Egg Loss from the American Lobster, Homarus americanus, in Relation to Nemertean, Pseudocarcinonemertes homari, Infestation

1986 ◽  
Vol 43 (4) ◽  
pp. 772-780 ◽  
Author(s):  
Alan Campbell ◽  
John Brattey
Keyword(s):  
New Brunswick ◽  
Homarus Americanus ◽  
Egg Mass ◽  
American Lobster ◽  
Mass Destruction ◽  
Egg Incubation ◽  
Early Stages ◽  
Low Correlation ◽  
Incubation Periods ◽  
The Relationship

The relationship between nemertean (Pseudocarcinonemertes homari) infestaton and egg loss from ovigerous American lobsters, Homarus americanus, trapped near Grand Manan, New Brunswick, was investigated during 1980–83. The proportion of lobster eggs lost each month was variable, but generally increased to a maximum of 0.38–0.43 at the end of each of the three egg incubation periods. Up to 6.3% of the newly ovigerous lobsters tagged (N = 1413) during July–October 1982 has lost all their eggs by April–July 1983. Most ovigerous lobsters (74%) were infested with P. homari, but many lobsters had low mean densities of nemerteans (< 2/1000 lobster eggs). There was a significant but low correlation between P. homari densities and the proportion of eggs lost; however, egg losses could not be attributed solely to P. homari. Egg loss did not differ significantly between uninfested and nemertean-infested lobsters during each of the three egg incubation periods. The few lobsters that acquired high densities (> 4) of P. homari during the early stages of egg incubation appeared to suffer extensive or complete egg mass destruction. However, most lobsters maintained low densities (< 2) of nemerteans and hatched most (> 60%) of their eggs.

Aspects of the Biology of Pseudocarcinonemertes homari and Its Association with the American Lobster, Homarus americanus

1985 ◽  
Vol 42 (2) ◽  
pp. 351-356 ◽  
Author(s):  
D. E. Aiken ◽  
S. L. Waddy ◽  
L S. Uhazy
Keyword(s):  
Larval Development ◽  
Homarus Americanus ◽  
Egg Mass ◽  
American Lobster ◽  
Free Swimming ◽  
European Lobster ◽  
Newly Hatched Larvae

Pseudocarcinonemertes homari can reproduce on and destroy the egg mass of both the American (Homarus americanus) and the European lobster (H. gammarus) but does not appear to be a problem for brachyuran species. The eggs of P. homari are subspherical, average 251 × 260 μm, and are contained in individual compartments in a membranous brood sac that is attached to the lobster abdomen or egg mass. An average of 39 eggs occur in a brood sac. Newly hatched larvae are ciliated, lack anterior and posterior tufts, cirri or flagella, and are retained in the brood sac. Larval development is direct, and there is no free-swimming stage. After the larvae break out of the brood sac they join the adults and juveniles on the lobster egg mass. Many lobsters gradually remove infested eggs, but on those that do not, the nemertean population can increase to more than 14 000 individuals. After the lobster eggs are destroyed, the nemerteans disperse. Some form mucoid aggregations at protected sites on the exoskeleton; others move to the branchial chamber and gills or transfer to other lobsters. Reproduction occurs almost exclusively on the lobster egg mass, but P. homari appears capable of reproducing on lobster gills if denied access to lobster eggs for extended periods.

scholarly journals Biology of Brontocoris tabidus (Heteroptera: Pentatomidae) fed with Musca domestica (Diptera: Muscidae) larvae

2003 ◽  
Vol 63 (3) ◽  
pp. 463-468 ◽  
Author(s):  
P. Jusselino-Filho ◽  
J. C. Zanuncio ◽  
D. B. Fragoso ◽  
J. E Serrão ◽  
M. C. Lacerda
Keyword(s):  
Survival Rate ◽  
Musca Domestica ◽  
Reproductive Performance ◽  
Mass Rearing ◽  
Egg Mass ◽  
Egg Viability ◽  
Egg Incubation ◽  
Incubation Periods ◽  
Female Longevity ◽  
Heteroptera Pentatomidae

Development and reproductive performance of Brontocoris tabidus (Signoret) (Heteroptera: Pentatomidae) fed with Musca domestica L. (Diptera: Muscidae) larvae was evaluated. Duration of the nymphal phase of this predator was 31.2 days, with a 44.1% survival rate. Preoviposition and egg incubation periods and number of eggs/egg mass were 8.14 days, 5.6 days, and 45.4, respectively. B. tabidus presented 44.7% egg viability. Female longevity of this predator was 18.4 days. Results are discussed based on this prey use in mass rearing and maintenance of colonies of B. tabidus under laboratory conditions.

