Showing papers on "Infestation published in 1989"

Geographic Variation in Effects of Weather on Grasshopper Infestation

Abstract: Effects of weather on infestation levels of grasshopper assemblages in the shortgrass prairie regions of Montana, Wyoming, Colorado, and New Mexico were examined using correlation and multiple regression analyses. Fifty-three years of population and monthly weather data were analyzed to estimate the effects of temperature, precipitation, and a heat/precipitation (H/P) drought index on extent of infestation of grasshoppers. Regressions and correlations indicated that effects of weather varied with latitude. Infestation levels in both northern states (Montana and Wyoming) were positively associated with 3-yr mean July-August temperatures. Significant terms in regressions for the southern states (Colorado and New Mexico) were spring and summer H/P ratios; infestation was negatively associated with H/P. These results suggest that grasshoppers in more northern states are favored by warm, dry summer conditions, whereas grasshoppers of southern areas appear to require spring and summer moisture. Results are compared with similar analyses done for grasshoppers in Canada and for Old World locust populations. Impact of insecticides on long term infestation trends was analyzed using 25–30 yr of grasshopper suppression program data. There was little evidence that grasshopper suppression activities interfered with our perception of weather–population relationships. Regression analyses indicated that number of hectares sprayed the previous year was significantly and negatively associated with infestation in Colorado and New Mexico.

Infestation by Cryptolestes ferrugineus (Coleoptera: Cucujidae) of newly harvested wheat stored on three Kansas farms

Abstract: The vertical distributions of Cryptolestes ferrugineus (Stephens) in newly harvested wheat, Triticum aestivum L., on three Kansas farms during the first two months of storage were studied to characterize the process of infestation. In three bins, the number of adult C. ferrugineus tended to decrease from top to bottom layers of grain. In the fourth bin, the numbers decreased from top and bottom layers to middle layers. A regression model explained 82.2% of the Variation between bins. These data suggest that most of the insect infestation occurred after the wheat was loaded into the bin instead of before or during loading and that insects then dispersed from the grain surfaces into the grain mass.

Serial effects of host infestation on egg allocation by the mediterranean fruit fly: a rule of thumb and its functional significance

Abstract: SUMMARY (1) Prior infestation of host kumquats (Fortunella japonica) with the eggs of the Mediterranean fruit fly, Ceratitis capitata, had a number of effects on the oviposition behaviour of conspecific flies under semi-field conditions. Overall, infestation markedly reduced the rate at which clutches were laid by a female searching within a host tree, a consequence of effects on three separate components of behaviour. (2) Egg infestation decreased the probability that a female (i) bored with her ovipositor after landing on a fruit and (ii) deposited a clutch once oviposition-boring was initiated, and (iii) deposited additional clutches at new sites on the fruit before leaving. (3) In addition, egg infestation decreased the duration of an oviposition (and thus probably the size of a clutch) and tended (although not significantly) to decrease the persistence with which a female foraged on fruit (expressed in terms of terminal search time (TST) and giving-up time (GUT)). Infestation had no effect on the persistence with which a female foraged within a tree (expressed in terms of TST and GUT) or on the rate at which a female landed on fruit.

Estimation of cowpea yield loss from Striga infestation

Abstract: Six cowpea varieties: IT 82E-60, KVU 69, TVX 3236, KN-1, Kaya Local and SUVITA-2, varying in plant habit and maturities were grown in Striga infested and control plots at Kamboinse, Burkina Faso, to estimate yield losses caused by the parasite. Striga infestation significantly reduced yields in all varieties, except the resistant variety SUVITA-2. Kayo Local which is photosensitive suffered maximum loss (83 %) from longer exposure to Striga infestation during vegetative growth.

