Showing papers on "Infestation published in 1990"

Host Plants of Mediterranean Fruit Fly (Diptera: Tephritidae) on the Island of Hawaii (1949-1985 Survey)

Abstract: Extensive fruit collections were done between 1949 and 1985 on the island of Hawaii to determine the infestation biology of Mediterranean fruit fly, Ceratitis capitata (Wiedemann), in different fruit-bearing plants. The data base developed from this survey consists of 13,423 records (collections) with a total of 953,660 fruits collected. Of the 196 fruit species collected, 60 are Mediterranean fruit fly hosts under natural field conditions. The suitability of fruit species as Mediterranean fruit fly hosts was determined based on number of emerged adults per kg of infested fruits and percentage collections infested. At present, Jerusalem cherry, Solanum pseudocapsicum L., and coffee, Coffea Arabica L., are the two most important hosts of Mediterranean fruit fly on the island of Hawaii. We provide the first documented infestation data for 12 plant species that have long been recognized as potential hosts of Mediterranean fruit fly. We compare our results with previous and concurrent surveys conducted in the state of Hawaii and with published world host records. Finally, we examine the definition of a suitable host in the context of regulatory entomology and its relevance in understanding the infestation biology of Mediterranean fruit fly.

Relationship of the sweetpotato whitefly to a new tomato fruit disorder in Florida

Abstract: A new disorder of fruit has been observed on tomato (Lycopersicon escu- lentum Mill.) in Florida. The disorder, termed irregular ripening, was associated with field populations of the sweetpotato whitefly, Bemisia tabaci (Gennadius) and is char- acterized by incomplete ripening of longitudinal sections of fruit. An increase in internal white tissue also was associated with whitefly populations. In field cage studies, fruit on tomato plants not infested with the sweetpotato whitefly exhibited slight or no irregular ripening, whereas fruit from infested plants did. Fruit from plants on which a whitefly infestation had been controlled before the appearance of external symptoms exhibited reduced symptoms compared to fruit from plants on which an infestation was uncontrolled.

Epidemiological studies on head lice infestation in Israel. I. Parasitological examination of children.

Abstract: Of 3,079 children in a medium-sized community near Jerusalem, 11.2% were found to be infested with living lice and eggs and another 23.4% had only nits. Boys and girls were equally infested. The incidence of infestation was highest among children4–11 years of age. About 78% of the infested children had from one to ten lice. Approximately 80% of the infested children had nits that were 2–5cm away from the scalp. Boys with medium length hair and girls with short hair showed the highest incidence of lice infestation. Children with brown and red hair were more infested than those with black and blond hair. Boys and girls with straight and wavy hair were more infested than those with curly and frizzy hair.

Frequency and ecological correlates of parasitism by conopid flies (Conopidae, Diptera) in populations of bumblebees.

Abstract: We present field data on the ecology of a host-parasite system, consisting of several species of parasitoid flies (Conopidae, Diptera) and their bumblebee hosts (Bombini, Apoidea, Hymenoptera). Host animals were systematically sampled from different study sites throughout a season and checked for successful infestation in the form of puparia of these endoparasitic flies. Such dissection of the bees revealed that infestation occurs primarily during the summer months (June to September), with an observed maximum frequency of parasitization of 46.7% in workers in one of our study sites. On average, 13.2% of all workers (range 0–46.7%) and 7.1% of all males (range 0–28.6%) contained the puparium of a conopid. Two conopid generaSicus (64% of cases) andPhysocephala (36%) accounted for the infestation, with the latter being more abundant later in the year. A multivariate analysis identified host species, sex (male or worker), and study area as the most important factors accounting for the observed variance in the probability of being parasitized during the summer months. On average, males were less affected than workers. The marked seasonal appearance of conopids seems to account for differences among species, in particular for low levels of infestation among species completing their life cycles early (e.g.B. pratorum) and among the early flying, hibernated quens ofBombus andPsithyrus species. The results are discussd with respect to the impact of conopids on host ecology and evolution. Additional observations on the occurrence of further endoparasites (Sphaerularia bombi andSyntretus sp.) are reported.

