Highest Number Of Larvae Research Articles

Continuous-flow apheresis of microfilariae in Loa loa infestations

Loiasis is endemic in the tropical rain forest of Central and some parts of West Africa and is transmitted by the insect vector Chrysops silacea and Chrysops dimidiata. Loa loa infestation causes local inflammation due to migrating adult worms in the subcutis (Calabar swelling) and in the conjunctivae (eye worm). The diagnosis is made by the demonstration of circulating blood microfilariae, the larvae of the adult worms. Since the density of the microfilariae is very low, they can only be identified by concentration methods, such as hemofiltration. During treatment with the specific antiparasitic drug (diethylcarbamazine, DEC), side effects such as allergic reactions due to the rapid disruption of circulating microfilariae may occur. Those symptoms are aggravated in patients with a high number of larvae, leading to meningo-encephalomyelitis or even death. 1 Since microfilariae accumulate in the buffy coat during leukocytapheresis, 2 it was thought that this technique might be a suitable tool to reduce the parasite load and to bypass the side effects of specific drug treatment. Muylle et al. achieved apheresis of microfilariae in two patients with Loa loa infestation by using a Haemonetics, M-300 blood processor. 3 The authors studied two patients with an excessive microfilarial count in the peripheral blood of up to 9/μL and achieved a high enrichment by discontinuous-flow centrifugation. A similar observation was reported by Saeed et al. later on. 4 We have studied two patients with loiasis and report the results of microfilarial apheresis using a continuous-flow IBM/Cobe cell separator.

Frequency of Dacus oleae (Gmelin) immature stages and their parasites in seven olive varieties in Jordan

The study showed three generations of the olive fruit fly from June to November 1984. Eggs were first detected in the Shami variety in early June. There were three peaks of eggs found in almost all varieties in late June, late August and late October. Highest number of larvae was found in Santa in July, and Ascolano and Kheli in August. There were no significant differences in the number of larvae per 100 infested fruits between all varieties during the first generation except Nabali. Pupae inside the fruits first appeared in Shami in July. The number of pupae inside the fruits was high in all varieties in August. Holes made by larvae falling to the soil for pupation were recorded in early August in all varieties, except Nabali where they appeared in late August and early September. During the second generation the highest number of larvae was found in Ascolano, Santa and Rase’e varieties. The recorded parasites were Opius concolor, Eupolmus urozonus, Tetrastichus sp., Trichostereresis glabra, and Lasioglassum sp. The most abundant parasites were O. concolor and Tetrastichus sp.

Importance of physical properties of artificial diet for the pink stem borer, Sesamia inferens Walker

Moisture content, hardness or consistency, and age of diet were some of the properties studied for their effect on survival, growth and development of Sesamia inferens Walker. Survival of larvae was maximum on diet with 66.1% moisture. Increase or decrease in moisture resulted in excessive stickiness or dryness to the diet. Reduction in moisture content in the artificial diet was dependent on particle size of bulk constituent. Proper consistency or hardness resulting from 1.8 and 2.2% agar permitted higher number of larvae to reach pupal stage. Diet stored for 24 hr and 48 hr provided favourable conditions for the early instar larvae to establish on the diet.

Predicting Apple Injury Caused by Platynota idaeusalis (Lepidoptera: Tortricidae) from Summer Brood Sampling

Linear and multiple regression analysis was used to evaluate four methods that sampled summer brood tufted apple bud moth (TABM), Platynota idaeusalis (Walker), egg masses, larvae, or fruit injury, to predict apple injury caused by fall brood larvae. Summer brood egg masses were low in number and generally were not a significant factor in the regression models. Only high percentages of summer brood fruit injury or high numbers of larvae were significant. Summer brood larvae was consistently the best predictor of fall brood fruit injury. The best sampling method to predict fall brood fruit injury was 5-min timed counts taken during late July–early August. These counts explained comparatively larger percentages of variation (generally r2 values >0.60) with comparatively less sampling effort.

Variation in the costs and benefits of mutualism: the interaction between yuccas and yucca moths.