Status, bioecology and management of Epilachna beetle, Epilachna vigintioctopunctata (Fab.) (Coleoptera: Coccinellidae) on potato in India: A review

Abstract: Among the major insect pests that attack potato, the Epilachna beetle, Epilachna vigintioctopunctata is very important in Asia. It is widely distributed in South and East Asia, Australia, America, and the East Indies. Commonly £ 12 stigma and E. 28 punctata, E. ocellata and Henosepilachna sparsa attack sola‐naceous plants. The peak period of infestation varies with’ the region, but the peak is in July‐August. The pest also feeds on brinjal (egg plant), tomato, tobacco, pumpkin and bitter gourd. The larvae and adults scrape the green matter from leaves and cause damage up to 80%. The morphology and biology are described. Among the various components of management, the predator reduviid bug, Rhinocoris fuscipes (Fab.) is recorded and seven larval parasites have been found, with 53–5–77–5% parasitization. Aspergillus flavus and Bacillus thuringiensis are effective against different stages of the pest. Various chemicals including plant products have been evaluated and sprays of 0–5% carbaryl + molass...

Prevalence, Habitat Selection, and Biology of Protocalliphora (Diptera: Calliphoridae) Found in Nests of Mountain and Chestnut-backed Chickadees in California

Abstract: Flies in the genus Protocalliphora are important nest parasites of chestnut-backed and mountain chickadees in El Dorado County and Modoc County, California. An undescribed Protocalliphora species was the predominant parasite at each site. Infestation rates of chickadee nests in nestboxes exceeded 95% in El Dorado County and 92% in Modoc County; a maximum of 273 larvae were recovered from a single nest. In contrast, only one of 84 chickadee nests was infested in Contra Costa County nestboxes. The Protocalliphora species studied was univoltine, and both sexes overwintered as adults. Dissections of related species suggest multiparity with a maximum ovipositional potential of 90 eggs per gonotrophic cycle. Eggs were placed in the nest material, and females readily oviposited in previously parasitized nests. Oviposition occurred only when nestlings were present and without discrimination with regard to nestling age. Duration of the egg stage was less than 48 hours. The first instar lasted 1 to 2 days, the second instar 2 to 3 days, the third instar 7 to 10 days, the prepupa 2 to 3 days, and the pupa 10 to 36 days. The undescribed Protocalliphora species was specific to cavity-nesting birds in forest habitats. The location and acceptance of potential hosts by various Protocalliphora species appear to be governed by two different sets of stimuli. Protocalliphora asiovora Shannon and Dobroscky and P. sialia Shannon and Dobroscky were attracted to, but never reared from, chickadee nests. Nest odor probably aids Protocalliphora females in nest location, but other short-range stimuli apparently determine which hosts are acceptable for oviposition. Nest infestation levels of the undescribed Protocalliphora species were not related to differences in nest site environment, but they were related to nest size. Larger nests apparently provided the larvae with refuges from probing activities of adult chickadees, allowing maximum survival in these nests. Natural enemies did not appear to play a major role in the population dynamics of this Protocalliphora species.

The relationship between sowing date, infestation and damage by the maize stalk borer, Busseola fusca (Noctuidae), on maize in Awassa, Ethiopia

Abstract: The relationship between sowing date and the maize stalk borer, Busseola fusca (Fuller) in terms of infestation rate, and crop damage was studied using ten successive sowing dates between April and July in 1985 and 1986. Different degrees of infestation by B. fusca were recorded from all sowing dates. Early sowing in April and the early part of May had significantly lower infestations of first generation larvae. Levels of infestation by second generation larvae were significantly higher on late sowing dates. High infestation by second generation larvae appeared to be connected with the high biotic potential of the moths of the first, non‐diapause generation. Second generation larvae caused crop loss ranging from 22–5 to 100% while it was only 0–22.6% due to the first generation. In conclusion, delay of sowing later than April may result in serious crop yield loss due to the second generation larvae of B. fusca in Awassa.

Effect of age of worker honey bees ( Apis mellifera ) on tracheal mite ( Acarapis woodi ) infestation

Abstract: The susceptibility of worker honey bees,Apis mellifera L., as a function of age, to infestation by tracheal mites,Acarapis woodi Rennie, was investigated. Bees 4 days old were rarely infested in colonies during active brood rearing. Only 2 of 255 bees >8 days old, and 1 of 246 bees >16 days old, became infested. Most of the eggs found in bees>3 weeks old apparently were produced by the progeny of the original infestation.

