Showing papers on "Infestation published in 1969"

Studies on the helminth parasites of freshwater fishes of the Sudan

Abstract: 2419 freshwater fishes from the Sudan were examined for helminth parasites and found to harbour one monogenean species, 15 species of adult digenetic trematodes, three species of larval trematodes, 16 species of adult cestodes, 13 species of adult nematodes, two species of larval nematodes and three species of acanthocephalans. Four species of adults and four species of larval worms are recorded for the first time in the Sudan and 30 new hosts are listed. The intensity of infestation of each species, the host-specificity and the variations in the infestation of fishes are discussed. The helminth fauna of the Sudan is compared with that of other African countries.

Observations on the epidemiology of parasitic gastro-enteritis in calves.

Abstract: Over a period of seven years several series of observations were made on infestations of Ostertagia ostertagi and Cooperia oncophora on the herbage of pastures grazed by calves. A regular seasonal pattern was revealed. The concentration of larvae on the herbage falls to a low level in spring. Susceptible calves turned out at this time may begin to contaminate the pasture in mid-May but it is not until July that the infestation on the herbage increases significantly. Generally the increase is to a high level which is maintained with little change until the following spring.Evidence is presented which indicates that contamination of the pasture in the first half of the grazing season is far more effective in the production of an infestation on the herbage than is contamination in the second half of the season.In a discussion of the epidemiology of parasitic gastro-enteritis the formerly accepted view, that clinical helminthiasis results from a continuous build-up of infection in the calves and on the pasture is rejected. It appears that the parasites complete little more than one generation each year.The results of these observations suggest a simple and widely applicable means of controlling parasitic gastro-enteritis in calves.

Observations on the Seasonal Changes of the Parasite Fauna of Yellow Perch (Perca flavescens) from the Bay of Quinte, Lake Ontario

Abstract: The seasonal changes in incidence and intensity of infestation of yellow perch, Perca flavescens, by adult and larval parasites, both external and internal, were studied over a period of 1 year. Eight species of parasites were numerous enough to permit analysis of seasonal dynamics. Bunodera luciopercae and Echinorhynchus salmonis showed a high infestation in the fall and declined gradually to zero by late summer. New infestation occurred in early fall. Protocephalus pearsei showed the highest incidence in summer and a lower level during the rest of the year without any marked fluctuations. The intensity of infestation remained relatively constant throughout the year. Ergasilus confusus reached its peak of incidence in the summer, declined through the fall and winter, and began increasing in spring. Intensity of infestation showed parallel changes. In February, however, both incidence and intensity were high. Diplostomulum huronense showed a high intensity of infestation in November. The incidence remaine...

Experiments to Determine Effects of Mass Releases of Stethorus Picipes on the Level of Infestation of the Avocado Brown Mite

Abstract: Studies on the effects of mass releases of S. picipes Casey on populations of O. punicae (Hirst) were conducted in 3 avocado orchards in southern California. Multiple releases were made in 16-tree plots in each orchard at a rate totaling 400 to 500 adult beetles per tree. Releases were started when the avocado brown mite population averaged about 10 active stages per leaf in 2 of the orchards and nearly 50 per leaf in the third. In each orchard there was an earlier buildup of the S. Picipes population, a lower peak population of O. punicae , and a lower percentage of heavily bronzed leaves in the release plots compared with check plots receiving no predator releases.

Studies on the biology and control of pests of seed beans (Phaseolus vulgaris) in northern Tanzania

