Number Of Cocoons Research Articles

The use of mark-recapture to measure worker number in the rock nesting ant species, Formica neorufibarbis Emery

I examined the use of a mark-recapture technique to measure colony size and colony growth in the ant species Formica neorufibarbis. I addressed three questions: 1) Is the method reasonably accurate?, 2) is the method precise?, and 3) how many workers does the method kill? I found that estimates of colony sizes based on mark-recapture were similar to those estimated by colony excavation. The error in estimates of worker and cocoon number due to the binomial nature of the mark-recapture method was relatively small, with a mean coefficient of variation of twelve percent for workers and nine percent for cocoons. I estimated that the method killed less than two percent of the workers in a nest.

Host Age ofPseudaletia unipuncta(Lepidoptera: Noctuidae) and Parasitic Capacity ofGlyptapanteles militaris(Hymenoptera: Braconidae)

Successful use of Glyptapanteles militaris (Walsh) to control the polyphagous pest Pseudaletia unipuncta (Haworth) depends on knowledge of the host–parasite relationship. In this study, we determined the suitability of different P. unipuncta instars for oviposition by G. militaris females, and we evaluated the parasitoid performance on each host instar (L1 to L6). The following parameters were measured: percentage of larvae parasitized from which parasitoids emerged; percentage of host mortality; percentage of hosts that pupated after being stung by the parasitoid; egg–larval developmental time; pupal period; total developmental time; mean number of cocoons per host; mean number of parasitoid larvae that emerged from a host larva but failed to spin a cocoon; number of parasitoid larvae that failed to emerge from each host; total number of parasitoid larvae per host; parasitoid sex ratio and emergence rate of adult progeny. All host instars were stung by female parasitoids, but cocoons were never obtained from L6. The proportion of parasitized larvae increased from L1 to L4 then declined steeply, reaching no parasitism for L6, with a significant difference between L1 and L3, L4. Conversely, the proportion of host larvae that pupated decreased from L1 to L3, increased for L4 and L5, and slightly declined for L6. Significant differences were observed between L5, L6 and the other 4 instars. Similar results were observed for the proportion of larva killed before emergence of the parasites, with a significant difference between L6 and L2, L3. Host instar at the time of parasitization significantly affected egg–larval and total developmental time, the total number of parasitoid larvae per host, and the emergence rate of adult progeny. These results indicate that the 2nd, 3rd, and 4th instars of P. unipuncta were more suitable for G. militaris parasitism, because these instars provide a high percentage of hosts that will be successfully parasitized and they also produce large numbers of parasitoids per host.

Seasonal variations in growth and reproduction of the earthworm Perionyx excavatus (Oligochaeta: Megascolecidae)

One-week-old juveniles of Perionyx excavatus were cultured in urine-free cow manure for 16 weeks in three different seasons to find out the influence of environmental factors on growth and reproduction. The biomass of worms increased gradually until the 16th week in all seasons. There was no significant (F=2.51) variation in biomass between the three seasons; however, the growth rate varied significantly (F=50.49, P<0.01). During the pre-clitellar period, the growth rate (mg/g) increased steeply (1013.17±41.33 in the monsoon season, 728.64±15.5 in winter and 463.16±22.96 in summer) until the worms attained maturity (5–8 weeks) and from then onwards gradually decreased after the commencement of cocoon production. Worms attained maturity when the mean weight of each worm ranged from 167.46 mg to 197.13 mg. The cumulative number of cocoons varied significantly (F=26.07, P<0.01) with season. Similarly, the rate of cocoon production also varied significantly (F=62.06, P<0.01). The average rate of cocoon production was 7.23, 0.99 and 0.53/worm/week in the monsoon season, winter and summer, respectively. By week 16, the ratio of weight gain to the initial weight of 1-week-old juveniles was 1 : 43.13 in the monsoon season, 1 : 30.49 in the winter and 1 : 23.69 in the summer. The maximum mass gain, growth rate, and cocoon production and earliest attainment of maturity were recorded during the monsoon season, and were attributed to the lowest range of fluctuating temperatures and high humidity compared with during winter and summer. The growth rate of worms in all seasons was inversely proportional to the number of cocoons produced. Further, the higher the rate of cocoon production, the lower the weight of individual cocoons.