Infestation Rates of Papaya by Fruit Flies (Diptera: Tephritidae) in Relation to the Degree of Fruit Ripeness

Abstract: Infestation rates of oriental fruit fly, Dacus dorsalis Hendel, and melon fly, Dacus cucurbitae Coquillett, were determined in mature green, color-break, quarter, half, three-fourth, and fully ripe papaya ( Carica papaya L. cv. Kapoho Solo) fruits. These qualitative ripeness descriptions were based on the extent of the fruits’ yellow color development. Infestation rates of papaya by the two species of Dacus increased with the increase in degree of fruit ripeness. The density of oriental fruit flies in papaya was much greater than that of melon flies, especially in half- to fully ripe fruits. The 1949-1981 survey record data and the 1979-1986 field infestation data revealed a gradual increase in the occurrence of melon flies in papaya, apparently because of changes in the farmers’ cultural practice. Papaya, which has been considered as an “occasional host” of the melon fly, is becoming a more common host under unsanitary field cultural conditions. Results of our study are discussed in relation to the biology and ecology of the two species of Dacus and in the development of regulatory quarantine treatments designed to disinfest papaya with the fruit flies.

Phytophthora spp. in indigenous forests in australia

Abstract: Indigenous forests in Australia are managed primarily for timber production, water production, and conservation. Soil infestation by Phytophthora spp. has the potential to affect all of these. Infestation is widespread but is perceived to affect timber production only in the mixed species eucalypt forests in Victoria and the Eucalyptus marginata Donn ex Sm. (jarrah) forest in Western Australia. It is known to affect water production in Western Australia. As Phytophthora spp. have a very wide host range, site infestation leads to vegetation changes which reduce the conservation value of indigenous forests and similar plant communities in southern Australia.

Reduction of European Corn Borer (Lepidoptera: Pyralidae) Damage by Intercropping Corn with Soybean

Abstract: Corn, Zea mays L., and soybean, Glycine max (L.) Merrill, were intercropped for silage in 1985 and 1986 at the Central Experimental Farm, Ottawa, to determine effects on yields and the percentage of European corn borer, Ostrinia nubilalis Hubner, infestation. A 2 × 2 × 3 factorial was analyzed with two corn hybrids (dwarf PAG 391134 and tall Coop 5259), two corn cropping systems (monocropped and intercropped), and three nitrogen fertilizer levels (0, 60, and 120 kg N/ha). Intercropping significantly reduced European corn borer infestation in tall corn in 1985 and in both corn hybrids in 1986. Dwarf corn was infested significantly less than tall corn in both years and in both cropping systems. The commonly applied rate of 120 kg N/ha resulted in the highest European corn borer infestation. Yields and land equivalent ratios at 60 kg N/ha were as high as those at 120 kg N/ha, but European corn borer infestation was significantly less at 60 kg N/ha. Application of 0 kg N/ha resulted in the lowest yields and land equivalent ratios, but European corn borer infestation was not different from levels at 60 kg N/ha.

Variations in Damage to Wheat Caused by Russian Wheat Aphid (Homoptera: Aphididae) in Texas

Abstract: The Russian wheat aphid, Diuraphis noxia (Mordvilko), was discovered in Texas on wheat, Triticum aestivum L., in 1986, and 17 collections from 11 Texas counties were made that same year. Two Russian wheat aphid collections, designated as the Randall 2290 colony and the Swisher colony, were tested on four wheat varieties with three infestation levels to differentiate susceptible and resistant plants. Two aphids per plant were the best initial infestation level because higher levels caused too much damage and masked differences between the wheat varieties. Plant height, expressed as a percentage of an uninfested check, was a nonsubjective measure of plant response to Russian wheat aphid. In a second test, all 17 collections were tested on TX78V2290-36-1(TXGH2290) and ‘TAM 107’ with an initial infestation level of two aphids per plant. The results from the second test indicated that there were significant variations in damage between aphid cultures, and differences between colonies occurred within counties and between counties. Reproductive capacity of Russian wheat aphid was affected by variety and was highest overall on TXGH2290. We suggest that TXGH2290 could be used as a susceptible standard in future host plant resistant studies, and this breeding line has been recommended for release. These findings indicate that there are important genetic differences within Russian wheat aphid.

