Showing papers on "Infestation published in 1979"

Insect Pests of Grain Legumes

Abstract: A review is presented of the principal arthropod pests of pulse crops in the tropics. The pests are grouped taxonomically but are discussed roughly in the order in which they colonise a crop. Pests of stored legumes are not dealt with, even though in some cases infestation begins in the field. Information is presented on distribution, damage, the life-cycle and control of leafhoppers, aphids, beanflies, beetles, Lepidoptera, thrips and pod-sucking Hemiptera. Future strategies for pest control are discussed

Beech bark disease: patterns of spread and development of the initiating agent Cryptococcusfagisuga

Abstract: Beech bark disease occurs when beech trees, predisposed by infestation of the beech scale Cryptococcusfagisuga (Lindinger) (C. fagi (Baer.)), are infected by species of the fungal genus Nectria. Infestation patterns of C. fagisuga on individual trees and in forest stands were studied. Fagussylvatica L. was infested artificially with C. fagisuga. After 3 years, secondary colonization on individual trees was generally restricted to within 1 m from points of introduction. Cryptococcusfagisuga was associated positively with the bark lichen Lecanoraconizaeoides Nye ex Cromb. and negatively with the bark fungus Ascodichaenarugosa Butin. In a young plantation, patterns of scale infestation were related to distance from a large old relic tree and to wind-direction records for the insect's dispersal period. In another plantation the infestation patterns were associated with site topography. In North America, the pattern of continuous spread of C. fagisuga (and of associated disease development) since its introduct...

Physiological Responses to Spider Mite Infestation on Strawberries

Abstract: The effect of various infestation levels expressed as mite-days, of Tetranychus urticae Koch on the chlorophyll content, transpiration, and photosynthesis of strawberry leaflets was studied. No reduction in chlorophyll content was observed at any infestation level, but transpiration and photosynthesis were reduced at low levels of 2.5 and 5.0 mite-days/cm2. Transpiration decreased rapidly by 42% at densities up to 15 mite-days/cm2, but at higher densities reduction was gradual and resulted in only an 11% reduction for an additional 35 mite-days/cm2. Photosynthesis was similarly affected at the low feeding levels (2.5–15 mite-days/cm2) but continued to decrease linearly with increasing infestation levels resulting in a 60% reduction at 50 mite-days/cm2. The effect of mite feeding on stomatal opening and functional integrity of leaf tissue is discussed.

Effects of Varying Twospotted Spider Mite Infestation Levels on Strawberry Yield

Abstract: Varying infestation levels of Tetranychus urticae Koch were created on strawberry plants by application of cyhexatin at density treatment levels of 0–5, 25, 50, 75, and 100 mites/leaflet, and subsequent yield responses were determined. Seasonal accumulations of 15597, 6261, and 6768 mite-days/leaflet in the untreated controls in 1976, 1977, and 1978, respectively, significantly reduced yield in comparison with cyhexatin treated plots. No yield differences occurred between plots treated at 25, 50, 75, and 100 mites/leaflet, although seasonal mite infestation levels ranged from 781 to 3631 mite-days/leaflet and from 1 to 4 cyhexatin applications were required. Four to 7 cyhexatin applications were necessary to maintain mite infestation below the 0–5 mites/leaflet level, and in 1977, these plots yielded significantly less than plots with higher mite treatment levels. Thus, an acaricide application at a density treatment level of 50 mites/leaflet would provide effective T. urticae control on summer planted strawberries in southern California. Predatory arthropods did not regulate mite populations in these studies. Seven predators were present with predominant species being the sixspotted thrips, Scolothrips sexmaculatus (Pergande), in 1976 and 1977 and a cecidomyiid, Arthrocnodax occidentalis Felt in 1978.