Sediment Toxicity Bioassays for Assessment of Contaminated Sites in the Nervion River (Northern Spain). 2. Tubifex tubifex Reproduction Sediment Bioassay

Toxicity assessment based on sediment chronic bioassays with the aquatic worm Tubifex tubifex was performed at ten contaminated sites in the industrial area of Bilbao (Northern Spain). One control and three reference sites were also included. Tubifex bioassay measures both survival and reproduction impairment. These endpoints have been contrasted and discussed in relation to somatic growth and both individual and total biomass of cocoons. Survival was only affected at one site which was heavily contaminated by organic compounds, mainly PAHs. A group of four severely ecotoxic sediments was characterised by a drastic reduction in number and size of cocoons, and adult somatic growth. In other group of sediments, some significant increases were found for these variables. It is suggested that these increases represent an effect of hormesis. An index of reproductive effort was used to integrate the relationship between somatic growth and reproduction. Values of reproductive effort at the test sediments were lower than those at the control sediment, suggesting a conservative strategy of oligochaete worms which consisted in an investment into somatic line (growth) at the expenses of offspring. Rates of food consumption which were estimated from egestion rates, were low at the contaminated sites. This fact could be related to the low production levels found at these sites and may reflect avoidance feeding behaviour of the oligochaete worms within the sediments. At some reference sites, high production could have resulted from high nutritional quality of sediments, or to an hormetic effect due to low concentration of some chemicals. Results are discussed in relation to toxicity data from sediment three-brood bioassay with Daphnia magna Straus performed separately on the same sediments.

Reproduction of the earthworm Lumbricus terrestris Linné after the first mating

Mature virgin individuals of the simultaneously hermaphroditic earthworm Lumbricus terrestris Linné were housed in small groups and allowed access to each other under continuous video observation. After copulation, earthworms were isolated and thereafter their mass and the number of cocoons they produced were recorded monthly. Mated individuals produced cocoons for up to 12 months after the mating, while unmated individuals produced no cocoons. Hatchability of cocoons ranged from 76 to 62% over the 5 months following the mating, but decreased to 11% in the sixth month. Cocoons produced beyond that period failed to hatch. The median period of viable cocoon production was 3 months. Monthly cocoon production peaked 2-3 months after the mating, when 2-3 (1-2 viable) cocoons per individual were produced. Median total production of viable cocoons was 5 per individual (range 0-21). There was no discernible relationship between cocoon production and length of copulation, individual longevity, or individual mass at mating. Both partners usually contributed to the production of viable cocoons, but within mating pairs there was a median difference of 4 cocoons. Median survival time after the experimental mating period was 9 and 11 months for mated and unmated earthworms, respectively.

Perfectionnement des méthodes de production et de lâcher deCotesia melanoscela, parasite de début de saison deLymantria dispar

Rearing and release procedures forCotesia melanoscela (Ratzeburg) (Hymenoptera: Braconidae), an early-season parasitoid ofLymantria dispar (L.), were evaluated in 1995 and 1996 at the Beltsville Agricultural Research Center, Beltsville, Maryland, USA. Mass rearing procedures were developed during the winter/spring of 1995/1996 to produce diapausingC. melanoscela cocoons for experimentation. Program efficiency as measured by percent adult emergence was estimated to be 84% with a measured sex ratio of 48:52 M:F, at an estimated cost per 1 000 cocoons of U.S. $5.26 for materials and a labor requirement of approximately 6 hours. A host larvae:female parasitoid ratio of 100:1 was found to be most efficient in terms of number of parasitoid cocoons produced per female parasitoid, but a ratio of 100:2 was most efficient in terms of number of cocoons per rearing cup. OverwinteringC. melanoscela cocoons under natural conditions for 25 weeks (November placements) before expectedL. dispar egg hatch (mid-April) resulted in excellent synchrony with host egg hatch. Alternatively, holdingC. melanoscela cocoons in cold storage for 23 or more weeks at 5°C resulted in adult parasitoid emergence beginning 10 days after removal from cold storage, and proper timing of removal would result in similar synchrony of adult emergence with host egg hatch. These alternative release strategies give managers increased program flexibility.