Relationship between Fruit Phenology and Infestation by the Apple Maggot (Diptera: Tephritidae) in Utah

Abstract: The apple maggot, Rhagoletis pomonella (Walsh), occurs commonly in black hawthorn in Utah, attacks tart cherry infrequently, and has generally failed to infest apples. This study investigated how the timing of fruit maturation might account for this pattern. Infestation of hawthorn at three sites in 1988 commenced when fruits were rapidly increasing in size and water content, and perhaps most significantly, when mean resistance to penetration of the fruit skin dropped below a threshold. Dissections of trapped females indicated that a significant fraction of flies possessed mature ovaries before oviposition occurred in hawthorn in the field. The importance of fruit toughness early in the season also was suggested by measurement of individual fruits in 1989; no fruit with a penetration resistance >60 kg/cm2 yielded a fly puparium. No puparia were obtained from three apple cultivars that were sampled from an unsprayed orchard adjacent to a densely infested hawthorn stand. When apples collected during the oviposition period in hawthorn were presented to caged flies, only the early-maturing cultivar was successfully infested. Penetration resistance of mid- and late-season cultivars remained high throughout the period of fly activity. These results suggest that flies that originate in hawthorn in Utah emerge too early to attack the dominant local cultivars of apple. In contrast, the timing of adult emergence is relatively late for infestation of cherry, which ripens well before hawthorn. In behavioral assays, fruit phenology had only a minor effect on fruit acceptance; ovipositing females were less likely to attempt oviposition in immature hawthorn or cherry fruits but failed to discriminate between nearly ripe and ripe fruits.

Variance and heritability of the capped developmental stage in European Apis mellifera L. and its correlation with increased Varroa jacobsoni Oud. infestation.

Abstract: SummaryA time-saving method for determining the duration of the capped stage (sealed brood) of large numbers of colonies is described. The results of 112 colonies covering 22 different origins and hybrids of European honeybee races are presented. Differences up to 9 h between strains and up to 19 h within individual colonies could be detected. Influenced by seasonal effects, the average capped period is about 7 h shorter in early than in late summer. For one group of test colonies (n= 21) the Varroa infestation after 18 months of undisturbed colony and mite population development has been determined. The correlation between the capped period and the susceptibility of the colonies to mites is calculated as r = 0·48. By linear regression, an 8·7% reduction of the final mite infestation is calculated for a 1-h reduction of the capped period. The heritability of the duration of the capped period is estimated with h2 = 0·232. This may be a realistic value for test populations of European honeybee under field c...

Patterns of Abies fraseri regeneration in a Great Smoky Mountains spruce-fir forest

Abstract: PAULEY, E. F. AND E. E. C. CLEBSCH (Graduate Program in Ecology, University of Tennessee, Knoxville, TN 37996-1610. Pattems of Abiesfraseri regeneration in a Great Smoky Mountains spruce-fir forest. Bull. Torrey Bot. Club 117: 375-381. 1990.-Abiesfraseri (Pursh) Poir. (Fraser fir) has incurred high mortality from infestation by Adelgespiceae Ratz. (balsam woolly adelgid). Vegetational changes in the spruce-fir forest since Adelges infestation have included a large increase in the density of Rubus canadensis L. (thomless blackberry). Size and age structures, microsite and aspect distributions, and growth of Abies seedlings (stems < 137 cm tall) were quantified on Mt. Collins, Great Smoky Mountains National Park in 1988 to determine pattems of co-occurrence between Abies seedlings and Rubus. The majority (87%) of seedlings were c25 cm tall, and most (62%) were at least five years old. No germinal (< 1 year old) Abies were found. Dead wood substrates and bryophyte-covered surfaces both supported more seedlings than expected by chance. Seedling growth trends showed a recent increase in terminal shoot length and recent decreases in lateral shoot lengths, suggesting a combination of normal growth pattems and recovery from Adelges infestation. Effects of Adelges infestation were noted for 26% of all seedlings and were more frequent among older seedlings. Density of Abies seedlings was low at high Rubus densities, but seedling shoot growth showed no clear relationship with Rubus density. Rubus appeared to interfere with establishment or survival of Abies seedlings but not with annual growth.

The effect of host resistance to tick infestation on the transmission of Thogoto virus by ticks.

