Invertebrate food items

CL95 = 0.008-0.28 qgg ). Diazinon concentrations in earthworm samples were higher p < 0.005) in PA orchards, where rainfall was frequent, than in the more arid WA orchards. This difference also existed for live captured earthworms from PA and WA p < 0.017). A large number of samples are required to detect differences in pesticide exposures from living and dead invertebrates with confidence. Vertebrate exposures can be influenced by differential residue concentration for living and dead/moribund food items. 

The aquatic species chosen was Strongylocentrotus purpuratus, the purple sea urchin. This animal is a common resident of the California coast, a frequent pest in commercial kelp culture, and a specialty food item of growing interest. Phylogenetically, these echinoderms are considered to be in the invertebrate class most directly linked to the vertebrates. 

As with sessile animals and plants (see other chapters, this volume), the chemical deterrence of mobile invertebrates is best assessed using an approach in which ecologically relevant consumers are offered palatable food items with chemical extracts coated on, or embedded within, them.7 Assays in which the toxicity of compounds is assessed by dissolving them in the water containing the assay organisms have been repeatedly shown to bear no relation to the effects of compounds when ingested with prey.1 8,9 Most feeding deterrents of mobile invertebrates appear to be lipid-soluble, thus these... 

Hard-bodied terrestrial invertebrates (e.g., beetles, centipedes) can be exposed through incidental ingestion of pollutant-containing soil particles or through ingestion of food items (e.g., leaf litter or other soil organisms) that have taken up pollutants from soil. 

Small mammals (e.g., moles, mice, and voles) and certain bird species that live or nest in subsurface burrows may inhale volatile pollutants that are evaporated out of the soil as a vapor. This pathway is likely to be significant only in those cases where poor ventilation allows vapors to collect and concentrate and where the receptor spends a lot of time (e.g., when nesting) in such a poorly ventilated space. There is, however, little information available about how to quantify this exposure pathway. Small mammals are more likely to be significantly exposed to pollutants that have been taken up in their food items (e.g., plants, soil invertebrates) or through incidental ingestion of polluted soil particles. 

Because few regression models are available for energetic compounds and paired data are limited, soil to invertebrate bioaccumulation models used to estimate uptake in food items for energetic compounds are estimated from the Kow [56], Thus, concentrations of energetic compounds in earthworms are assumed to be a function of partitioning between the soil water and the earthworm tissues. This approach was used to derive the earthworm median BAF for RDX (9.91) and TNT (19.57) using the RDX (0.87) and TNT (1.6) Kow values, and the following bioaccumulation model BAF = 10(log Kow - 0.6)/[foc x 10(0.983 log Kow + 0.00028)]. 

Although there is a considerable amount known about the effects of prey chemicals on predator feeding preferences, much less is known about the proximate or ultimate reasons why marine invertebrates avoid certain compounds. Even when compounds cause behavioral avoidance of a food, few studies have assessed how consumption of prey secondary metabolites affects the physiology (and ultimately the fitness) of invertebrate consumers. Two basic approaches have been used (1) comparing effects of natural prey items which naturally contain or lack various secondary metabolites, or (2) comparing the effects of artificially prepared diets with and without metabolites. Studies of the first group108 109 have been able to correlate metabolite presence with certain effects on consumers, but the effects of secondary metabolites are confounded by other traits (e.g., protein,... 

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