Estimation of earthworm cocoon development time and its use in studies of in situ reproduction rates

Data from the literature on development rates of earthworm cocoons were used to predict the time of hatching of cocoons incubated in the field. The numerical integration of a deterministic equation with the incorporation of individual variation in development rate made it possible to predict the hatching time distribution of a sample of cocoons produced over one week with good precision. This was shown for three species of earthworms, Aporrectodea caliginosa, Allolobophora chlorotica, and Dendrobaena octaedra. By reversing the direction of time, the same algorithm finds the probability distribution for the expected production time of a cocoon, whose time of hatching is known. It is suggested that the method can be applied to cocoons sampled from soil cores and incubated in the laboratory. Thus, the most probable production time for each cocoon can be determined with its confidence interval; subsequently, the number of cocoons produced per square meter during a given time interval can be calculated. If the density of adult earthworms is known for the same time interval, the reproductive rate (based on surviving cocoons) can be estimated.

Spider Adaptation to Artificial Biotopes: The Fauna of Percolating Filter Beds in a Sewage Treatment Works

The spider faunas of two filter beds at the Minworth Sewage Treatment Works in Birmingham, UK, were studied from June 1980 to June 1981 inclusive, to investigate their role in this specialized community. The spider fauna was dominated by only two species, Leptorhoptrum robustum and Erigone longipalpis (Linyphiidae), although two others were able to live permanently in the stone medium, in very low numbers. The zonation of spiders throughout the 1.8 m depth was studied by using vertical shafts containing 10-12 canisters of stones which could be removed and sampled. The filter bed environment has a constant humidity, small variation in temperature, abundant food, and is relatively free from spider predators and parasites apart from entomophagous fungi. The lowest numbers of spiders were recorded in the winter and spring, and very high values were recorded in mid-summer when each individual spider had only 3.2 x 3.2 cm of stone surface and 2.5 cm 3 of air space. Immature specimens were always more numerous than adults except in winter and spring. The highest numbers of egg cocoons of both dominant species were recorded in October, but there was a long delay before the majority of the eggs hatched in May/June. The very high populations in June of over 67 000 m -3 coincided with massive aerial dispersal movements. The influence of toxic metals in the crude sewage on the spider fauna is discussed but no evidence was found that the populations were affected. An estimate is made of the potential ability of the spider fauna to control nuisance flies which breed in the filter beds. Control could be achieved by reducing the interruptions to sewage flow and confining shutdowns for maintenance work to early spring when populations are low. This would also reduce the incidence of spider bites among maintenance staff.

Anisopary in compost earthworm reproductive strategies (Oligochaeta)

Individual differences in the number of hatchlings and cocoons produced by Eisenia fetida have been recorded. We propose to call this phenomenon anisopary — unequal reproduction ( an — not, iso — the same, parere — to produce). The reproduction of individual partners from pairs of E. fetida were studied. The earthworms were mated for 72 h and then separated. In 85% of all matings one partner produced on average twice as many hatchlings as the other — in the remaining 15% the partners produced on average equal numbers of hatchlings. The biomass changes of the earthworm partners corresponded with the apparent reproductive functioning of the worms. We suggest that there are sperm donors — low producing (hypopary) and sperm receivers — high producing (hyperpary) earthworms.

The effects of feeding regime on the growth and reproduction of the medicinal leech Hirudo medicinalis

1. The feeding frequency, the size of meals, the number of meals required to attain reproductive maturity and the number of meals taken between iteroparous reproductive bouts were determined in the laboratory under optimal conditions for the medicinal leech Hirudo medicinalis fed exclusively on mammalian (bovine) blood. In addition the number of bouts of reproduction and the numbers of cocoons and hatchlings per cocoon produced were determined.2. The average time for H. medicinalis to reach reproductive maturity at 20°C was 289 days, at an average wet biomass of 8143 mg with two–nine separate bouts of cocoon production. The number of meals to first reproduction was 8.9 (mean meal size of 3066.7 mg), with a significant correlation between total mass of blood ingested and the numbers of reproductive bouts and number of cocoons produced. Mean lifetime cocoon production per individual was 12.43, with 3.9 hatchlings per cocoon.3. The significant positive relationships between ingestion, fecundity and developmental rate observed support the hypothesis that declining abundances of field populations of H. medicinalis are the result of lower available energy for growth, reflecting leeches now feeding predominantly on amphibian blood of lower energetic value than mammalian blood.

