Follicular Relics Research Articles

Gonadotrophic Cycles in the Face Fly, Musca autumnalis123

Gonadotrophic cycles were studied in Musca autumnalis De Geer, by observing physical changes in the ovaries after the completion of a known number of cycles, and by observing oviposition by individual females. Nulliparous and parous females could be distinguished in all cases, primarily on the basis of the follicular relics which occurred in the. parous females. Ovarian follicular relics were observed in several forms in parous females, and distinctions among uniparous, biparous, and triparous individuals were possible. Under the experimental conditions used, the first uniparous, biparous, and triparous females were 4, 7, and 10 days old, respectively. Most of the females completed 2 gonadotrophic cycles within a 12-day period following emergence, the first by 6–7 days and the second by 10–11 days.

Biological Studies on Ceratina dallatorreana, an Alien Bee in California Which Reproduces by Parthenogenesis (Hymenoptera: Apoidea)2

Ceratina dallatorreana , Friese is native to the Mediterranean region, where both sexes are present. The first bees appeared in the upper Sacramento Valley of California in 1949 and the species has since spread southward to the lower San Joaquin and Santa Clara Valleys. The life history in California is reconstructed by using the structure and contents of the nests, the immature stages, and certain anatomical features of the females, including the amount of wing wear, contents of the gut and spermatheca, development of the ovaries, presence of follicular relics, and the condition of the fat body. The species reproduces primarily by thelytokous parthenogenesis, but rare instances of insemination are detected and 1 male has been collected. Considerable variation in color is present and may be the result of automixis. At least 2 generations a year occur and the adults overwinter in solitary burrows. The nests of the bee are small and have a water-repellent lining which is apparently derived from glands on the second and third sterna. Preference for weedy plants as sources of food and nesting media has contributed to the success of the bee in an area of intense agricultural activity.

Age‐changes in the ovaries of the sheep ked, Melophagus ovinus (L.) (Diptera: Hippoboscidae)

SYNOPSISThe reproductive system and ovulation cycle in Melophagus ovinus are described, and age changes in the ovaries are discussed. A method, similar to that used with Glossina spp., for determining the age of individuals by examination of their follicular relics is proposed.

Methods for Distinguishing Nulliparous from Parous Flies and for Estimating the Ages of Fannia canicularis and Some Other Cyclorraphous Diptera

Methods reported by Russian workers for separating parous from nulliparous muscoid flies and for distinguishing old from young were confirmed and extended to several previously unstudied species; and it is suggested that the characteristics used in this study may possibly be applicable for most Anthomyiidae, Calliphoridae, Muscidae, and related families. The presence of follicular relics in the ovariole pedicels and lateral oviducts of parous flies was the character primarily used to distinguish them from nulliparous; other characteristics used were the presence or absence of pupal fat body, the number of tracheal skeins in the ovaries, the number of functional ovarioles, and the compactness of the ovarioles. Tracheal skeins were considerably less numerous in parous than in nulliparous flies, and in both categories flies could often be separated into young and old age groups. Uniparous, gravid females were the most difficult to identify as being parous because of the small amounts of follicular remnants at the bases of the fully developed eggs. As the number of ovipositions per female increased, so did the quantity of relics accumulated. The number of functional ovarioles decreased as the number of gonotrophic cycles increased. From these changes it was possible to estimate the ages of wild flies. In test series of laboratory-reared flies all misidentifications involved uniparous, gravid females which were identified as nulliparous; nulliparous flies were never misidentified as parous. Fannia canicularis (L.) matured its eggs only when provided with a protein diet; the eggs of gravid females were not resorbed when the flies were starved or provided with a water or sugar-and-water diet. Other miscellaneous observations on gonotrophic phenomena and oviposition are presented. Other species studied in the laboratory, using females of known ages, were Musca domestica L., Muscina stabulans (Fallen), Myospila meditabunda F., and Orthellia caesarion (Meigen). Wild specimens of all these species, as well as of Calliphora terraenovae Meigen, Ophyra leucostoma (Wiedemann), and Stomoxys calcitrans (L.), also were examined.

On the Determination of the Approximate Age of a Black Fly (Diptera: Simuliidae) and its Significance

Female black flies may be sorted into two age groups, the nulliparous and the parous, by the changes in the ovary including the absence or presence of follicular relics. This highly accurate method, developed in Russia and England for Anopheles mosquitoes (Beklemishev 1944; Lewis 1958a), has been recently adapted for use with black flies (Lewis 1958b; Davies 1961).

Determination of physiological age for female Glossina morsitans.

RECENTLY, considerable attention has been paid to a method of determining the physiological age of female insects of economic importance by the appearance of the ovarioles after ovulation. This method, which was originally worked out by Soviet entomologists1,2 for Anopheles, and has since been extended to other blood-sucking Diptera, depends upon the recognition of the number of follicular relics (‘corpora lutea’) appearing as dilatations of the follicular tubes. Each dilatation represents the relic of a single egg follicle and is evidence of a gonotrophic cycle. If the duration of the cycle is known it is possible to calculate the calendar age of the female, a factor of great practical application in determining the epidemiological importance of populations of insect vectors or the degree of success of control programmes. In the laboratory, Bertram and Samarawickrema3 recognized Mansonioides uniformis which had completed five gonotrophic cycles by the presence of five dilatations in the follicular tubes. A study of the ovarioles of Glossina morsitans after ovulation has been made, and it is suggested that a similar method of determining the physiological age of female tsetse flies should be possible.

Observations on the Simulium neavei complex at Amani in Tanganyika.

The paper deals with two members of the Simulium neavi Eoub. complex found at Amani in the forest of the Usambara Mountains, Tanganyika Territory. They have already been described but are at present termed the Amani unhanded and banded forms, scientific names being witheld until the taxonomy of the whole complex is better understood.Some methods of study are described.Pupae of the unhanded form constituted a large proportion of the total number found on the common local crab, Potamon (Potamonautes) lirrangensis Eathbun, which amounted to roughly one pupa to seven crabs. This form predominated in the lower and more open parts of the drainage system examined. The adults were not seen to bite man. This and the banded form were found at a much lower altitude than any hitherto reported for the complex, probably owing to the particular nature of the local climate. Neither form was abundant.The larvae and pupae of the banded form, like the unhanded one, live externally on the crabs. The variability of wing size of the banded form is described. Observations were made on the internal anatomy of the adult with special reference to the ovaries in which the follicular relics are usually very large, indicating that the female probably bites soon after laying eggs. As in S. damnosum Theo. there is an easily recognisable class of old flies with clear Malpighian tubes. Nulliparous and parous flies have rather different biting cycles. The banded form bit man readily but only about five were taken per hour in good catching places and far fewer elsewhere.Human onchorcerciasis has been reported from Amani but is not known to do any harm there. The existence of the disease in the presence of rather small numbers of Simuliids is of interest in relation to a belief that S. neavei is a more efficient vector of onchocerciasis than is S. damnosum. Out of 359 banded females dissected 41·2 per cent, were parous and 12·8 per cent, of these were infected with nematodes, at least some of which were not Onchocerca volvulus.Taxonomy, the ovarioles and the Simuliid-crab association are discussed. The formation of the large follicular relics of the banded form is considered in relation to the history of the follicular epithelium before and after ovulation. The crab association is regarded as commensalism-, and it is suggested that the crabs benefit the Simuliids by carrying them a short distance to a suitable current and that they thus enable them to live in fast rivers and so extend their range.