Aedes Mosquitoes: The Universal Vector
Jagriti Narang, Manika Khanuja in Small Bite, Big Threat, 2020
The gonotrophic cycle of mosquitoes, as defined by Beklemishev (1940), is the search for a host, ingestion of a blood meal, digestion of the meal, maturation of ovaries, and laying of mature eggs after searching an oviposition site (Beklemishev, 1940). A fully matured female mosquito prepares itself for the next stage by finding a host, preferably a vertebrate host. It feeds on the blood until its gut is filled, and sometimes it can consume blood even more than its body size (Fig. 1.21). This can be seen sometimes when blood starts oozing out of its body. After blood sucking, the female then rests on some comfortable surface for some time (Birley and Rajagopalan, 1981). Blood is necessary for the development of oocytes. For egg laying, the female prefers containers or small niches filled with water and lays eggs on the surface (ovipositioning), a bit above the water line, ensuring delivery of the first larval instars born in the water. The egg released by the female is a fertilized one, formed when the oocyte meets the sperm while traveling down the common oviduct before releasing out from the vagina (Briegel, 1990). The sperm enters the oocyte through the micropyle. The female then looks for some site for ovipositioning and starts laying eggs. A single mosquito can lay hundreds of eggs in batches. Usually it undergoes three gonotrophic cycles, but in each cycle, it can consume more than one blood meal from a host as per its body needs (Beklemishev, 1940). After releasing the eggs, a permanent structural change can be seen in the female’s abdomen, which can be observed if one wants to keep a record of the female’s reproductive history and, thereafter, her age (Birley and Rajagopalan, 1981).
Pharmacognosy and Pharmacopoeial Standards for Syzygium cumini
K. N. Nair in The Genus Syzygium, 2017
The dried fruits contain one or two seeds that are compressed together into a mass resembling a single seed. Seeds are oval to roundish, brownish-black, and about 1.5–2 cm long and 1–0.5 cm wide. The whole seed is enclosed in a cream-colored coriaceous covering. The testa is light brownish in color. It can be easily separated from the kernel, which consists of irregularly folded dark violet to brownish cotyledons. Near one end of the seed is the hilum, which forms a circular slightly elevated scar on the testa and a grooved micropyle adjacent to it. The embryo consists of two large cotyledons enclosing a radicle and plumule (Figure 7.1b and c) (Anonymous 2008).
The Protozoa
Donald L. Price in Procedure Manual for the Diagnosis of Intestinal Parasites, 2017
Oocysts of I. belli are light-bulb shaped, being nearly oval but narrowing bluntly at one end (see Plates 6, 40). Occasionally, they are oval. A small plug-like spot, the micropyle, lies in the center of the narrower end. After the combination of the two gametes, the zygote forms an outer cyst covering to become an oocyst. Within the oocyst wall, the zygote divides to form two sporoblasts. Each sporoblast secretes a cyst wall to become a sporocyst. Within the sporocysts, four sporozoites develop along with a residual body (see also Plate 70).
Assessment of gamma radiation through agro-morphological characters in camellia sinensis L. (O.) kuntze
Published in International Journal of Radiation Biology, 2023
Shobhit K. Singh, Devajit Borthakur, Abhijit Tamuly, J. G. Manjaya, Pradeep K. Patel, Boby Gogoi, Santanu Sabhapondit, Nabajyoti J. Neog, A. K. Barooah
Tea (Camellia sinensis L.) is a long duration, cross-pollinated, entomophilic, perennial cash crop, and most popular refreshing beverage. Tea green leaf is the raw material for all the varieties of tea and two leaves and a bud is a viable parts of the tea plant which are utilized for the making of good quality tea. It is a labor-intensive industry because the best leaf is best plucked by fingers. Since the beginning of the commercial cultivation of tea in Assam in 1937 tea was exclusively grown from seeds up to 1950. Thereafter, seeds were produced by a large number of tea estates by raising Assam, China, and Combo genotypes on a commercial scale. Botanically, it belongs to the family Theaceae and attracts a high volume of foreign cash to the country. Singh et al. (2015) reported that about 204 tea planting materials are available for commercial planting to date. Singh (1980) advocated that for producing high-quality tea with a high production rate it would be necessary to improve the existing tea varieties with the help of the non-conventional technique of breeding. Barman (2011) explained that tea seed is circular marble-like and surrounded by a dark brown or black hard shell. The seed population is a mixture of genetically diverse genotypes, they can adapt to a wide range of environmental conditions without much variation in their overall performance. Barua (2008) described that there is two way of planting: one, with the help of seed from seedbarie; and the other, by growing leaf cuttings from the mother bush. After collection of seeds from the seed barie, seeds are brought to a central shed and passed through a rotatory type sifter to eliminate the very small seeds. The mesh size used for the elimination of small seeds should not determine arbitrarily; it should correspond to the model seed size of the barie. After eliminating the very small seeds, the remaining seeds are transferred to a tank or a trough filled with water and allows soaking for 2-3 hours. The sinker seeds are taken out of the water and spread on a concrete floor, plastic sheet until the adhering water evaporates. The store seeds are again put through the sinker-floater test. Floaters are discarded and the sinkers are examined for the germination test. If the seed is stored well with a good level of moisture, the germination percentage of the tea seeds is 85 − 90 percent. The nursery technique for seed propagation of the tea plant is well defined by Barua (2008). Accordingly, two major things are important, the first is soil pH (pH 5.0) and the Second is good soil texture free from parasitic eelworms is satisfactory for nursery practices. Tea seeds are planted in rows as soon after harvest as possible to a depth of about 1.5 cm with the eye (micropyle) pointing downward or parallel to the ground surface. When sowing the seeds cover the seedbed with a thin layer of mulch and the seeds may get germinate within a month of planting. Pre-germinated seeds can also be used but the nature of the experiment is more suitable to get maximum advantage of radiated materials.
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