Relationship Between Destructive Grazing by the Sea Urchin, Strongylocentrotus droebachiensis, and the Abundance of American Lobster, Homarus americanus, on the Atlantic Coast of Nova Scotia

1981 ◽  
Vol 38 (11) ◽  
pp. 1339-1349 ◽  
Author(s):  
W. G. Wharton ◽  
K. H. Mann
Keyword(s):  
Population Structure ◽  
Nova Scotia ◽  
Sea Urchins ◽  
Atlantic Coast ◽  
Homarus Americanus ◽  
Strongylocentrotus Droebachiensis ◽  
American Lobster ◽  
History Of ◽  
Kelp Bed ◽  
The Relationship

Relationships between percentage cover of macroalgae, population structure of sea urchins (Strongylocentrotus droebachiensis), and the history of the lobster fishery were examined at nine sites distributed along the Atlantic coast of Nova Scotia from Guysborough County in the northeast to Pubnico in the southwest. At Pubnico there was dense algal cover and a small number of urchins living in crevices, and at Cape Sable there was an area of transition, but at all other sites there were urchin-dominated barren grounds. When the population structure of the urchins was compared with that previously observed in St. Margaret's Bay before, during, and after destruction of beds of kelp (Laminaria spp. and Agarum) by overgrazing, it was concluded that kelp bed destruction occurred on the coast north of Halifax prior to 1970, and on the coast south of Halifax after 1970. From the records of American lobster (Homarus americanus) catches it was concluded that a critical decline in catches at each site occurred a few years after kelp bed destruction. Information from various sources is synthesized into a coherent theory of the relationship between lobsters, other predators, sea urchins, and kelp.Key words: lobsters, Homarus americanus; sea urchins, Strongylocentrotus droebachiensis; destructive grazing, kelp, Laminaria, Agarum

Trapping interactions of crabs and American lobster in laboratory tanks

1995 ◽  
Vol 52 (2) ◽  
pp. 315-324 ◽  
Author(s):  
R. J. Miller ◽  
J. T. Addison
Keyword(s):  
Interspecific Interactions ◽  
Carcinus Maenas ◽  
Homarus Americanus ◽  
American Lobster ◽  
Target Species ◽  
Cancer Irroratus ◽  
Rock Crab ◽  
Trap Catches ◽  
The Relationship ◽  
Index Of Abundance

The relationship between trap catches of decapods and their abundance is not well established. Because it is difficult to manipulate density in the field, laboratory tanks were used to examine 10 hypotheses about the intra- and interspecific interactions of rock crab (Cancer irroratus), green crab (Carcinus maenas), and American lobster (Homarus americanus). The proportion of rock crabs captured did not differ among high, medium, and low densities, but the proportion captured was reduced at high densities for both green crabs and lobsters. Additional experiments demonstrated that large green and rock crabs in the tanks reduced the catch of small green and rock crabs and that the presence of lobsters reduced the catch of both crab species considerably. However, small rock crabs did not reduce the catch of large rock crabs, and neither green nor rock crabs reduced the catch of each other. Reductions in the catch of a target species caused by interactions in the field can perhaps be lessened by removing the catch from the trap at intervals of less than 24 h. Then the catches would be summed over 24 h for an index of abundance.

Temperature and Lobster, Homarus americanus, Yield Relationships

1991 ◽  
Vol 48 (11) ◽  
pp. 2073-2082 ◽  
Author(s):  
A. Campbell ◽  
D. J. Noakes ◽  
R. W. Elner
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
East Coast ◽  
Homarus Americanus ◽  
Fishing Effort ◽  
Sea Surface ◽  
Time Series Models ◽  
American Lobster ◽  
Sea Temperature ◽  
Survival And Growth

Commercial landings of American lobster (Homarus americanus) have increased dramatically in many areas along the east coast of Canada since the late 1970's. Average annual sea surface temperatures (SST) were analysed to test if lobster landings were related to changes in the marine environment. Time series models were fitted to lobster landings and SST data from Maine (USA), Halifax County (Nova Scotia), and Charlotte County (New Brunswick). Including temperature in the models improved forecasting ability for lobster catches for Maine and Halifax but not Charlotte. In Maine, lobster landings in year t were related to SST in year t. In Halifax, however, landings were related to SST in the previous 4 yr but not by SST of the current year. Lower fishing effort levels for Halifax compared with Maine probably extended the yield from strong year-classes through a number of years. We surmise that an increase in sea temperature near Halifax during the early 1980's increased the survival and growth rates of lobster juveniles. This provided a strong pulse of recruits to the fishery throughout coastal Nova Scotia during the mid- to late 1980's. Similar increases in temperature and landings were not observed for Maine and Charlotte.

