Eggs and larvae

There are many species of parasitoids which do not appear to have viruses associated with their reproductive system (Vinson, unpublished) yet, these 

To meet these needs, parasitoids have evolved to respond to cues not only produced by the host, but also cues provided by the food and shelter of the host and associated organisms. While progress has been made in isolating and identifying the cues involved in host selection, most of the effort has centered on the short-range chemical cues of egg and larval parasitoids. Only a few studies have been conducted on the long-range cues. 

The co-evolution implied in the parasitoid-host relationship does not stop once a host has been attacked, but continues as the progeny develop within or on the host. The growih, development, physiology, and behavior of the host is 

I would like to express my appreciation to Ms Kathryn Edson, Mr Michael Strand, Richard Thomas and Gary Elzen for their suggestions and editorial help in the preparation of this manuscript. 

Vinson, S. B. and Ellis, J. S. (1981) Host discrimination by Chelonus insularis (Hym Braconidae), Telenomus heliothidis (Hym Scelionidae), and Tricho-gramma pretiosum (Hym Trichogrammatidae). Entomophagay 26, 149-56. 

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Worms - There are three types of worms found in water. For the most part, they dwell in the bed of the material at the bottom of lakes and streams. There they do important work as scavengers. The rotifiers are the only organisms in this category at or near the surfaee. They live primarily in stagnant fresh water. The eggs and larvae of various intestinal worms found in man and warm-blooded animals pollute the water at times. They do not generally cause widespread infection for several reasons. They are relatively few in number and are so large they can be filtered out of water with comparative ease. 

The Great Lakes have suffered the invasion of numerous exotic species of which the smelt, alewife and sea lamprey are probably the best known. More recently, two more species have entered the lakes probably via ballast water from foreign ships. The ruffe (Gymnocephalus cemuus) a small percid, feeds on the eggs and larvae of other percids and whitefish. The ruffe is currently considered to be a threat to Lake Superior s 5- 10 million whitefish fishery. The zebra mussel (Dreissena polymorpha) was discovered in Lake St. Clair in 1985 (31). It has subsequently been discovered at locations throughout the Great Lakes and is of major concern not only environmentally but economically. It has already colonized numerous industrial and domestic water intakes in sufficient numbers to entirely block water flow and is also an intermediate host to parasites which eventually invade fish. 

Finn, R.N. (2007). The physiology and toxicology of sahnonid eggs and larvae in relation to water quality criteria. Aquatic Toxicology 81, 337-354. 

Rudneva-Titova I. 1998. The biochemical effects of toxicants in developing eggs and larvae of Black Sea fish species. Mar Environ Res 46 499-500. 

Identification may be by gross examination for adult helminths or, more commonly, by microscopic examination for protozoa, helminth eggs, and larvae. The diagnostic forms of some parasites, such as the eggs of Ascaris spp., are present on a regular basis. Other forms, such as malaria parasites, Taenia eggs, or Giardia cysts, vary from day to day. 

In an ideal stain, the cytoplasm of cysts and trophozoites is blue-green tinged with purple. Entamoeba coli cyst cytoplasm is often more purple than that of other species. Nuclear chromatin, chromatoid bodies, erythrocytes, and bacteria stain red or purplish red. Other ingested particles such as yeasts often stain green. Parasite eggs and larvae usually stain red. Inflammatory cells and tissue cells stain in a fashion similar to that of protozoa. Color reactions may vary from the above. 

Meroplankton comprise organisms that spend only part of their life in the plankton. Primarily eggs and larvae of benthic or actively swimming adults fulfill this criterion, and the study of their chemical defense is often supported by the knowledge of defensive metabolites of their adult life stages. 

The defensive furanocembranes from the adult soft coral Sinularia poly-dactyla are also found in the eggs and larvae of their offspring. HPLC-com-parison of extracts from offspring with those from adults showed that pukalide (39) and 1 ip-acetoxypukalide (40) (Scheme 10) [87,88] are contained in both the blastula and planula of the soft coral [89]. Feeding assays with the larvae and their extracts showed that fish rejected the larvae due to chemical factors -most likely the pukalides. The pukalide-concentrations in the extracts of... 

Steenhard, N. R., Roepstorff, A., and Thamsborg, S. M. (2001). Inactivation of eggs and larvae of the cattle nematodes Ostertagia ostertagi and Cooperia oncophora after passage in pigs . Veterinary Parasitology, 101, 137-142. 

Klein-MacPhee, G., J.A. Cardin, and WJ. Berry. 1984. Effects of silver on eggs and larvae of the winter flounder. Trans. Amer. Fish. Soc. 113 247-251. 

Nominal LC50 values and standard deviation (SD) after 24 h of exposure to different LAS homologues and commercial LAS for seabream eggs and larvae, as well as ratio between LC50 (eggs) and LC50 (larvae)... 

Measured environmental concentrations of the different LAS homologues in the Sancti Petri Channel (San Fernando, Spain), nominal LC50 (24 h) values for eggs and larvae, as well as the ratio between environmental concentration and obtained LC50 (24 h) values... 

However, there are some potential effects of spilled oil on fish. The impacfs on fish are primarily to fhe eggs and larvae, wifh limited effecfs on fhe adulls. The sensitivity varies by species pink salmon fry are affected by exposure to water-soluble fractions of crnde oil, and pink salmon eggs are very tolerant to benzene and water-soluble petroleum. The general effects are difficnlt to assess and document quantitatively, dne to the seasonal and natural variability of the species. Fish rapidly metabolize aromatic hydrocarbons, due to their enzyme system. 

Farm animals ingest material from the ground, soil, or pasture that has been contaminated with feces containing eggs and larvae of helminths. Hence, they readily become infected and without a satisfactory treatment regimen, the cycle of expulsion and reinfection is perpetuated. Reinfection can occur within hours following treatment. 

Phytoplankton I Zooplankton Fish eggs and larvae Soft-bottom benthos Hard-bottom benthos Bottom fish Predatory fish Plant life Wetlands and estuaries Amphibians/reptiles Mammals Birds Water quality Human health... 

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