Yucca moths are both obligate pollinators and obligate seed predators of yuccas. I measured the costs and net benefits per fruit arising for eight species of yuccas from their interaction with the yucca moth Tegeticula yuccasella. Yucca moths decrease the production of viable seeds as a result of oviposition by adults and feeding by larvae. Oviposition through the ovary wall caused 2.3-28.6% of ovules per locule to fail to develop, leaving fruit with constrictions, and overall, 0.6-6.6% of ovules per fruit were lost to oviposition by yucca moths. Individual yucca moth larvae ate 18.0-43.6% of the ovules in a locule. However, because of the number of larvae per fruit and the proportion of viable seeds, yucca moth larvae consumed only 0.0-13.6% of potentially viable ovules per fruit. Given both oviposition and feeding effects, yucca moths decreased viable seed production by 0.6-19.5%. The ratio of costs to (gross) benefits varied from 0% to 30%, indicating that up to 30% of the benefits available to yuccas are subsequently lost to yucca moths. The costs are both lower and more variable than in a similar pollinator-seed predator mutualism involving figs and fig wasps.There were differences between species of yuccas in the costs of associating with yucca moths. Yuccas with baccate fruit experienced lower costs than species with capsular fruit. There were also differences in costs between populations within species and high variation in costs between fruit within populations. High variability was the result of no yucca moth larvae being present in over 50% of the fruit in some populations, while other fruit produced up to 24 larvae. I present hypotheses explaining both the absence and high numbers of larvae per fruit.

Krill larvae in the Atlantic sector of the Southern Ocean during FIBEX 1981

During the First International BIOMASS Experiment krill larvae were sampled by several research vessels. The present paper compiles data gathered by of Polish, German and Argentinian expeditions undertaken during 19 January–19 March 1981 in the Scotia Sea, Drake Passage and Bransfield Strait regions. In the 1980/81 season the most intense spawing occurred at the end of December and in the beginning of January. In the eastern part of the region development of krill larvae was much more advanced than further to the west. The highest numbers of larvae were observed in the central part of the survey area, in the open ocean and on the shelf slope zones. In the Bransfield Strait larvae were most abundant in the north and north-east. These larvae appeard to have drifted to the north and north-east and occurred outside the region of the main concentrations of adult krill. As such, larval distribution reflected a meandering current at a reference level of 500 db, which was flowing in a general south-west to north-easterly direction. The Weddell Scotia Confluence did not form a border either to the occurrence of krill larvae or of adults.

Long-term trends in the distribution, abundance and seasonal occurrence of larvae of mackerel (Scomber scombrus L.) around the British Isles, 1948–1978

The distribution, abundance and seasonal occurrence of larvae of mackerel (Scomber scombrus L.) are described from routine Continuous Plankton Recorder (CPR) sampling around the British Isles over the period 1948–78, and from more intensive CPR sampling in the Celtic Sea in 1977. There were two main areas of larval concentration: in the North Sea and over and adjacent to the Celtic Plateau; subsidiary aggregations were observed to the northwest of Ireland and to the west of Norway. There were some similarities between the distribution of larvae around the British Isles and that of adult Calanus spp. In the North Sea there was a southerly shift of larval distribution over the period 1948–77; over a similar period the abundance of larvae increased to reach high numbers by the late 1950s and subsequently declined after the mid-6os. To the south-west of the British Isles numbers of larvae showed a long-term decline. The long-term trends of distribution and abundance are discussed in relation to concurrent biological and environmental change. The clearest relationship was found between the numbers of mackerel larvae in the North Sea and sea-surface temperature in the North Atlantic, which suggests a common causative agent for both sets of observations; also, there was a weak relationship with both spawning stock biomass and sea-surface temperature at the spawning areas. In the North Sea the seasonal occurrence of larvae was from May to August, the majority being taken in June and July; over the period 1948–77 the seasonal time of occurrence of highest numbers of larvae has remained relatively constant. In the Celtic Sea the seasonal occurrence of larvae was spread over a longer period, from March to August, with relatively high numbers from March to June; over the period 1950–78 the time of occurrence has been variable, possibly with a tendency towards later timing in more recent years.