Geographic Distribution and Seasonal Occurrence of the Nemertean Pseudocarcinonemertes homari on the American Lobster, Homarus americanus

1985 ◽  
Vol 42 (2) ◽  
pp. 360-367 ◽  
Author(s):  
J. Brattey ◽  
A. Campbell ◽  
A. E. Bagnall ◽  
L. S. Uhazy
Keyword(s):  
Homarus Americanus ◽  
Bay Of Fundy ◽  
American Lobster ◽  
Wild Populations ◽  
Intensity Of Infection ◽  
Egg Masses ◽  
Mean Intensity ◽  
Life History Stages ◽  
Egg Incubation ◽  
The Impact

Examination of 1041 trap-caught lobsters from the Bay of Fundy, Grand Manan, Browns and German Banks, south and east Nova Scotia, and Northumberland Strait indicated that Pseudocarcinonemertes homari occurs on American lobsters, Homarus americanus, throughout Canadian Maritime waters. Male lobsters were rarely infected and ovigerous females generally had a higher prevalence (percentage infected) and mean intensity of infection (number of nemerteans per infected lobster) than nonovigerous females. Sexually immature nemerteans were found on male and nonovigerous female lobsters, but all P. homari life history stages including brood sacs occurred on ovigerous lobsters. No seasonal trends were evident on ovigerous lobsters caught near Grand Manan; prevalence was consistently high (60–93%) and mean intensity ± SE was variable (15 ± 4.0 to 86 ± 63.1). The nemertean developed to maturity on ovigerous lobsters, reproduced on the host egg masses throughout the year, and appeared to produce three generations during a lobster egg incubation period. When lobsters completed egg incubation, nemertean reproduction ceased and some nemerteans either died, left the lobster, or perhaps were shed at molting. Prevalence and mean intensity increased with the size of ovigerous lobsters, and the distribution of nemerteans among ovigerous lobsters was highly aggregated. Ovigerous lobsters infected with >200 nemerteans had extensively damaged egg masses, but were rarely encountered (5 of 291). The impact of P. homari on the egg mortality of wild populations of H. americanus is unknown.

The biology ofDactylopius tomentosus(Hemiptera: Dactylopiidae)

2009 ◽  
Vol 99 (6) ◽  
pp. 551-559 ◽  
Author(s):  
C.W. Mathenge ◽  
P. Holford ◽  
J.H. Hoffmann ◽  
R. Spooner-Hart ◽  
G.A.C. Beattie ◽  
...  
Keyword(s):  
Incubation Period ◽  
Positive Relationship ◽  
Reproductive Potential ◽  
Egg Mass ◽  
Male Mating ◽  
Important Species ◽  
Egg Incubation ◽  
Strong Positive Relationship ◽  
Males And Females ◽  
The Relationship

AbstractDactylopius tomentosus(Lamarck) (Hemiptera: Dactylopiidae) is a cochineal insect whose host range is restricted toCylindropuntiaspecies (Caryophyllales: Cactaceae). This insect has been utilized successfully for biological control ofCylindropuntia imbricata(Haw.) F.M. Knuth in Australia and South Africa. Despite this, its biology has not been studied previously, probably due to the widely held belief that the biology of allDactylopiusspecies is similar. This study investigated the life cycle and the morphological and reproductive characteristics ofD. tomentosus. Results revealed some unique characteristics ofD. tomentosus: (i) eggs undergo a much longer incubation period, an average of 17 days compared to <1 day in its congeners; (ii) eggs are laid singly but are retained as an egg mass secured in a mesh of waxy threads attached to the female; (iii) the developmental times of males and females are longer compared to otherDactylopiusspp. due to a longer egg incubation period; (iv)D. tomentosusdoes not undergo parthenogenesis; (v)D. tomentosusis smaller in size than its congeners; and (vi) male mating capacity and reproductive potential were both high and variable between males. There was a significant, strong, positive relationship (r=0.93) between female mass and fecundity, whereas the relationship between the number of females mated per male that became gravid and their fecundity was negative (r=−0.68). Besides contributing to our knowledge of this economically important species, the finding of unique characteristics ofD. tomentosusbiology underlines the need to study each species in this genus.

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