Abstract: Light-trap catches of Heliothis armigera (Hb.) reach peaks during the wet seasons, April and November–January. Initial infestation of seed beans by H. armigera occurs in April–May at the time of flowering of the early-sown crop, the adults probably originating from an earlier generation on maize. Two generations are completed during the main seed bean season, the first on early-sown beans and the second on later beans, and the dry period July–October may be passed in pupal diapause. Damage, caused by the older larvae eating the seeds in the pod, is prevented by spraying the young larvae with DDT (25% e.c. at 3 pt/2 gal spray/acre) (the standard treatment) or endosulfan (35% e.c. at 1½ pt/2 gal spray/acre) at about six weeks after the beans emerge.Adults of the Pentatomid Nezara viridula (L.) invade bean fields from alternative host-plants at the same time as H. armigera. This species, even in small numbers, causes the loss of young pods and also damages or kills the developing seed. It is not controlled by the standard DDT treatment for H. armigera, but the following insecticides were found to be effective: γBHC 20% e.c. (1¼ pt), dieldrin 18% e.c. (2 pt) and endosulfan 35% e.c. (1½ pt) in 2 gal spray/acre. Where N. viridula and H. armigera are found together, the standard recommendation is endosulfan 35% e.c. (1½ pt/2 gal spray/acre).The Coreids Acanthomia horrida (Germ.) and A. tomentosicollis (Stal) cause damage similar to that of N. viridula, but are serious only when infestations are heavy. They were found to be controlled by DDT, dieldrin or endosulfan at the rates given above.Alatae of the bean aphis Aphis fabae Scop, invade bean fields mainly during the first two weeks of the crop, producing apterae which concentrate on the tip of the plants. Damage (stunting, and loss of flowers and pods) is serious only when large populations of apterae are produced on a high proportion of the young plants. The early infestation demands control measures separate from those for the other pests, the most effective being methyl-demeton 50% e.c. (½ pt/2 gal spray/acre) applied 3–4 weeks after emergence. Endosulfan, although promising and far less toxic than methyl-demeton to larvae of the predator Cheilomenes lunata (F.), was discarded on grounds of cost, as was dimethoate. Aphid populations reached a peak during July and August and decreased with the warmer weather in September. A large number of alternative host-plants is listed, but the source of the primary flight into beans is not known.Melanagromyza phaseoli (Tryon), the life-cycle of which is completed in 23 days, is unimportant on seed beans as it is least abundant during the growing period of the main crop, but may damage plants suffering from water stress. Tunnelling in stems by larvae was controlled by seed dressings of aldrin or heptachlor (both 40% wettable powders mixed with seed at 1:200 w/w).

The Parasitic Copepod Mytilicola orientalis in British Columbia Bivalves

Abstract: Under western Canadian conditions infestation of Mytilicola orientalis has little economic significance in commercial oyster production. First record of natural infestation of Saxidomus giganteus i...

Impact of Cereal Leaf Beetle Larvae on Yields of Oats

Abstract: The impact of Oulema melanopus (L.) larvae on grain yields of oats was investigated in the field at New Carlisle, Indiana, in 1966 and 1968. A gradient of larval population levels was established by using varying rates of malathion in spray applications. A regression analysis of the data showed that a cereal leaf beetle larva completing development to pupation consumed 20% of the leaf surface of I stem. However, the degree of loss in yield this amount of feeding caused was influenced by the stage of development of the crop. Loss in yield ranged from 2.29 to 4.10 bushels per acre per larva per stem infestation. When infestation occurred in the 2- to 3-inch seedling stage, highest losses per larva per stem occurred. Comparable infestations caused less loss in yield when the crop had attained 6 inches of vigorous growth before it became infested.

The effect of removal of arthropod predators on an infestation of brevicoryne brassicae (hemiptera, aphididae) on brussels sprouts