Seasonal and regional infestation characteristics of three ectoparasites of whiting, Merlangim merlangus L., in the North Sea

Abstract: Whiting collected from 36 stations in the North Sea in August 1985 and February 1986 were examined with reference to the prevalence, intensity and microhabitat utilization of three ectoparasites, namely Lernaeocera branchialis (Copepoda: Pennellidae), Clavella adunca (Copepoda: Lernaeopodidae) and Diclidophora merlangi (Monogenea: Polyopisthocotylea). Maximum prevalences and mean intensities, at any one station, for the three parasites were 74,45.48,60% and 1.07,0.56 and 1.30, respectively. At the stations sampled, infestation levels with L. branchialis and C. adunca were significantly higher in the winter than in the summer, with winter mean parasitic intensities being between five and eight times higher than those in summer. A converse situation applied with D. merlangi, with summer mean intensities being over four times larger than those in winter. Pooled winter and summer parasitic infestation data, from the 36 stations, enabled large-scale zoogeographical parasitization patterns to be recognized. Both L. branchialis and C. adunca are rarely seen on whiting in the North Sea north of latitude 56° N. South of this latitude, prevalences and intensities of L. branchialis are higher on the eastern than on the western side of the sampling zone, while those of C. adunca are similar on both sides of the North Sea. D. merlangi's infestation exhibits a striking latitudinal cline in the study area, with prevalences and intensities increasing steadily from south to north. All three ectoparasites were non-randomly distributed within the whiting gill and/or buccal cavities and showed marked microhabitat preferences. Possible explanations for the seasonal and geographical variations in the parasitic infestations are discussed.

Effect of population density of immatures on survival and development of the western corn rootworm (coleoptera: chrysomelidae)

Abstract: A field study with controlled infestations of eggs of the western corn rootworm, Diabrotica virgifera virgifera LeConte, was conducted over a four-year period. The percentage of insects surviving to adulthood was significantly reduced at an infestation of 2400 eggs per 0.3 m of row compared with rates of 300, 600, and 1200 eggs per 0.3 m of row. Survival to adulthood varied among years suggesting that biotic or abiotic factors in the soil, possibly soil moisture, may have influenced survival. The Julian date associated with mean adult emergence was significantly later at the 2400 egg infestation rate than at lower rates. These results suggest that immature survival is reduced and developmental time increased at high population densities.

The prevalence of head louse infestation among urban and rural children in Korea

Abstract: The prevalence of head louse (Pediculus hamanus var capitis) infestation in preschool and school children in 9 urban and 8 rural areas of Korea, was investigated Of 11,865 children who were examined for head lice and nits, 2,900(244%) were found infested The over-all infestation rate of rural children, 589%, was higher than that of urban children, 144% There also existed significant differences in the infestation rate among various regions of urban as well as rural areas Females were more infested than males But there was no differences in infestation rate in either sex of preschool age The infestation rate increased gradually from the age of 6, reached a plateau between 9-12 years of age and thereafter slowly decreased The infestation rate of an orphanage children was higher than that of general childhood population Health education and mass-delousing attempt are urgently required to lower such a high prevalence of head louse infestation in Korea

Tracheal Mite (Acari: Tarsonemidae) Infestation Effects on Foraging and Survivorship of Honey Bees (Hymenoptera: Apidae)

Abstract: The foraging activity of worker honey bees, Apis mellifera L., at the hive entrance was used to study the effects of infestation by tracheal mites, Acarapis woodi (Rennie). No significant differences were found between infested and noninfested bees for the number of foraging trips, frequency of foraging trips, round trip times, frequency of pollen collection, or time between foraging trips. Nectar loads collected by forager honey bees infested with tracheal mites were compared with loads collected by noninfested foragers. The difference in mean honey sac volumes was not significant. Survivorship of worker bees as a function of tracheal mite infestation was determined by comparing, during a 6-wk period, the ratio of infested to noninfested bees in subpopulations that were aged in common colonies. Stable infestation ratios throughout the experiment indicated no significant reduction in survivorship because of infestation.

