Interspecific competition between two species of Trichogrammatidae III The analytical study on the competition

The experiment was carried out in order to analyze the results of interspecific competition which were mentioned in the previous reports (Sasaba 1964, 1965). The following definite tendencies were obtained and an account was given with regard to the process of competition. (1)T. minutum had a higher reproductive rate than T. japonicum at a lower density of the parent wasps. (2) The parasitic efficiency of T. minutum was high as compared with T. japonicum. (3)T. japonicum was consistently superior to T. minutum in the interspecific competition at larval stage.     

A method for estimating natural survival rate and mean fecundity of an adult insect population by dissecting the female reproductive organs

Several problems were discussed in relation toMacDonald' s method (MacDonald , 1957) for estimating the survival rate of a natural population of adults with varying survival rates and unstable age structure.

1. Random samplings with a fixed sampling ratio and an appropriate census interval is pre-requisite during the occurrence of the adults.
2. At each sampling, female adults are dissected to know the ratio, p_i, of nulliparous females in ith sample (i=0, 1, 2, 3, …,). The Σn_ip_i/Σn_i gives an estimate of the ratio, Fα/F, of nulliparous females in the population where n_i refers to the population size on ith census date. If a constant daily survival rate is assumed, the daily survival rate is estimated from equation (4′). When the survival rate is not constant over the period of adult occurrence, e. g. before and after the initiation of oviposition, the survival rate during pre-ovipositional period is estimated by equation (4″).
3. Decision of an economic census interval to obtain a reliable estimate of the ratio, Fα/F, is depending on the form of emergence curve, particularly on its duration and the length of pre-ovipositional period. If the normal distribution can be assumed for the emergence curve, an interval less than one third of the emergence period is recommended. Concerning with insects having a long pre-ovipositional period, a census interval which exceeds one third of the emergence period still gives a good estimate of Fα/F.
4. The mean realized fecundity of some kind of insects can be estimated by equation (5′ or 5″) using the estimates obtained by the present method.

     

A numerical solution of theVolterra equation for the growth of an animal population accompanying an autotoxic effect

---

Contribution from the Department of Fisheries, Faculty of Agriculture, Kyoto University.     

The consequences of flooding for the dispersal and fate of poeciliid fish in an intermittent tropical stream

Summary We studied the rainy season dispersal of the fish Poecilia gillii (Poeciliidae) from pools in a steepgradient, intermittent stream in Santa Rosa National Park, Costa Rica. The stream consisted of about 20 pools separated by dry streambed except during two floods and subsequent brief periods of flow. Individually recognizable tags permitted mark-recapture estimates of population size and information on individual movements. The first flood was very severe, with pools losing an average of 75% of their populations (range 12–99%). Most of the lost fish died by becoming trapped in desiccating pools. Males and juveniles were more likely to be lost than were females. Population loss was negatively related to pool volume and positively related to streambed slope. In addition, population loss was positively related to preflood population size when the effects of pool volume and slope were removed indicating that pools with higher densities lost more fish. Of the fish recaptured after the flood, the average proportion found in the pool in which they had been tagged varied from 16%–96%, depending on the area of the stream. Of fish that moved, 92% went downstream. The second flood was less severe though stream flow lasted as long, and there was little effect on the pool populations. Involuntary flushing during the flood and voluntary departure apparently interacted to produce the observed patterns.     

A field study of the fertility of transported equine semen

A field trial of artificial insemination in horses with transproted, chilled semen was conducted using a specially designed container which permitted a controlled, slow initial rate of cooling (-0.3 degrees C/min) and maintenance of a final temperature of 4 degrees -6 degrees C for more than 36 hrs. Forty-six mares in 23 states were inseminated with semen from three German Warmblood stallions standing at stud in Hamilton, Massachusetts. A third-cycle conception rate of 91% was obtained.     

An experimental study on the foraging behavior of a pit-building antlion larva,Myrmeleon bore

Foraging behavior of a pit-building antlion larva, Myrmeleon boreTjeder was investigated experimentally to elucidate the relation between the feeding level and pit relocation.