Effects of Metal-Contaminated Soils on the Growth, Sexual Development, and Early Cocoon Production of the EarthwormEisenia fetida,with Particular Reference to Zinc

JuvenileEisenia fetida(Savigny) were exposed for 20 weeks to an uncontaminated soil and to soils contaminated with cadmium, copper, lead, and zinc collected from seven sites at different distances from a smelting works at Avonmouth, southwest England. The survival, growth (= weight after 5 weeks exposure), time to sexual maturation (= percentages of adults present after 8 weeks), and reproduction (= number of cocoons produced by the worms) were compared with soil metal concentrations. Of the parameters measured, growth and sexual maturation time had the lowest EC50values. The effects of metal-contaminated soils could be attributed both to the direct toxicity of the metals and to changes in the “scope for growth” of the exposed worms. A comparison of the results with those of an earlier toxicity test conducted with adult worms indicated that juveniles are more sensitive to metals than adults. Significant toxic effects on the growth and sexual maturation times of juveniles were detected in soils from sites for which no significant effects on the cocoon production of adults could be detected. The greater sensitivity of juvenile worms indicates the importance of considering effects on a variety of life history stages when conducting a risk assessment of the effects of pollutants in soils. AlthoughE. fetidadoes not occur naturally in soils at Avonmouth, the present study provides evidence to support the suggestion that pollution from the smelter is responsible for the absence of worms within 2 km of the factory. Results presented in this paper, and from previous studies, suggest the observed absence is due to the effects of zinc on the growth and maturation of juveniles and the cocoon production rate of adult worms.

Tubificid Culture

Oligochaeta worm Tubifex sp., one of the best alive food for aquarium fish, has been cultured in the still water system. The worms were grown on three different substrates. The first substrate contained 50% fresh cow manure, 25% lake sand, and 25% garden soil. The second substrate contained 75% fresh cow manure and 25% lake sand. The third substrate contained 75% fresh cow manure and 25% garden soil. Growth and fecundity were observed in the three substrates. However, the highest growth nate, cocoon number and fecundity were found with the substratum containing 75% fresh cowmanure and 25% garden soil.

Differential effects of the acylurea insect growth regulator teflubenzuron on the adults of two endolarval parasitoids of Plutella xylostella, Cotesia plutellae and Diadegma semiclausum

AbstractThe acylurea chitin synthesis inhibitor, teflubenzuron (‘Nomolt’® SC) showed no apparent activity against adult males of Diadegma semiclausum Hellén or Cotesia plutellae Kurdj. when applied to foliage at a rate ( = 50 g a.i. ha−1) approximating to 2 × field usage. In contrast, the pyrethroid cypermethrin (‘Cymbush’® EC) showed appreciable foliar activity (at rates = 10–50 ga.i. ha−1) to D. semiclausum but showed low activity against C. plutellae. When single adult female D. semiclausum were pre‐treated with teflubenzuron (= 50 g a.i. ha−1) and then exposed to 5. 10. 25, 50 or 100 second‐instar host larvae, the number of purasitoid cocoons formed was significantly reduced compared with controls except at the lowest host density (P 0‐05). However, there was no evidence that teflubenzuron had a host density‐dependent effect on parasitism by D. semiclausum. Teflubenzuron had no significant effect on host parasitism in an equivalent experiment with C. plutellae (P &gt; 0‐05) except at the median host density. When batches of ten host larvae were introduced at hourly intervals to female D. semiclausum pre‐treated with teflubenzuron (= 50 g a.i. ha−1), the number of cocoons formed in the first two batches was not significantly different from untreated controls (P &gt; 0‐05), whereas teflubenzuron significantly reduced the number of cocoons in the next three batches of host larvae (P &lt; 0‐05). This suggests that teflubenzuron may affect chitin synthesis in developing eggs within female D. semiclausum but has little or no effect on pre‐formed eggs which are more likely to be oviposited first. Teflubenzuron had no significant (P &gt; 0‐05) effect on parasitism by C. plutellae when presented with batches of host larvae. When female D. semiclausum and C. plutellae were placed in the same host arena, the former showed a 3‐fold greater rate of parasitism. Pre‐treatment with teflubenzuron significantly reduced parasitism by D. semiclausum (P &gt; 0‐05) but had no significant effect with C. plutellae (P &gt; 0‐05) although the latter species failed to exploit the reduction in parasitism by D. semiclausum. The differential response of D. semiclausum and C. plutellae to insecticides is discussed in relation to the relative rates of establishment of these species in Malaysia.