The infestation of crops of oil-seed rape ( Brassica napus L.) by insect pests

Abstract: Summary During 3 years a total of ten crops of winter rape and two crops of spring rape were sampled for insect pests and pest damage once or twice a week from the green bud stage to just before harvest. The most common pests were Meligethes aeneusFab., and Ceutorhynchus assimilisPayk.; the former was usually the more numerous, especially on spring rape crops. Ceutorhynchus quadridensPanz. and Dasyneura brassicaeWinn. were less abundant. C. assimilisand M. aeneus immigrated to winter rape crops when temperatures exceeded 15 °C. Maximum infestation of M. aeneus occurred either at the green bud stage, or when flowering began or at full flower depending on temperature; maximum infestation of G. assimilis occurred during flowering, which varied in time from mid to late May. In response to changing temperatures successive waves of immigration sometimes occurred. Immigration to spring rape occurred at green bud stage. The two methods used for sampling pests, sweep nets and water traps, gave different results. Water trap collections primarily reflected pest flight, and were not necessarily related to the pest population on the crop. Ovary maturation of M. aeneus occurred between their emergence from hibernation and migration to winter rape. They began laying 3 weeks after their arrival on winter rape but immediately they arrived on spring rape. The proportion of male to female M. aeneus present on crops was variable. C. assimilis fed for 3–4 weeks after their arrival on winter rape before their ovaries developed and they mated. On both winter and spring rape the number of M. aeneus declined during flowering and that of C. assimilis declined while pods were maturing. Their decline on winter rape was associated with their emigration to new host plants. New generation M. aeneus emerged before winter and spring rape were harvested, and new generation C. assimilis emerged before spring rape but not winter rape was harvested. The implications of these findings are discussed in relation to pest control.

Time of Tuber Infestation and Relationships Between Pheromone Catches of Adult Moths, Foliar Larval Populations, and Tuber Damage by the Potato Tuberworm

Abstract: Time of tuber infestation by Phthorimaea operculella (Zeller) was markedly affected by the type of irrigation system employed. Tuber infestation under furrow irrigation was above 25% for 4 wk prior to vine senescence while sprinkler irrigated potatoes sustained less than 5% damage during this period. After irrigation was terminated, infestation increased rapidly in sprinkler irrigated plots. Tuber infestation continued to increase in all irrigation blocks late in the season, but rows which were hilled and rolled sustained less damage than ones which were only rolled. Larval populations in the foliage and moth counts in pheromone traps increased during the season and were significantly correlated. Under furrow irrigation, pheromone trap catches and larval counts in the foliage were significantly correlated with tuber damage.

The Parasite Complex of the Forest Tent Caterpillar in Northern Minnesota

Abstract: The parasites of the forest tent caterpillar, Malacosoma disstria Hubner, were studied during the last 6 yr of the 1964–72 outbreak in northern Minnesota. Egg parasitism, only ca. 4–10%, involved 3 species: Telenomus clisiocampae Riley, Ooencyrtus clisiocampae (Ashmead), and Tetrastichus silvaticus Gahan. Twenty-five hymenopterous species and 13 dipterous species were reared from the larvae and pupae of the forest tent caterpillar. Six of the hymenopterous species were hyperparasites, while 6 of the dipterous species were scavengers. Rogas sp. was the only early larval parasite. The most abundant late larval parasites were Patelloa pachypyga (Aldrich and Webber), Leschenaultia exul (Townsend), Lespesia frenchii (Williston), and Trichonotus analis (Say). Pupal parasitism was highest on cocoons from the ground level and progressively lower in the shrub and crown levels. Pupal parasitism increased with age of the infestation until 1968, decreased significantly in 1969, then increased again until the population collapsed in 1972. Sarcophaga aldrichi Parker and tachina flies accounted for 98% of all parasitism in the late cocoon collection during 1967–71 except in 1970. S. aldrichi destroyed all other parasites in the pupae and became the over-whelmingly dominant parasite in pupae after the 1st year of heavy infestation. Itoplectis conquisitor (Say) was common during the 1st year of heavy infestation. Otherwise, ichneumon wasps were rare in the late cocoon collections except in areas at the edge of the outbreak. The biology and individual patterns of parasitism during the outbreak are discussed for the common parasites.

Potato Tuherworm Damage to Potatoes Under Different Irrigation and Cultural Practices

Abstract: Potatoes grown under furrow irrigation sustained over 58 times greater infestation by Phthorimaea operculella (Zeller) and 3 times more green tubers than potatoes grown under sprinkler irrigation even though foliage tuberworm populations, soil type, and soil moisture levels were similar. Water usage on a per ha basis was more efficient under sprinkler irrigation. Under furrow irrigation, hilling the rows 4 times significantly reduced the percentages of greenheads, infested whites, and total infestation over those rows hilled twice. The method of vine removal affected the level of tuber infestation in rows hilled twice but not in rows hilled 4 times. Under frequent sprinkler irrigation potato tuberworm damage was low and not significantly affected by cultural practices. Soil cracking was more extensive under furrow than under sprinkler irrigation, and infestation was significantly correlated with the depth of soil cracks regardless of hilling practices.

