevent oocyte development during gestation. In fed L. maderae and N. cinerea there appears to be a synergistic action of nutrition and mating in controlling the rate of oocyte development. Mating (mechanical) and feeding (chemical) stimuli are both usually required for activating the corpora allata to their fullest extent so that the oocytes mature at their maximum rate. There is some indication that mating stimuli in N. cinerea and L. maderae are effective in further stimulating the corpora allata only if the corpora allata have reached a certain level of activity, if activating stimuli have begun to occur in the brain, or if the mating stimulus occurs in combination with nutritional factors. Thus, the corpora allata in starved virgin females of N. cinerea become sufficiently active so that some yolk is deposited in the oocytes but these oocytes do not mature; mating is effective in further stimulating the endocrine glands in these starved females and oviposition occurs in about the normal period. In starved virgins of L. maderae the corpora allata are virtually inactive and yolk is not deposited in the oocytes; mating has no effect on oocyte development in starved females. D. punctata differs from both the above species in that the corpora allata in the virgin female usually remain inactive whether she feeds or starves. Mating stimuli alone can activate the corpora allata, in fed or starved females, and consequently the oocytes mature.

Oöcyte development in Diploptera punctata (Eschscholtz) (Blattaria)

Abstract Mating stimuli activate the corpora allata in female Diploptera principally during or after insertion of the spermatophore into the bursa copulatrix and about the time the male releases the female. Copulation, prior to spermatophore transfer, is a comparatively poor stimulus for oocyte maturation. Inhibition of the corpora allata by uterine eggs during most of the pregnancy period is under nervous control. It is suggested that receptors (mechano- or pressure-receptors) which receive the stimulus from the stretched uterus become adapted during the late stages of pregnancy, or perhaps adaptation occurs in the central nervous system. Consequently, a few days before parturition, inhibition of the corpora allata ceases or is reduced, and yolk deposition occurs in the oocytes. Severing the nerve cord prior to parturition, and before the oocytes contain yolk, results in premature development of the oocytes. Transecting the nerve cord does not prevent oocyte maturation which is evidence against the hypothesis that genital stimulation, from movement of the ootheca, initiates the activity of the corpora allata.

The occurrence of para-quinones in some arthropods, with emphasis on the quinone-secreting tracheal glands of Diploptera punctata (Blattaria)

Abstract The tracheae leading to the second abdominal spiracles of nymphs and adults of Diploptera punctata are odoriferous glands which are probably used as a means of defence against predators. By infra-red and mass spectrographic analyses the odorous secretion was identified as a mixture of 2-ethyl-1,4-benzoquinone; 2-methyl-1,4-benzoquinone; and para -benzoquinone. The morphology, histology, and histochemistry of the quinone-secreting glands are described. A polyphenol oxidase and a β-glucosidase were demonstrated in the gland cells but no β-glucoside was isolated. Tracheal glands associated with abdominal spiracles are noted in several other genera of Blattaria but no quinones appear to be produced by them. Some other arthropods known to secrete quinones are listed. The secretion from the abdominal and thoracic odoriferous glands of the tenebrionid beetle Diaperis maculata was identified as a mixture of 2-ethyl-1,4-benzoquinone and 2-methyl-1,4-benzoquinone.

A sex pheromone produced by males of the cockroach Nauphoeta cinerea

Abstract Males of Nauphoeta cinerea produce a sex pheromone, principally in the abdomen, which attracts the female and functions as an arrestant, keeping her in the proper position long enough for connection to be made. The pheromone (seducin) stimulates receptive virgin females as well as females shortly after parturition. Insertion of the spermatophore in the bursa copulatrix or the presence of the ootheca in the uterus inhibits the females response to the males pheromone. Substances extracted from bodies of nine species of cockroaches (adult males and females or larvae) induce overt sexual behaviour in females of N. cinerea.

