Numbers Of Most Species Research Articles

A Comparison of Sampling Methods for Leafhopper Vectors of X-disease in California Cherry Orchards1

The relative abundance and activity of leafhoppers in 9 California cherry orchards was estimated by using sweep net, D-vac® suction collector, sticky traps, and knockdown onto a ground cloth with pyrethrin mist. Sweep net and D-vac samples from ground cover vegetation were very similar in the relative proportions of most commonly collected leafhopper species. Yellow sticky traps hung in cherry trees at ca. 1.8 m above ground level captured most of the same species as ground vegetation samples but in markedly different relative abundance. Trap height strongly influenced the numbers of different leafhopper species captured in both yellow and in wire mesh sticky traps. There were few significant differences in the numbers of most species of leafhoppers captured in orchards with cover crops compared to orchards in which weeds were controlled. Colladonus montanus (Van Duzee) was the most abundant known vector of the X-disease agent in all sample methods. The proportion of C. montanus trapped on sticky boards relative to other leafhoppers increased with trap height, suggesting significant activity in cherry foliage compared to other vector species. Direct sampling of cherry foliage with sweep net or pyrethrin knockdown produced extremely low numbers of leafhoppers.

Insect Populations on Forage Grasses: Effect of Nitrogen Fertilizer and Insecticides 12

Significantly more leafhoppers, especially Ambylsellus curtisii (Fitch), Doratura stylata (Boheman), Draeculacephala antica (Walker), Graminella nigrifrons (Forbes), Endria inimica (Say), and Macrosteles fascifrons (Stal), were collected from nitrogen fertilized (480 kg N/ha) than from unfertilized plots of 3 grass cultivars out of 39 in 1971 and 9 out of 23 N-fertilized (240kg N/ha) cultivars in 1972. Also, more grasshoppers, Dicromorpha viridis Scudder, Melanoplus bivittatus (Say), and another Melanoplus species; the flea beetles, Chaetocnema pulicaria Melsheimer and Systena frontalis (F.); and the frit fly, Oscinella frit (L.), were collected in significantly higher numbers on some N-fertilized cultivars. Peak numbers of most insect species occurred in late summer. Carbofuran (10% granules, 2.24 kg AI/ha in 1972) and (flowable, 1.12 kg AI/ha in 1973) reduced mean numbers of most species of insects and resulted in increased dry matter yield of a few cultivars both years.

Saisonal bedingte Abundanzverschiebungen einiger Schneckenarten des Naturparks Kottenforst-Ville

Seasonal changes of some gastropod species in the Kottenforst-Ville-Park The seasonal changes of some gastropod species were examined from July 1973 to June 1974 by means of monthly quantitative samples. The highest individual numbers of most species were achieved in spring and autumn. Juveniles were abundant during these seasons.

Effects of direct drilling on the soil fauna

Numbers of most species of invertebrates were greater in the soil in which direct-drilled crops were grown. Attacks by slugs and wireworms were much less serious after ploughing. Attack by stem-boring fly larvae tended to be greater in crops in ploughed soil than those direct drilled where cereals were grown continuously. Numbers of Lumbricus terrestris were 2 to 5 times greater with direct drilling than with ploughing but numbers of other species differed much less.

Waterfowl at Loch Leven, Kinross

SynopsisA large water surface, suitable islands for nesting, extensive shallows, rich adjoining farmland and comparative peace help to make Loch Leven internationally important for waterfowl. It has long held the largest concentration of breeding ducks in Britain, consisting in 1966–72 mainly of tufted duck (500–600 pairs) and mallard (400–450 pairs), but also of gadwall (20–30 pairs), wigeon (25–30 pairs), shelduck (5–18 pairs), shoveller (up to 10 pairs) and teal (up to 10 pairs). In winter, it was important for mallard, teal, pochard and in some years for shoveler, and held good numbers of wigeon and goldeneye. These various species differed in the proportion of their food which they obtained from the loch itself. The loch also acted as a winter roost for up to 5000 greylag geese, up to 12 500 pinkfeet and up to 430 whooper swans, all of which fed entirely in nearby fields. The numbers of most species underwent regular seasonal fluctuations, with peaks and troughs in the same months each year; but different species reached peak numbers in different months. In general, waterfowl numbers were greatest in autumn, when the loch held up to 20 000 birds.The status of several species at the loch has changed markedly during the last 100 years. Some such changes were linked with general changes in the ranges and status of the species concerned, but other (more recent) ones with the reduction in macrophytes following eutrophication.

Abundance and Seasonal Distribution of the Tabanidae1 of the Great Swamp, New Jersey. Part II. The Second Year2

Continuation of a tabanid faunal study in a hardwood swamp in north-central New Jersey in 1967 produced 8678 adults representing 37 species—17 in Chrysops, 13 in Tabanus, and 7 in Hybomitra. In the 2-year study, 43 species in 4 genera were collected. The 1966 and 1967 faunas were very similar; only 8 species were collected in only 1 year (7 of these represented by 1 specimen). Hybomitra lasiophthalma (Macquart), Tabanus lincola F., T. pumilus Macquart, and Chrysops vittatus Wiedemann were included in the 5 most abundant species in both years. The order of seasonal succession for each species was similar in the 1966 and 1967 faunas; annual in differences in date of appearance were marked only for C. celatus Pechuman (10 days) and T. similis Macquart (90 days). Peak numbers of most species appeared at about the same time in 1967 as they had in 1966. Considering-their small numbers, C. unvittatus Macquart, T. sparus var. milleri Whitney, and H. epistates (Osten Sacken) had long seasons as they had in 1966. The distributions of most dominants were more attenuated in 1967 than in 1966. Bacillus cereus Frankland & Frankland, a soil saprophyte, may have caused high mortality of C. vittatus populations in 1967.

邦産キク亜科植物の細胞学的研究(VI). ヨモギ属 (Artemisia) の核型分析

1. The karyotypes of eight species in the genus Artemisia were studied by the smear method with the pretreatment of 8-oxyquinoline.2. The chromosome numbers of A. apiacae and A. montana are here reported for the first time, and for A. montana, a number different from the previous determinations has been recorded.3. Based on the karyotypical stand point, A. princeps and A. montana seem to be amphidiploid forms of a basic number of 17 and 26, respectively.4. The common karyotypical characteristics of the genus Artemisia are represented by the existence of a pair of short chromosomes with subterminal constrictions and of the larger chromosomes which have the secondary and terminalized primary constrictions. And the karyotype is generally symmetrical.5. A. montana may be derived from some species with the same chromosome number of 2n =18 as in A. stelleriana by a loss of a pair of trabants of median-sized chromosomes which have secondary constrictions and show variations in some other minute karyotype details.6. The basic chromosome number of most species in the genus Artemisia appears to be 9. However, in A. Feddei, a diploid number of 16 was observed. Some species with higher chromosome numbers (2n =34, 52) are presumably of amphidiploid origin.