Effects of Planting Date and Soil Water on Infestation of Sunflower by Larvae of Cylindrocopturus adspersus

Abstract: Plant population had no significant effect on the infesation level of Cylindrocopturus adspersus (LeConte) larvae infesting the stalks of cultivated sunflower under dryland conditions. However, the mean number of larvae per plant was significantly (5% level) reduced by both delayed planting dates and reduced preplant soil water. Delayed planting dates also significantly reduced the avg number of larvae per plant and percentage infestation in irrigated sunflower. Application of insecticide to control adults reduced the number of larvae infesting stalks of irrigated sunflower, reduced plant lodging, and resulted in significant (5% level) increases in both the quantity and the quality of seeds produced in plants that did not lodge.

Human infestation by cat fleas, Ctenocephalides felis (Siphonaptera: Pulicidae), from suburban raccoons.

Abstract: A case of human infestation by cat fleas ( Ctenocephalides felis ) from suburban Raccoons is reported. The infestation, which resulted from the rapid departure of host Raccoons living in close association with a human habitation led to a severe case of flea-bite dermatitis in a young woman. The public health impact of this and similar human-wild mammalectoparasite associations is discussed.

Intestinal parasitic infestation in urban and rural Xhosa children. A comparative study.

Abstract: Evidence of helminthic intestinal parasites was found in 97,0% of stools of 544 Xhosa schoolchildren living in Cape Town. The commonest parasite was Trichuris trichiura, which infested 89,9% of the children. In contrast, only 9,8% of 387 Xhosa children living in the Tsolo district, Transkei, had evidence of intestinal parasites in their stools, Hymenolepis nana being the commonest. In spite of the unsatisfactory sanitary conditions in the Tsolo area compared with those in Guguletu, Cape Town, where all sewage is waterborne, few rural children were infested. The high prevalence of infestation in the Guguletu children suggests extensive contamination of the soil in the area by parasitic ova. In view of the magnitude of the extent of parasitic infestation in the Guguletu children, a vigorous and sustained programme of medication and education will have to be undertaken if the problem is to be resolved.

Selection for resistance to potato leafhopper in potatoes. II. Progress after two cycles of phenotypic recurrent selection.

Abstract: ASolatium tuberosum L. gp.tuberosum population was subjected to 2 cycles of phenotypic recurrent selection for resistance to the potato leafhopper,Empoasca fabae (Harris), as expressed by low levels of nymph infestation. Samples of lines from the original population and from the cycle 2 population were tested for infestation levels at 2 locations for 2 years. Infestation in cycle 2 lines was 54% lower than that in lines from the original, unselected population.

Yield reduction caused by the lesser cornstalk borer in nonirrigated Spanish peanuts.

Abstract: Serial dosages of carbofuran and chlorpyrifos were utilized to obtain a gradation of infestation levels of Elasmopalpus lignosellus (Zeller) in nonirrigated ‘Spanhoma’ variety peanuts. A highly significant (P < 0.001) linear relationship existed between infestation levels and yield of peanuts. For each increase of 1% in infested plants, yield reduction equaled 9.87 kg/ha.

A New Technique for the Diagnosis of Acarine Infestation in Honeybees

Abstract: SummaryA new technique for the diagnosis of acarine infestation of honeybees consists of grinding the thorax, and centrifuging and examining the deposit. It proved to be both sensitive and quantitative, and can be rapid, even with large samples of bees. Some of the results obtained with it are discussed in relation to the pathogenicity of the mite to the honeybee.

Artificial Infestation of the Tomato with Eggs of the Tomato Fruitworm

Abstract: Field-grown tomatoes were artificially infested with Heliothis zea (Boddie) by applying a suspension of eggs in a 0.2% agar solution to the top surface of randomly located leaves. The degree of infestation depended largely upon the number of eggs applied. Fruit damage due to natural H. zea populations ranged from 6 to 10% and that due to the natural populations plus the maximal numbers of eggs tested, 3000–3200 eggs/plant, ranged from 51 to 54%. There was a curvilinear relationship between number of eggs and degree of fruit damage; damage increased as egg dosage increased but at a decreasing rate. Application of eggs was most effective ca. 1 mo before 1st harvest. Multiple or repeated applications were no more efficient than a single application of an equivalent number of eggs. Practical aspects of the choice of an appropriate damage rating criterion are discussed. The method seems satisfactory for use in screening tomatoes for resistance to H. zea .