Assessment of Yield Loss of Sorghum and Pearl Millet due to Stem Borer Damage

Abstract: The stem borer species that infest sorghum and pearl millet are listed. At ICRISAT Center in India, loss in grain yield due to Chilo partellus damage in sorghum was estimated by two methods. These experiments involving the phased use of carbofuran, or artificial infestation using laboratory-reared first instar larvae showed that maximum grain yield loss occurred when infestation took place 15-30 days after crop emergence. The maximum number of deadhearts was formed when infestation took place during this period. Stem tunneling caused by later infestations did not cause a reduction in grain yield. In two studies at the ICRISAT Sahelian Center in Niger, results showed that under low levels of borer infestation (caused by Coniesta ignefusalis), a nonprotected pearl millet crop gave slightly higher yields than one that was protected by insecticide. In a date of sowing trial, losses were heavier on late-sown millet with an increase in proportion of nonproductive tillers. Yield loss caused by other borer species are also discussed.

Disease and mortality in small ruminants in the North West Province of Cameroon.

Abstract: Mortality rates and the prevalence of disease were assessed in 115 flocks of traditionally managed sheep and goats in two Divisions of the North West Province of Cameroon by means of a questionnaire to the owners. The mortality rate was significantly higher in sheep than in goats and also higher in young stock than in adults. Tethering the animals during the day resulted in significantly lower mortality in both adult and young sheep and also in kids. Disease problems of small ruminants, identified on the basis of signs reported by their owners, included intestinal parasitism, especially helminthosis, tick infestation and associated diseases, pneumonia, goat plague(peste des petits ruminants) andOestrus ovis infestation. Treatment of sick animals was only practised on a very small scale, often by possible ineffective traditional methods. The owners identified tick infestation and diarrhoea as common causes of death. Recommendations are made on control measures suitable for application in this area.

Observations on successive infestations of the rabbit host by the ticks Rhipicephalus appendiculatus and R. zambeziensis (Acari: Ixodidae).

Abstract: Successive infestation of the rabbit host by instars of the brown ear tickRhipicephalus appendiculatus resulted in a progressive decline in engorgement and egg weights of adult instars and a reduction in percentage recovery of nymphs and larvae. Repetitive infestation with adults and larvae resulted in increased skin hypersensitivity reactions at the attachment site. Successive infestation withR. zambeziensis caused a more significant decline in engorgement and egg weights of adults than forR. appendiculatus. Percentage recoveries of larvae and nymphs were also significantly reduced. A cross-infestation study indicated thatR. appendiculatus andR. zambeziensis share antigenic moieties.

Insect pests of pearl millet in Sahelian West Africa I. Acigona ignefusalis (Pyralidae, Lepidoptera): Distribution, population dynamics and assessment of crop damage†

Abstract: Pests were surveyed in farmers’ fields in Burkina Faso, Niger and northern Nigeria from 1980 to 1983, and field trials at research stations in Burkina Faso (1980 and 1981) and at the ICRISAT Sahelian Center in Niger (1984 and 1985). Acigona ignefusalis is widely distributed in West Africa but its predominance as the major stem borer of millet varies with location. There are two generations of the pest annually, with peaks in moth population in July and September. Diapausing larval population declines during the dry season from November to May. A progressive decline in borer infestation was recorded between 1983 and 1985 in Niger. Damage to early‐sown millet was usually low while late sowing resulted in severe stem tunnelling and unproductive tillers. However, under low levels of borer infestation an unprotected crop gave higher grain yield than one which was protected with insecticide.

Quality losses in wheat caused by the orange wheat blossom midge Sitodiplosis mosellana

Abstract: Summary In three sets of data pooled over spring wheat varieties and lines a number of grain quality measurements were related to the levels of infestation by Sitodiplosis mosellana larvae. The Hagberg falling number value was negatively correlated with the proportion of damaged grains. The 1000-grain weight, protein content and gluten content were not affected. Differences between cultivars in infestation and damage level were found to depend on the development phenology (timing of ear emergence) and on the percentage of damaged grains remaining in the yield after harvest. The falling number values were reduced most when the attainable values remained low in cultivars prone to sprouting damage, and in seasons with unfavourable weather conditions for quality maintenance. The proportion of damaged grains in relation to the number of larvae was well described by a logit-transformed regression. Sampling for infestation level and preventive measures against quality loss are discussed.