Abstract: Tick-borne virus transmission was examined using guinea-pigs and hamsters previously infested with ticks. Guinea-pigs developed immunity to Rhipicephalus appendiculatus after a single exposure to the ticks. Nymphal and adult stages that fed on resistant guinea-pigs had increased mortality during feeding, and reduced engorged weights. Egg production from female ticks fed on resistant hosts fell by at least 50%. Guinea-pigs maintained high levels of immunity to tick infestation for at least 210 days after the initial exposure. In contrast, hamsters did not develop resistance to ticks even after three or four infestations. R. appendiculatus adults infected with Thogoto (THO) virus (donors) were allowed to co-feed with uninfected nymphs (recipients) on either resistant or naive guinea-pigs. The number of recipient ticks that acquired virus was significantly reduced on resistant guinea-pigs. In contrast, feeding on pre-infested hamsters did not affect tick-borne transmission of THO virus. Host resistance to tick infestation, if prevalent in nature, may severely limit the spread of tick-borne viruses. Such an effect could result directly from a reduction in the number of ticks that acquire virus, or indirectly from poor egg production (in the case of viruses maintained in ticks by vertical transmission) and reduced survival of ticks fed on resistant hosts.

Infestation Patterns of Commonly Cultivated., Edible Fruit Species by Ceratitis capitata and Anastrepha spp. (Diptera: Tephritidae) in Guatemala and Their Relationship to Environmental Factors

Abstract: In Guatemala, 1,137 fruit samples weighing 3,912 kg from 30 host plants had a mean C. capitata infestation of 1.58 (range, 0.1–382.9) pupae/kg and 20.18 (range, 0.1–447) for Anastrepha spp. from 1980 to 1983. A. ludens was the most abundant and was found from 10 to 2,000 m elevation. Ranking of host fruits revealed that C. capitata infested mostly introduced temperate zone fruits and Anastrepha spp. mostly the tropical fruits. Infestation was inversely correlated with the numbers of mature fruits available on the trees and positively correlated with altitude up to 2,000 m for C. capitata and A. ludens , as well as with host plant biomass for C. capitata . An infestation sequence showed the preference of C. capitata for the fruits present in the field. Diversity of host plant infestation of Anastrepha in different regions of South and Central America and the economic importance of both genera in Guatemala are discussed.

Immunization of guinea-pigs against Rhipicephalus appendiculatus adult ticks using homogenates from unfed immature ticks

Abstract: Guinea-pigs immunized with homogenates of unfed larvae and nymphs of the tick Rhipicephalus appendiculatus developed significant levels of protective immunity to infestation with adults of this species. The mean engorged weight of female ticks feeding on immunized animals (181.96 +/- 05.63 mg and 170.11 +/- 11.54 mg) was reduced by an average of 46% and 51%, respectively, compared to that of female ticks feeding on control guinea-pigs, although in some individual animals the reduction was as high as 86%; the mean egg mass weight was also significantly reduced. Electrophoretic separation of the homogenates followed by immunostaining with post-infestation sera revealed several antigen bands common to all stages. Two bands of 36,500 and 23,000 molecular weight (MW) were recognized in all homogenates by post-adult infestation serum, but not by post-larval or post-nymphal infestation sera, suggesting that these may be antigens specifically involved in feeding by adult ticks, and are either not presented to the host's immune system or presented only in minimal amounts during feeding by immature stages. Sera from animals immunized with the homogenates did not recognize either of these antigens. Post-immunization sera did, however, stain two bands of 84,000 and 60,000 MW in the homogenates which were not recognized by post-infestation sera.

Biological control sought for ash whitefly

Abstract: Ash whitefly has spread over a large portion of California since the initial infestation was discovered in Los Angeles County in 1988. Populations have grown to high densities on a wide range of host plants, including ash, pear, apple, citrus, and other landscape and fruit trees. The best hope for control appears to be natural enemies: a parasitic wasp and a predatory beetle have been introduced and are being evaluated.

Cattle lice (Anoplura, Mallophaga) in New York: seasonal population changes, effects of housing type on infestations of calves, and sampling efficiency.