Effect of infestation stage, form and treatment on fragment count in flour

Abstract: 44

The Pickleworm: Laboratory Rearing and Artificial Infestation of Cucumhers

Abstract: A procedure was developed for rearing Diaphania nitidalis (Stoll) in the laboratory and for establishing artificial infestations on cucumber plants. From 24 to 57% of the larvae survived when they were placed on the growing tips of ‘Addis’ cucumber plants inside a screenhouse; 29–57% of those were recovered from the fruit. A system of visually rating plant damage from 1 to 5 (5 = heavily damaged) was developed for use in screening cucumber lines for resistance to pickleworm damage. The correlation coefficient between infestation levels and plant damage ratings for all plants tested was 0.783 ( P =0.01). About 120 larvae/plant were required to produce a damage rating of 4 on mature Addis cucumber plants.

Aggregated distribution of Ditylenchus dipsaci on broad bean seeds

Abstract: SUMMARY The distribution of Ditylenchus dipsaci (Kuhn) Filipjev between seeds in infested samples of broad bean seed was skewed so that the nematodes were concentrated on a few seeds. Such aggregation increases the likelihood of reproduction by the nematodes in infested plants and the consequent establishment of foci of infestation in the soil. These foci will be small and scattered giving the nematode the best chance of a finding a favourable environment in the field. The numbers of foci of infestation introduced by seed tend to be nearly constant, independent of the numbers of nematodes on the seed and therefore provide a stable unit of population.

Tokelau Islands Children's Study: scabies infestation in children.

Abstract: Tokelau children have been examined for scabies infestation in three groups--those living in their home atolls--those living in New Zealand in 1972-73, and those living in New Zealand in 1975. There was less infestation in Tokelau than in New Zealand. In 1975 the rate of infestation in New Zealand had increased since 1972. The manifestation of the mite in children in New Zealand varied from the classical descriptions, in that the mite itself, and its burrows, were seldom found, and the skin lesions were more often seen on the body than on the wrists and hands. A treatment regime which was found satisfactory is described. It was found essential to treat the entire family at the same time.

Effects of some factors on the susceptibility of Peromyscus leucopus to infestation by larvae of cuterebra fontinella (Diptera: Cuterebridae).

Abstract: Two levels of 3 factors, (1) host age, (2) host dietary state in regard to vitamin A, and (3) previous infestation history, were tested individually and in combinations for their effects on the susceptibility of Peromyscus leucopus to infestation by larvae of the rodent bot fly, Cuterebra fontinella. Previous infestation was the only significant single factor. Previously uninfested (Pu) mice usually were more susceptible to infestation than previously infested (Pi) mice. Interactions of age and state of vitamin A had the following effects: 1) Young Pu mice that had been denied vitamin A were much less susceptible to infestation than equivalent mice that had been fed diets containing the vitamin; and 2) when Pu mice were deficient in vitamin A, old mice were more suscep- tible than young mice but when Pu mice were not deficient in the vitamin, young mice were more susceptible. These findings may have significance for natural infestations of P. leucopus.

Biology and infestation rate of Corallonoxia longicauda, an endoparasitic copepod of the West Indian reef coral Meandrina meandrites

Abstract: During 1½ year the biology of Corallonoxia longicauda, a copepod endoparasitic in the stony coral Meandrina meandrites was studied in Curacao, Netherlands Antilles. The infestation rate of the corals as well as the numbers of parasites present were investigated at several depths and in several stations. The parasites proved to be distributed in a spatial pattern inside the colony. This pattern appeared to be correlated with current and exposure. It is postulated that the numerical distribution of the copepods in the corals, which differs markedly from a normal distribution, depends on the way of proliferation and settling of the parasites. This offers also an explanation for the remarkable spatial pattern inside the colony. The results of the comparison of the biomasses of host and parasite indicate that the parasite must be rather harmless to its host, and that no significant influence of its metabolism on the skeleton formation of the coral is to be expected.

Method of reducing infestation of citrus rust mites on citrus trees

Abstract: A method of reducing the population of the citrus rust mite on citrus trees by treating the trees with such substituted benzoyl phenyl ureas as N-(2,6-difluorobenzoyl)-N'-(3-fluoro-4-chloro-phenyl) urea and N-(2,6-difluorobenzoyl)-N'-(4-chloro-phenyl) urea.

Characteristics of spruce beetle (coleoptera) infestation in felled white spruce in alaska

Abstract: The antiaggregation pheroraone MCH was ineffective in preventing spruce beetle infestation in felled spruce near Hope, Alaska. In October, most progeny were larvae but some were pupae and new adults. Densities of spruce beetle attacks and progeny on the shaded under side of stems were about twice those on the upper side, whereas attacks of Polygraphus rufipennis (Kirby) and Dryocoetes affaber (Mann.) on the upper side were 100 times those on the under side. Ips tridens engelmanni Swain was present in only 2% of bark samples. Entomophagous insects were scarce; only Medetera sp. and Coeloides sp. were found. Spruce beetle progeny were 45 times more abundant than attacking parents. Factors affecting the efficiency of sampling spruce beetle attacks and progeny are discussed.