The control of sexual receptivity in female cockroaches

Abstract Female receptivity and sex pheromone production are controlled by different mechanisms. In B. fumigata females the corpora allata control pheromone production. The females pheromone releases courtship behaviour in the male; he raises his wings exposing his tergum and apparently releases a pheromone. The receptive female is attracted to the male and mounts and ‘feeds’ on his tergum. The mounting and feeding behaviour, which is indicative of female receptivity, is not directly controlled by the corpora allata. Receptivity in N. cinerea and L. maderae is determined by some event, presumably in the brain, which occurs at about the same time as the onset of activity of the corpora allata. It is suggested that the neurosecretory system is involved in acceptance of the male by the female.

A Comparative Study of Oöcyte Development in False Ovoviviparous Cockroaches

The effect of mating on o6cyte development and oviposition in Pycnoscelus surinamensis, Byrsotria [umigata, Blaberus craniifer, Blaberus giganteus, Nauphoeta cinerea, and Leucophaea maderae, all cockroaches that incubate their eggs internally, was investigated. In Diploptera punctata, the majority of females require mating for maturation of the o6cytes. In Pycnoscelus mating is unnecessary for egg maturation. Between these two extremes are species which show varying degrees of dependence on external mating stimuli for overcoming inhibition or for stimulating corpora allata. Various species also show different degrees of dependence on mating for normal formation and retraction of the o6theca into the uterus. The extent to which cockroaches depend upon food intake for stimulation of the corpora allata also varies. The species may be arranged in a series showing complete dependence to complete independence upon t:ood for o6cyte development. Experiments to determine the nature of inhibition of the corpora allata during pregnancy indicate that inhibition is due to nervous stimuli resulting from pressure of the growing eggs in the uterus.

Uric Acid in the Reproductive System of Males of the Cockroach Blattella germanica

Uric acid is stored in the utriculi majores of the accessory sex glands of the German cockroach. Most of the uric acid is eliminated during copulation by being poured over the spermatophore. Mating appears to be an important means of excretion in this cockroach.

Uric acid storage and excretion by accessory sex glands of male cockroaches

Abstract Large amounts of uric acid are stored in the utriculi majores of the accessory sex glands of males of Blattella germanica, Blattella vaga, Onychostylus notulatus, Lophoblatta n. sp., Xestoblatta immaculata, Cariblatta minima, Epilampra columbiana , and Audreia gatunae . Most of this uric acid is poured over the spermatophore during copulation. The accessory sex gland complex of male cockroaches serves a reproductive function by secreting substances which form the sperm capsule. But in the above species, the utriculi majores serve as storage excretory organs of uric acid between matings and as active excretory organs during copulation. Uric acid was not detected in the male reproductive systems of thirty-two other species of Blattaria. The known distribution of uricose glands in the Blattaria indicates that these organs were present in the blattellid-blaberid stock and have been lost in some blattellids and most blaberids.

Toxins of Blattaria

Cockroaches are probably the most pervasive of all insect domiciliary pests. As invaders of the environments we have created for our own comfort, they have established themselves in our homes, businesses, hospitals, places of food storage and preparation, transportation systems, and underground utility networks. Although the number of species involved is not great—less than 10 are true cosmopolitan pests, with some 40 others of greater or lesser local importance—the population densities these insects can attain is enormous, with the result that in many parts of the world it is virtually impossible to avoid contact with cockroaches or their products.

Stridulation by the cockroach Nauphoeta cinerea during courtship behaviour.

Abstract Males of Nauphoeta cinerea stridulate when they court non-receptive females. The stridulating apparatus consists of parallel striae on the lateroposterior margins of the pronotum and on the proximal region of the costal veins of the tegmina. The sound is produced by posterior, anterior, and side-to-side displacement of the pronotum rubbing against the costal veins. Phrases usually consist of two to six complex pulse trains followed by a long series of disyllabic chirps, and they are linked to form sentences lasting as long as 3 min. The song consists of a broad band of frequencies up to about 15 kHz with intensities of 55 to 65 dB, re 0 dB = 0·0002 dyn/cm2, at 1 cm.