Abstract: A year-long survey was made of commercial dairy herds in New York for cattle lice (Anoplura and Mallophaga) All herds were infested with lice The cattle bitting louse, Bovicola bovis (L), accounted for about 90% of the observed infestations; infestations of mature animals were most common during the winter months, especially March (26% infested); and infestation rates of calves were high (30-45%) from January through June Cows that were housed in stanchion barns were about twice as likely to be infested (247%) as were those in free stalls (111%) Calves housed in individual outdoor hutches had substantially lower infestation rates (45%) than calves maintained inside barns in collective stalls and pens (460%)

Feeding of Hessian fly (Diptera: Cecidomyiidae) larvae on resistant and susceptible wheat.

Abstract: The duration of feeding and relative amounts consumed by Hessian fly, Mayetiola destructor (Say), larvae on resistant and susceptible seedling wheat plants labeled with [35S]L-methionine was investigated. Plants were labeled over 48-h periods from initial infestation to 8 d after infestation, and the uptake of 35S by larvae determined. With the H3 and H5 genes for resistance, the uptake of 35S by larvae was significantly less than on susceptible controls, and suggested that the larvae were unable to initiate or maintain sustained feeding on the resistant plants. With the H6 gene for resistance, uptake of 35S by larvae during the first 48 h was not significantly different from that on susceptible controls, but then declined between 48 and 96 h. These data indicate that with the H6 gene, larvae fed actively for the first 48 h after infesting the plants, then ceased their feeding between 48 and 96 h. All larvae on resistant plants were alive 48 h after infesting plants and approximately 60% were alive 96 h after infesting resistant plants. All larvae on resistant plants were dead by 144 h after infestation. Results are discussed in the context of possible mechanisms of action for the resistance genes investigated.

Damage to cowpea by the legume pod borer, Maruca testulalis Geyer, as influenced by infestation density in Nigeria

Abstract: In experiments at Makurdi, Nigeria, to quantify the damage to cowpea by different densities of the legume pod borer (LPB), Maruca testulalis cypermethrin 10 EC was sprayed at 0.2 kg/ha a.i. to control larvae when its infestation in flowers reached 10, 20, 30, 40 and 50% in 1985 and 10, 20 and 30% in 1986. Larval damage to the flowers and pods increased with the percentage infestation and reduced the yield to 72.1% in 1985 and 48.1% in 1986. A provisional action threshold of 40% larval infestation in flowers was established, based on the increased damage caused by this level of infestation in flowers and pods and the reduction in yield compared with a > 10% pre‐spray infestation.

Immunity of the ox to the brown ear tick Rhipicephalus appendiculatus.

Abstract: Controlled repeated infestation ofBos taurus andBos indicus cattle resulted in a decline in the recovery of allR appendiculatus instars Resistance to infestation varied between individuals although all individuals manifested severe hypersensitivity at the attachment site, which was reflected in the grooming reflex

Antagonists of Plant-parasitic Nematodes in Florida Citrus.

Abstract: In a survey of antagonists of nematodes in 27 citrus groves, each with a history of Tylenchulus semipenetrans infestation, and 17 noncitrus habitats in Florida, approximately 24 species of microbial antagonists capable of attacking vermiform stages of Radopholus citrophilus were recovered. Eleven of these microbes and a species of Pasteuria also were observed attacking vermiform stages of T. semipenetrans. Verticillium chlamydosporium, Paecilomyces lilacinus, P. marquandii, Streptomyces sp., Arthrobotrys oligospora, and Dactylella ellipsospora were found infecting T. semipenetrans egg masses. Two species of nematophagous amoebae, five species of predatory nematodes, and 29 species of nematophagous arthropods also were detected. Nematode-trapping fungi and nematophagous arthropods were common inhabitants of citrus groves with a history of citrus nematode infestation; however, obligate parasites of nematodes were rare. Key words: biological control, burrowing nematode, citrus nematode, nematophagous arthropod, nematophagous fungus, Pasteuria, Streptomyces.