Abstract: An experiment on the effect of predator removal and exclusion on Brevicoryne brassicae on Brussels sprouts is described. Five treatments were used to evaluate the effect of different parts of the predator fauna. Two syrphid species were responsible for a rapid decline in aphid numbers at the beginning of the experimental period. In two treatments where syrphids were removed a cecidomyid predator responded to the larger numbers of aphids and, in the treatment in which they were not removed, completely eliminated the aphids. In the treatment in which all predators were removed aphid numbers remained relatively high until the end of the season. ZUSAMMENFASSUNG DIE WIRKUNG DER AUSSCHALTUNG RAUBERISCHER ARTHROPODEN AUF EINEN BEFALL MIT BREVICORYNE BRASSICAE (HEMIPTERA, APHIDIDAE) AN ROSENKOHL Es wird ein Versuch uber die Wirkung der Entfernung und des Ausschlusses rauberischer Arthropoden von Brevicoryne brassicae an Rosenkohl beschrieben. Es kamen funf Verfahren zur Bewertung des Wirkungsgrades der verschiedenen Glieder der Rauberfauna zur Anwendung. Entfernung der allgemeinen Rauber und Ausschlus der Bodenfauna mit Hilfe von Klebstreifen rings um die Pflanzenstengel hatten nachweislich keinen Einflus auf die Blattlauszahl. Zwei Syrphiden-Arten, Syrphus balteatus und Sphaerophoria scripta, waren fur einen raschen Ruckgang der Blattlauszahlen zu Beginn des Untersuchungszeitraumes verantwortlich. In zwei Verfahren, bei denen die Schwebfliegen entfernt worden waren, reagierte eine Aphidoletes-Art (Cecidomyiidae) auf die groseren Zahlen der Blattlause und in einem Versuch, in dem Aphidoletes nicht entfernt wurde, rottete sie die Aphiden vollig aus. In Versuchen, bei denen alle Rauber ausgeschaltet wurden, blieben die Blattlauszahlen bis zum Ende der Saison relativ hoch.

Some effects of a porina caterpillar (Wiseana spp.) infestation on perennial ryegrass, cocksfoot, and white clover

Abstract: The effect of porina caterpillar infestation on the growth of monocultures of perennial ryegrass, cocksfoot, and white clover and on mixtures of perennial ryegrass and white clover and perennial ryegrass and cocksfoot was measured. Survival of larvae was greatest under white clover and least under ryegrass. This was attributed to differences in the availability of herbage to the larvae in their feeding zone. There was preferential feeding on white clover and cocksfoot in the mixtures with perennial ryegrass.

Egg Production by the Engelmann Spruce Beetle, Dendroctonus obesus, in Relation to Status of Infestation

Abstract: The number of eggs laid by the Engelmann spruce beetle, Dendroctonus obesus (Mannerheim), in relation to population trend was studied from 1955 to 1959 at 9 locations in western and southwestern Colorado. The number of eggs produced by the females differed considerably from year to year and seemed to be directly correlated with stage of infestation (Table 1).

Gall Formation in Aerial Parts of Plants Inoculated With Meloidogyne Jav Anica

Abstract: The formation of galls in the aerial parts of tomato, French bean and capsicum seedlings inoculated with Meloidogyne javanica (Treub) was studied. There were no differences in the type, number, and tissue of origin, of the giant cells formed in the aerial parts and in the roots of susceptible tomato and French bean plants. Both the roots and stems of capsicum seedlings were resistant to infestation.

An instance of lightning damage and infestation of ponderosa pines by the pine engraver beetle in Montana

