Reproduction maturation

A parasite must reproduce to complete its life cycle successfully. In this sense, the ability of an H. glycines individual to parasitize a soybean plant is measured by reproduction. In general, resistant hosts do not permit the female nematode to develop to reproductive maturity. Parasitism is a qualitative trait that the individual nematode either does or does not possess. In addition, nematode populations may be described quantitatively by their level of reproduction on a given host plant. Field populations of H. glycines... 

Multigenerational Study. This approach involves the continuous exposure of a rodent species (usually mice). The parental animals are exposed shortly after weaning (30-40 days of age). At reproductive maturity, the animals are mated. The first generation is produced (Ff. From these an F2 is produced and then subsequently an /) generation. The effects of the test is monitored through each generation. The measured parameters include fertility, litter size, and neonatal viability. This is a time-consuming effort that usually takes about two years to complete. 

A further complication arose when it was discovered that in the Mediterranean fruit fly Ceratitis capitata (Diptera Trypetidae) the corpora allata of adult virgin females produce, in addition to JHB-3, smaller amounts of methyl palmitate and less of JH III.97 Mated females produced much less methyl palmitate. It is suggested that methyl palmitate may be a default product of methylation, in the absence of JH, but it does not rule out the possibility that it also participates in some way in reproductive maturation and control, because its presence is correlated with the period of nonreceptivity toward mating in adult females of... 

The molting and other hormonal activities of the ecdysteroids are, of course, modulated by the titer of the insect juvenile hormone and the two materials typically function in close concert with one another in dictating insect molting and metamorphosis as well as in reproductive maturation (21). 

The synthesis of juvenile hormone (JH) in the insect corpora allata (CA) is controlled by an array of inhibitory and stimulatory factors originating in different parts of the retrocerebral complex and in the ovary. The nature of the factors involved and their interactions seem dissimilar in different insect groups, and it is premature, based on what is known to date (1.2), to formulate a unified model of allatal control for all insects. Differences may truly exist, however they may be a consequence of information inadequate to generalize from. Rather, we present herein a model of allatal control in the adult female locust during reproductive maturation, which may serve... 

Like JH III in insects, MF seems to play a role in enhancing crustacean reproductive maturity, as well as maintaining the juvenile morphology [123]. The synthesis of JH HI in insects is also regulated by neuropeptides, one group of regulators (the allatostatins) is, in fact, similar in structure to neuropeptides that have been isolated from crustaceans (see Section 3.3) but there is no structural resemblance between the allatostatins and the MOIHs and there is no report on the role of allatostatins in regulating the crustacean MOs. 

Bioassay-guided fractionation also resulted in identification of a male-attracting pheromone from the urine of reproductively mature female masu salmon (Oncor-hynchus masou). The active compound appears to be L-kynurenine (Fig. 24.2), a major metabolite of L-tryptophan. This pheromone elicits a male-specific behavior at pico-molar concentrations (Yambe et al. 2006). For a review of the progress in crustacean sex pheromone detection and identification, interested readers can refer to the chapters of Kamio and Derby (Chap. 20) on identification of blue crab sex pheromones, and of Hardege and Terschak (Chap. 19) on the identification of shore crab sex pheromone. 

Describe various situations where prediction of life span, maturation time, reproductive maturity, and generation time would be important. 

Frogs used for the tests were reproductively mature to ensure the presence of any signals linked to sexual readiness. Males were considered mature if they developed black nuptial tubercles on the palm, forearm, shoulders (ventral surface), and chin (Daugherty and Sheldon, 1982a). Females were considered mature if eggs were visible through their... 

In this experiment, we built an apparatus for a three-way choice test. The three treatments were male-conditioned water, female-conditioned water and control water. Each water treatment was conditioned by placing two reproductively mature frogs in 19 L of water for 24 hours. Control water was prepared at the same time and placed under the same conditions for 24 hours. 

Getz, L. L., Dluzen, D. McDermott, J. L. 1983. Suppression of reproductive maturation in male-stimulated virgin female Microtus by a female urinary chemosignal. Behav. Processes 8 59-64. 

There are three general mechanisms by which responsiveness to pheromones could be coordinated with reproductive maturity 1) reproductive hormones might directly affect primary receptor structure or function, 2) olfactory bulb activity could be modulated by efferent, hormone-sensitive fibres from the brain, and 3) the occurrence of appropriate behaviors could be influenced by hormone-dependent changes in sexual motivation. 

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