Reduction of Insect Infestation and Fungal Infection by Cultural Practice in Date Gardens

Abstract: ‘Deglet Noor’ date gardens were subjected to various degrees of sanitation of damaged dates to observe effects on infestation of a carob moth, Ectomyelois ceratoniae (Zeller), raisin moth, Cadra figulilella (Gregson), four species of nitidulid beetles, and fungal infection. In a year of above average rainfall, 1984, infestation by carob math, raisin moth, and nitidulid beetles was significantly reduced at harvest ( P < 0.05) in areas sanitized by the weekly removal of damaged dates from the ground. Fallen dates consisted of “Junedrop” and khalal stage dates, many of which had been infected by fungi (chiefly Aspergillus and Alternaria spp.) as a result of rain. These provided a substrate conducive for the buildup of insect populations in July and August. However, in a year of no summer rainfall and above-average summer temperatures (1985), June-drop dates became completely desiccated in the palms and on the ground, and fungal infection of khalal stage dates was inhibited. Consequently, populations of E. ceratoniae , raisin moth, and nitidulid beetle were greatly suppressed by the lack of suitable substrates and no benefit by sanitation was indicated.

Infestation levels of dogwood borer (Lepidoptera: Sesiidae) larvae on dogwood trees in selected habitats in Tennessee.

Abstract: Infestation levels of dogwood borer [Synanthedon scitula (Harris)] on flowering dogwood (Cornus florida L.) in commercial nursery, urban, and forest habitats in eastern and middle Tennessee were measured during 1987 and 1988. The highest average infestation level (ca. 60%) was found in the urban habitat, where mechanical injury, e.g., damage caused by lawn mowers or string trimmers, may have provided oviposition or larval entry sites. Dogwood borer larvae were found in all nursery blocks examined, with ca. 7% of the trees infested/block. Infested trees are not marketable; thus, economic losses averaged ca. $l,800/block (x = 1,770 trees/block) of dogwoods. Infestation levels were lowest (ca. 1%) in the forest habitat, where dogwoods grow as a natural component of the forest understory.

Growth Reduction in Nonbearing Apple Trees by Woolly Apple Aphids (Homoptera: Aphididae) on Roots

Abstract: The effect of root-feeding populations of woolly apple aphids, Eriosoma lanigerum (Hausmann), on newly planted, nonbearing apple trees in an orchard environment was studied. Roots of two-thirds of the 351 ‘Red Delicious’ study trees were artificially infested with woolly apple aphids from a laboratory colony in 1986, 1 mo after planting. The artificial infestation resulted in 95% of the trees being infested (including controls), but did not produce more severe root infestations per tree than expected in natural infestations. The root infestation rating (mean = 0.35 on a scale of 0-1, SEM = 0.18) determined from destructive sampling of one-third of the orchard after three growing seasons was not correlated with population density above ground throughout the 3 yr of the study. Root feeding marginally reduced branch growth in the first and third year after infestation, crown length in the third year, and trunk diameter in the first and second years. Crown length was significantly reduced after 1 yr and trunk diameter was significantly reduced after 3 yr because of woolly apple aphid feeding on roots. Scion biomass also was significantly reduced by woolly apple aphid root feeding after 3 yr. We conclude that woolly apple aphid populations on roots have a slight, but significant, negative effect on growth of young non bearing apple trees in the orchard environment. We also conclude that, because of the lack of correlation between woolly apple aphid populations aboveground and on roots, sampling branch terminals and pruning scars yields no information on the density of woolly apple aphids on roots.

2.0 mass-production of trichogramma minutum riley on factitious host eggs

Abstract: A system was developed to produce large numbers (30 × 106 per week) of Trichogramma minutum Riley on eggs of the Angoumois grain moth, Sitotroga cerealella (Olivier). The parasitized host eggs were packaged and shipped in bulk for release against the spruce budworm, Choristoneura fumiferana (Clemens), and several other lepidopterous pests. Initial attempts to use the Mediterranean flour moth, Ephestia kuehniella (Zeller), as a host failed due to such factors as infestation by mites and parasitoids, low fecundity, long generation time, and the necessity for large labour inputs during moth collection. Eggs of S. cerealella, used to rear the host, remained viable when stored for up to 1 month at 9 °C, but eggs stored at 2 °C remained acceptable for parasitism for only 15 days. Rearing the host at high humidity (> 70% RH) gave better percentage emergence and infestation of grain than rearing at low humidity (< 30% RH). Developmental rates of T. minutum were determined over a range of temperatures and the developmental threshold and heat unit accumulations necessary for complete development were calculated. Using these values, Trichogramma were programmed, during the latter stages of production, to emerge within 24 h of exposure to light at room temperature. The programming facilitated shipment and handling of the parasitoids prior to their release.