Abstract: Lightning damage to a struck ponderosa pine (Pinus ponderosa Laws . ) } the pattern of infestation in its bole by the pine engraver beetle Ips pini (Say) (Coleoptera: Soolytidae), and the success of the pine engraver infestation of surrounding saplingand pole-size trees were documented in a western Montana study. The struck tree became infested for its entire length by bark beetles. Seventy-six percent of the immature trees within 80 feet of the struck tree also became infested. Attacks tended to be more successful closer to the struck tree and in trees in relatively moist soil. The possibility exists that the discharge that struck the mature tree may have caused undetected damage to surrounding trees and disposed them to successful attack by the bark beetles. The pine engraver beetle Ips pini (Say) (Coleoptera: Scolytidae) is an important pest of standing ponderosa pines ( Pinus ponderosa Laws.) of sapling and pole size in the northern Rocky Mountains. Most tree killing occurs during hot, dry summers when oleoresin exudation pressure is reduced and the likelihood of successful beetle attack is increased (Vite' 1961). Tree killing by this insect fluctuates greatly from year to year. Hundreds of thousands of trees, often in groups of more than a thousand, 2 may be killed during outbreaks. During years of limited pine engraver activity, the beetle confines its attacks to slash, tops of mature trees, and small groups of standing saplingand pole-size trees that often have been damaged by fire or broken off by wind or snow. Observers have long been aware that lightning-struck trees may also trigger infestations (Hopkins Respectively, Research Entomologist, in Moscow, Idaho, at Forestry Sciences Laboratory, maintained in cooperation with the University of Idaho, and Research Forester, Northern Forest Fire Laboratory, Missoula, Montana. Terrell, Tom T. 1964. Oregon pine Ips generations in the Northern Region 19621963. Unpub . rep., U.S.D.A. Forest Serv., Northern Region, Missoula, Montana. Figure 1. —Aerial view of group kill. Light-colored tree (arrow) is the lightningstruck, mature pine surrounded by dead saplings and poles. 1909; Thatcher 1960; McMullen and Atkins 1962), but little has been published about the nature of lightning damage to the struck tree, the pattern of infestation on the bole, and the extent of the beetle attack in surrounding trees as reported here. On September 12, 1966, we located a mature, lightning-struck ponderosa pine surrounded by a group of dead immature (saplingand pole-size) ponderosa pines that were infested by the pine engraver (fig. 1). This group of trees was on a narrow ridge oriented NNE-SSW at 5,000 ft. elevation about 6 miles southwest of Missoula, Montana. The drier southeast-facing side of the ridge contained an open stand of ponderosa pine and Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco). The more moist northwest slope supported a denser stand of Douglas-fir and western larch ( Larix occidentalis Nutt.). The prevailing wind is from the southwest.

Use of uric acid analysis to evaluate alfalfa seed chalcid infestation in alfalfa seed.

Abstract: A determination was made of the uric acid content of 6 replicated seed samples, 1 having no infestation, and 5 with alfalfa seed chalcid, Bruchophagus roddi Gussakovskii (Hymenoptera: Eurytomidae), infestations of 20, 40, 60, 80, and 100%. Even increments were chosen so that the data could be compared using regression orthogonal comparisons. The chemical method consisted essentially of incubating the sample with the enzyme uricase and following the optical density at 292 millimicrons with a function of time. A linear comparison among the 6 degrees of infestation was found to be highly significant at the 1% level of probability. A regression curve was plotted and was suggested to be a standard curve of infestation. Six different units contributing to the overall uric acid content found in each seed sample were analyzed for their individual uric acid content. The uric acid content for vacated seeds was determined to differ significantly from all other units, using a multiple mean comparison test. The methods employed appeared to be sensitive, accurate, and economical. Practical applications of the technique are possible.

Ticks (Ixodoidea) Of Domestic Animals In Iraq: Part 5. Infestations in the Liwas of Diwaniya and Nasiriya (spring), Karbala (winter), and Hilla (autumn and winter)

Abstract: Collections in spring from 316 animals yielded 1591 ticks; in winter from 449 animals, 3966 ticks; and in autumn from 186 animals, 3397 ticks. Their identification and incidence are given. Discussion includes a comparison with summer infestations. Meteorological data are given.

Incidence of Pine Needle Gall Fly Infestation in Pine Species Two Years Postirradiation

Abstract: The incidence of infestation by the pine needle gall fly (Itonida pinirigidae Pack) was established for two of three pine species at the Lockheed Airshield Reactor Site, Dawsonville, Georgia. Within a 25-ft-wide belt transect along a radiation gradient, three branches were obtained from all pine trees 6-12 ft high, since this gall fly infests primarily the younger trees. Significant increases in I. pinirigidae infestations of Pinus taeda and P. echinata Mill. are correlated with radiation exposures of 2,000-2,599 rads 2 years previously. No infestation was observed in P. virginiana Mill. Exposures of 125-199 rads appear to stimulate growth in needle length.

Shallot Aphid in South‐east England

Abstract: SUMMARY A relationship has been established between the departures from average of temperatures in February and March and the subsequent level of infestation of strawberry crops by the shallot aphid in south-east England. Broadly, if temperatures in February (especially) and March areaverage or below, a low level of infestation can be expected. If these months are mild, moderate or severe infestation is probable.