Short-term effects of tillage and stubble management on earthworm populations in cropping systems in southern New South Wales

The effects of tillage and stubble management on the population distribution of earthworms were examined under wheat on a red-earth soil at Harden and under canola on a red-brown earth at Temora in the wheatbelt of southern New South Wales. At Harden, a five-year pasture had been followed by a conventionally cultivated oat crop in the year before the experiment. At Temora, a six-year pasture immediately preceded the experiment. Tillage treatments at Temora, and tillage and stubble treatments at Harden, were established during February-May 1990 and earthworm populations were measured in September. A number of earthworm species (Aporrectodea trapezoides, Microscolex dubius and M. phosphoreus) were present at both localities, but the introduced species A. trapezoides made up 97-99% of the earthworms collected. Earthworms were substantially more abundant at Temora (425 m-2) than at Harden (122 m-2). At Temora there was no effect of the intensity of tillage (4, 1 or 0 passes prior to sowing) on earthworm numbers. Earthworm densities were reduced in waterlogged soil. At Harden the direct-drill (DD) plots had a greater population density and biomass of earthworms and cocoons than the tilled plots. The size (mean weight) of adult earthworms, and the number of cocoons per adult, were also greater in the DD plots. However, no differences in earthworm populations were detected between minimum tillage (one cultivation prior to sowing) and stubble incorporation (three cultivations prior to sowing). On DD plots, burning stubble resulted in significantly smaller adult earthworms, a lower density of cocoons and a lower mean number of cocoons per adult than in the unburnt plots, but the differences in numerical abundance and in biomass were not statistically significant. Similarly, plots which had standing stubble contained fewer and smaller adults than those in which stubble was bashed and in close contact with the soil. There was a strong positive correlation between earthworm biomass and the amount of stubble present on the surface of the plots at the beginning of the winter (r2 = 0.64, P &lt; 0 01). The contrasting effects of tillage at the two sites and the impact of stubble management on earthworms are discussed in terms of the effects of recent paddock history and management practices on the amount, quality and distribution of suitable organic food for earthworms. The influence of these factors is reflected in the number, biomass and reproductive performance of the earthworms.

Cocoon number counting system by means of image processing

Cocoon number counting system by means of image processing

Control of the number of Cocoons Transferred in Three-steps toa Cocoon Supplier

Control of the number of Cocoons Transferred in Three-steps toa Cocoon Supplier

Studies on the Control of the Cocoon Number in the Cocoon Supplier of an Automatic Reeling Machine

Studies on the Control of the Cocoon Number in the Cocoon Supplier of an Automatic Reeling Machine

Spring Control of Pales Weevil on Fresh Cut Scotch Pine Stumps with Conventional and Experimental Formulations in Schyulkill Haven, Pennsylvania, 1992

Abstract Four treatments were applied to evaluate control of pales weevil on fresh cut stumps of Scotch pine Christmas trees. Each treatment was applied on 29 Apr and replicated four times in a randomized complete block design. Stump treatments were completed by drenching each stump with the formulation added to 360 ml of water. At treatment time, the following conditions existed: air temperature, 70°F; water pH, 7.0; 50% RH; and skies were sunny. At 167 DAT (13 Oct), the number of new chip cocoons was recorded to the first lateral root.

Cocoon number counting system by means of image processing.

Cocoon number counting system by means of image processing.

Side effects of selected pesticides on earthworms under laboratory and field conditions

Acute and sublethal toxic effects of the insecticides parathion and propoxur on earthworms were determined in laboratory and field tests. In acute toxicity tests according to OECD Guideline No. 207 Aporrectodea caliginosa SAV. and Aporrectodea longa UDE were more susceptible than Eisenia fetida SAV. In prolonged toxicity tests with E. fetida parathion significantly reduced the number of cocoons and surviving juveniles whereas propoxur reduced the number of surviving juveniles only. Results from these laboratory tests were used to explain species-specific effects of the insecticides in a field study.