Observations on a trial of broadcast burning to control an infestation of the mountain pine beetle Dendroctonus ponderosae

Abstract: The mountain pine beetle, Dendroctonus ponderosae Hopk., causes extensive mortality of lodgepole pine, Pinus contorta var. latifolia Engelm., throughout western North America (Van Sickle 1982). The Prince Rupert Forest Region, in the northwest of British Columbia, initiated an aggressive beetle management program in 1981. Logging of infested stands, and winter felling and burning of individual infested trees are the most common direct control techniques.The “Bristol Lake” infestation developed in the Bulkley Forest District, approximately 55 km northwest of Smithers, B.C., on a steep rocky ridge within the valley of Harold Price Creek. The area contained large volumes of mature lodgepole pine, and control of the infestation was therefore considered critical to the local beetle management plan, but the size (50 ha) and rough topography of the infested area precluded normal direct control measures.

Prevalence of body lice in elementary school students in three Ethiopian towns at different altitudes.

Abstract: A survey of body lice in three different altitudinal zones of Ethiopia was conducted. The survey population consisted of primary school children of both sexes ranging in age from 6-25 years. The areas of study were Gambela, Kemise and Debre-Berhan. Only 33.2% of the school children were found to be free from infestation and the rest, 66.8%, harboured body lice ranging in number of 1 to 598. The prevalence in Debre-Berhan (76.2%) was found to be significantly higher (p less than 0.001) than in Gambela (61.4%) and Kemise (62.6%). Similarly the density of lice was higher (P less than 0.001) among Debre-Berhan than among Gambela or Kemise school children. Infestation was commoner among the 11-15 and 16-20 year than the 6-10 and 21-25 year ago groups. There was no difference in the prevalence of lice between the sexes but a higher density was observed among males. The importance of having prior knowledge of the prevalence and abundance of body lice in different areas has been discussed in relation to possible outbreaks of louse-borne diseases.

Effect of Willamette Mite (Acari: Tetranychidae) on Grape Productivity and Quality: A Reappraisal

Abstract: Feeding damage by Willamette mite, Eotetranychus willamettei Ewing, reduced soluble solids per grape berry during the first year of infestation. After infestation for two years, total fruit weight per vine was reduced by 17.9% at 1,308 mite-days (one mite feeding for 1 d). Mean berry size was reduced by 8% at 1,308 mite-days. No statistically significant reductions in pruning weight, shoot growth, or trunk girth were observed. No changes in soluble solids per berry were detected during the second year of the study. Hypotheses are discussed to explain apparent contradictions with previous studies and implications for threshold recommendations.

Use of Decis® and Systoate® for the Control of Maruca Testulalis (Geyer) in Cowpea

Abstract: A schedule of insecticide spray combining two insecticides: Decis®(deltamethrin) and Systoate® (dimethoate) with four times of spray: 35, 45, 55 and 65 days after planting (DAP) was investigated in order to search for the most effective treatment against Maruca testulalis (Geyer) population on cowpea (Vigna unguiculata (L.) Walp). The local cowpea cultivar “Kpodjiguegue" was used to study the onset and fluctuation of M. testulalis larvae infestation on cowpea terminal shoots, flowers and pods. The trial was carried out during the 1985 early cropping season at Abomey-Cala vi. The treatments’ effect on M. testulalis in the terminal shoots was not significant at the 5 % level of probability because of the very low infestation of this part of the plant. In the flowers and pods, Decis® was better than Systoate® which failed in controlling this borer satisfactorily. In the unsprayed plots (i.e. control), the peak of the natural infestation occurred in the flowers towards 50 DAP and 65% of the flowers were injured. In the pods, up to 89% of infestation by M. testulalis larvae were observed 60 DAP. The lowest yield was recorded from the unprotected plots (322 kg/ha) whereas the treatment 0-Decis®Systoate®Decis® provided the highest yield (1367 kg/ ha) and the highest returns.