Weekly Economic Injury Levels for Fall Armyworm (Lepidoptera: Noctuidae) Infestation of Corn in Lowland Ecuador

Abstract: Fall armyworm, Spodoptera frugiperda (J. E. Smith), was controlled at weekly intervals in corn on Ecuador's coastal plain to determine the effect of plant stage on yield loss from pest injury. Greatest yield increases due to insecticide treatments occurred when plants were infested in the second week after germination; yields progressively decreased through tasseling. Economic injury levels calculated from a regression of these data increased from 11% to 42% infestation during the first 6 wk following plant emergence. Spray decisions based on economic injury levels linked to crop maturity could result in lower control costs than presently achieved with fixed economic injury levels.

Tolerance of wheat to Russian wheat aphids: Nitrogen fertilization reduces yield loss

Abstract: The influence of nitrogen nutrition and Russian wheat aphid (Diuraphis noxia Mordvilko) infestation on morphology and grain yield of wheat (Triticum aestivum L.) was studied in growth chamber experiments. Plants were grown with nutrient solution containing 100, 50, 10, or 0 percent of the normal complement of nitrogen. Plants were infested with eight apterous adult Russian wheat aphids at the flag leaf stage (approximately 53 days after planting). The aphids remained on the plant for a period of 25 days. Aphid infestation reduced mature plant height across all nutrient solution nitrogen concentrations tested. Grain yield was reduced by aphid infestation under all nutrient solution nitrogen concentrations except 0 percent. However, the percentage of yield loss caused by aphid infestation was reduced by increased levels of nitrogen in the nutrient solution. These results suggest that nitrogen fertilization might be a useful strategy for limiting yield loss caused by Russian wheat aphid in plants th...

Assessing the risk of primary infection of cereals by barley yellow dwarf virus in autumn in the Rennes basin of France

Abstract: SUMMARY In the Rennes basin, Rhopalosiphum padi is anholocyclic and represents more than 90% of suction trap catches of potential vectors of barley yellow dwarf virus (BYDV) during autumn From 1983 to 1987 the possibility of predicting the risk of BYDV infection of batches of barley test seedlings (sampling units) exposed each week from September to December near a 122 m high suction trap was investigated Three kinds of variables were checked as possible predictors: weekly mean or maximum temperatures; weekly catches of R padi (including or excluding males); and percentage of sampling units infested by aphids Three contrasting examples were observed: during the first three years (1983–1985), infection was high and its change with time followed temperature, aphid catches and plant infestation changes; in 1986, high numbers of aphids caught and a high proportion of plants infested resulted in only low infection and in 1987, both infestation and infection were very low Simple linear regression analysis showed that the more reliable predictors of infection were the proportion of infested plants and to a lesser extent the numbers of trapped aphids Multiple linear regressions including either of the three groups of ‘predicting’ variables did not result in any improvement in the prediction At a practical level, the use of counts of aphid catches would seem a better compromise between accuracy and consistency of prediction and ease of gathering data than that of plant infestation but any significant improvement of the prediction should be sought in an early estimate of the amount of virus available to aphids before they colonise the plants

Rabbit antibody responses to experimental infestation with Dermatobia hominis

Abstract: The three larval stages of Dermatobia hominis (Linnaeus) have been evaluated for their immunogenicity by ELISA and immunodiffusion (ID) using sera from experimentally infested rabbits. During a primary infestation, first instar D. hominis were found to cause most reaction and allowed the earliest diagnosis by ELISA. An inhibition of the antibody response against second and third instars was observed. The inhibition disappeared after departure of the larvae from the host. In experimentally immunized hosts the antibody response, following challenge, was highest against second and third instar antigens. Antibody remained elevated during the infestation but fell immediately after the larvae had left the host.