Sunflower Bud Moth: Behavior and Impact of the Larva On Sunflower Seed Production In the Southern Plains

Abstract: Peak infestation of sunflower, Helianthus annuus L. by larvae of the sunflower bud moth, Suleima helianthana (Riley), averaged 12.7% in mid-May-planted plots and 3.7% in mid-July-planted plots at Chillicothe (1975–1976) and Bushland (1976–1977), Texas, respectively. Peak infestation at Chillicothe occurred in late July, and at Bushland in late June and late Aug. From 63.4–85.3% of 1st-generation larvae were found in the stalks, whereas ca. 60% of the 2nd-generation larvae were found in the receptacles. Most infested plants harbored a single larva. The only infestations that caused a significant loss of seed were those that occurred in either the terminal of small plants or in receptacles of less than 5 cm diam. New host records are given for S. helianthana on 17 species of Helianthus .

The influence of the lucerne bud mite (Eriophyes medicaginis Keifer) on the growth of annual and perennial Trifolium species.

Abstract: Studies were made of the influence of E. medicaginis on the growth of 11 wild or cultivated lines of perennial Medicago, embracing seven species, and one cultivar of each of the annual species M. littoralis and M. truncatula. Mite infestation of the perennial species caused significant (P < 0.05) reduction in shoot dry weight of six of the 11 lines. It did not significantly influence leaf number and generally did not reduce stem length. However, it caused significant (P < 0.05) reduction in petiole length in most of the lines. Mite infestation of annual species caused highly significant (P < 0.01) reductions in shoot dry weight and produced leaf symptoms similar to some of those observed on the perennial species. Mites reproduced on all species, but to a greater extent on the perennials than the annuals. There were no significant differences in either mite or egg numbers per seedling amongst the perennial species, 26 days after infestation with 10 mites per seedling. The occurrence of symptomless plants bearing high mite numbers amongst the perennial species, M. coerulea, M. falcata, M. glutinosa, M. hemicycla and M. quasifalcata, suggested the presence of physiological tolerance to the mite within these species.

A previously unrecorded feeding site on cattle for the immature stages of the spinose ear tick, Otobius megnini (Dugès, 1844).

Abstract: During the rainy season in the central valley of Cochahbamba, Bolivia, the larvae and nymphae of this tick were found feeding under the tails of dairy cattle as well as in their ears. The conditions that apparently favour the temporary infestation of this site on some cows are discussed briefly.

Prospettive di lotta integrata nell'agrumicoltura sarda

Abstract: Preliminary integrated control trials were performed in two fruit growing areas of Sardinia (Simaxis, Siniscola) in 1979. On the orange groves of Simaxis Planococcus citri (Risso) is the most important phytophage, followed by Panonychus citri Mc Gr. and Dialeurodes citri (Ashm.). The indigenous natural enemies of Planococcus {Anagyrus pseudococci Grlt., Leptomastidea abnormis Grlt., Chrysopa sp., Chilocorus bipustulatus (L.)) and Panonychus ( Stethorus punctillum Weiss, Amblyseius stipulatus A.H.) do not occur in sufficient number to limit infestation and it is therefore necessary to use chemical control with 2 treatments of white oil + methidathion and an acaricide (chlorfenson + propargil). This treatment has also contained infestation of Dialeurocles which is also actively preyed by Clitostethus arcuatus (Rossi). Cryptolaemus montrouzieri Muls., Leptomastix dactylopii (How.) and Prospaltella lahorensis (How.) were introduced to improve the biological control of Plalnococcus and Dialeurodes . Ceratitis capitata is the most important phytophage or the clementine crop in Siniscola. Populations are monitoring with withe traps baited with trimedlure and reached a maximum of 150 males/trap/weck at the end or October. Three treatments with hait-spray (protein hydrolysate + Fenthion) proved insufficient to contain the infestation due to rain in September and October. In November, although 40% or fruits were punctured, only 2% contained live larvae. Heavy aphid infestations (particularly Aplzis citricola V.d.G.) were recorded in June on around 50% of the shoots. One treatment with sclective aphicides stopped the infestation without influencing beneficial predators (mainly Coccinellids). For the orange cultures in Siniscola, bait-spray applications limited damage by Ceratitis and no action was necessary against aphids, since infestations were small and the plants had low susceptibility. On the basis or these observations, for the different phytophages are proposed some sample methodologics and the relative intervention thresholds .