Timing Insecticide Control of Rhododendron Borer 1 with Pheromone Trap Catches of Males 3

Spray treatments for control of Synanthedon rhododendri (Beutenmuller) were successful when they were timed to coincide with male flight activity by using a pheromone trap baited with isomers of 3,13-octadecadien-1-ol acetate. Male flight in Maryland begins in the last week in May and ceases within the first week of July. When chlorpyrifos was applied to rhododendron plants on 15 June and again on 6 July, the borer was completely controlled, and good control was obtained with only one application. Lindane gave partial control; acephate was relatively ineffective. The highest number of larvae recovered was 55 from an untreated plant.

The sheep headfly, Hydrotaea irritans (Fallén) (Diptera: Muscidae): biology of immature stages in the soil

AbstractSampling in Northumberland, England, and southern Scotland of pasture soils, the major larval habitat of Hydrotaea irritans (Fall.), showed larvel densities of between 0 and 30/m2; 15 different sites were examined, and all produced larvae. Larvae were found from September until June, larvael development continuing in the soil for about eight months. A study of the distribution within a single field that larvae were not confined to the wooded margins but occurred in significant numbers throughout the field. Higher numbers of larvae were present in the soil beneath cow pats than in the open field, but the proportion relative to the total population is small. Larvae prey was predominantly dipterous and coleopterous larvae. Pupation took place in the top 5 cm of pasture soil during May and lasted until late June. Emergence of adults took place from June until late July; males and females emerged over the same period

Diel Periodicity of Chironomid 1 Larval and Pupal Drift in an Urban Flood Control Channel System

The diel drift periodicity of chironomid larvae and pupae in a flood control channel system was investigated on 4 occasions. A 15-min drift sample was collected every h over a period of 24 h by using a 130-μm pore plankton net. Hourly changes in current velocity and water temperature, and time of sunset and sunrise were recorded during each diel period. Larvae and pupae of Cricotopus bicinctus (Meigen), C. sylvestris (F.), Chironomus decorus Johannsen, and pupae of Paralauterborniella subcincta (Townes) drifted in higher numbers in darkness than in the daylight periods, with maximum numbers occurring within 5 h after sunset. Larvae of P. subcincta drifted more during the daytime. Water temperature and current velocity seem to have very little effect on numerical increases or decreases of these midge species in drift, except for larvae of P. subcincta . Darkness is considered to be the major entraining factor for the higher numbers of larvae and pupae of C. bicinctus , C. sylvestris , C. decorus , and pupae of P. subcincta occuring in drift during a diet period.

Lungworms in the Rocky Mountain bighorn sheep of western Canada.

In 58 sets of lungs from bighorns from western Alberta or eastern British Columbia, 91% were infected with Protostrongylus stilesi, and 38% were infected with P. rushi. Four of the five sheep free of P. stilesi were lambs. Lungs from nine near-term fetuses were negative for lungworms.All but 1 of 409 field-collected fecal samples from the same ranges contained larvae of Protostrongylus spp.; counts of larvae per gram of dry feces suggest a clumped distribution of lungworms. Analysis of monthly samples from one herd indicated a significant seasonal variation, with high numbers of larvae shed by bighorns on winter range. The use of fecal analyses in assessing severity of infection and the evolutionary significance of the clumped distribution of lungworms are discussed.

Mass Rearing Pink Bollworms1

The use of physical barriers between ¼-in. cubes of a semisynthetic diet allowed mass rearing of pink bollworms, Pectinophora gossypiella (Saunders). A layer of nonabsorbent cotton was the most effective barrier. A negative, highly significant correlation between number of larvae and percent moisture of medium was obtained for diets with 76 and 84% moisture. Medium containing 75% moisture produced the highest number of larvae. The most effective use of media and 1st instar larvae was obtained with 100 medium cubes and 100 larvae per 8-oz jar. Pink bollworms are now mass reared in 9-oz waxed-paper cups with ¼ in. cubes of medium scattered between layers of cotton.