1. In artificial sands constructed in the field the 3rd instar larvae of M. bore rarely changed the positions of their pits, though several antlions had moved actively until they constructed pits. The average feeding rate was 0.3 prey/day/pit, and about 60% of prey captured were ants.
2. To examine whether or not M. bore larvae concentrate into the area where they can capture more prey, 8 antlions were released into each of 6 boxes filled with sand. I divided the sand surface of each box into two half areas, then gave prey to the pits built in a half area and gave no prey to the pits built in the other half. During the 50-day observation period, nonfed antlions never moved into the area where prey were given.
3. The 3rd instar larvae were reared separately without food. Even under starved conditions they rarely relocated their pits until dealth. The average duration of survival period was 83.9 days.
4. The experimental results indicate that M. bore larvae adopt a tactic of sedentary ambushing. These larvae exhibit low movement rates which are independent of prey capture rates.

     

Deletions in processed pseudogenes accumulate faster in rodents than in humans

Summary The relative rates of point nucleotide substitution and accumulation of gap events (deletions and insertions) were calculated for 22 human and 30 rodent processed pseudogenes. Deletion events not only outnumbered insertions (the ratio being 71 and 31 for human and rodent pseudogenes, respectively), but also the total length of deletions was greater than that of insertions. Compared with their functional homologs, human processed pseudogenes were found to be shorter by about 1.2%, and rodent pseudogenes by about 2.3%. DNA loss from processed pseudogenes through deletion is estimated to be at least seven times faster in rodents than in humans. In comparison with the rate of point substitutions, the abridgment of pseudogenes during evolutionary times is a slow process that probably does not retard the rate of growth of the genome due to the proliferation of processed pseudogenes.     

Assessment of isometric muscle strength and rate of torque development with hand-held dynamometry: Test-retest reliability and relationship with gait velocity after stroke

Isometric rate of torque development examines how quickly force can be exerted and may resemble everyday task demands more closely than isometric strength. Rate of torque development may provide further insight into the relationship between muscle function and gait following stroke. Aims of this study were to examine the test-retest reliability of hand-held dynamometry to measure isometric rate of torque development following stroke, to examine associations between strength and rate of torque development, and to compare the relationships of strength and rate of torque development to gait velocity. Sixty-three post-stroke adults participated (60 years, 34 male). Gait velocity was assessed using the fast-paced 10 m walk test. Isometric strength and rate of torque development of seven lower-limb muscle groups were assessed with hand-held dynamometry. Intraclass correlation coefficients were calculated for reliability and Spearman’s rho correlations were calculated for associations. Regression analyses using partial F-tests were used to compare strength and rate of torque development in their relationship with gait velocity. Good to excellent reliability was shown for strength and rate of torque development (0.82–0.97). Strong associations were found between strength and rate of torque development (0.71–0.94). Despite high correlations between strength and rate of torque development, rate of torque development failed to provide significant value to regression models that already contained strength. Assessment of isometric rate of torque development with hand-held dynamometry is reliable following stroke, however isometric strength demonstrated greater relationships with gait velocity. Further research should examine the relationship between dynamic measures of muscle strength/torque and gait after stroke.     

The feeding from edge towards inner part in soybean plot in rufous turtle dove,Streptopellia orientalis (Latham) and the estimation of passing rate of the flock

Rufous turtle dove, Streptopelia orientalis, coming to the soybean field entered it from the outer part to eat soybean cotyledons. As a result, the injured plants extended from the outer to inner parts in the field. A model expressing these behaviours was constructed here, by assuming that the amount of food birds can eat in one block determines whether they stay there or move into neighbour block. As the food decrease due to exploitation of them by birds, birds enter into farther parts with the passage of time. The rate of feeding in all visiting birds (an₀ where a is the rate of feeding per individual and n₀ the number of birds visiting) and the rate of staying at a block, b, was estimated from the field experimental results, using the above model. The value of an₀ fluctuated greatly, depending upon the season in which soybean seeds sowed. The value of b also fluctuated inversely with that of an₀, suggesting the the staying rate decreases with an increase in the number of doves coming, probably because of interference among individuals.