Analysis of body condition indices reveals different ecotypes of the Antillean manatee.

Assessing the body condition of wild animals is necessary to monitor the health of the population and is critical to defining a framework for conservation actions. Body condition indices (BCIs) are a non-invasive and relatively simple means to assess the health of individual animals, useful for addressing a wide variety of ecological, behavioral, and management questions. The Antillean manatee (Trichechus manatus manatus) is an endangered subspecies of the West Indian manatee, facing a wide variety of threats from mostly human-related origins. Our objective was to define specific BCIs for the subspecies that, coupled with additional health, genetic and demographic information, can be valuable to guide management decisions. Biometric measurements of 380 wild Antillean manatees captured in seven different locations within their range of distribution were obtained. From this information, we developed three BCIs (BCI1 = UG/SL, BCI2 = W/SL3, BCI3 = W/(SL*UG2)). Linear models and two-way ANCOVA tests showed significant differences of the BCIs among sexes and locations. Although our three BCIs are suitable for Antillean manatees, BCI1 is more practical as it does not require information about weight, which can be a metric logistically difficult to collect under particular circumstances. BCI1 was significantly different among environments, revealing that the phenotypic plasticity of the subspecies have originated at least two ecotypes-coastal marine and riverine-of Antillean manatees.

Volume of Larvae Is the Most Important Single Predictor of Mass Temperatures in the Forensically Important Calliphorid, Chrysomya megacephala (Diptera: Calliphoridae).

Calliphorid species form larval aggregations that are capable of generating heat above ambient temperature. We wanted to determine the relationship between volume, number of larvae, and different combinations of instars on larval mass heat generation. We compared different numbers of Chrysomya megacephala (F.) larvae (40, 100, 250, 600, and 2,000), and different combinations of instars (∼50/50 first and second instars, 100% second instars, ∼50/50 second and third instars, and 100% third instars) at two different ambient temperatures (20 and 30 °C). We compared 13 candidate multiple regression models that were fitted to the data; the models were then scored and ranked with Akaike information criterion and Bayesian information criterion. The results indicate that although instar, age, treatment temperature, elapsed time, and number of larvae in a mass were significant, larval volume was the best predictor of larval mass temperatures. The volume of a larval mass may need to be taken into consideration for determination of a postmortem interval.

Development of the Oriental Latrine Fly, Chrysomya megacephala (Diptera: Calliphoridae), at Five Constant Temperatures.

Chrysomya megacephala (Fabricius) is a forensically important fly that is found throughout the tropics and subtropics. We calculated the accumulated development time and transition points for each life stage from eclosion to adult emergence at five constant temperatures: 15, 20, 25, 30, and 35 °C. For each transition, the 10th, 50th, and 90th percentiles were calculated with a logistic linear model. The mean transition times and % survivorship were determined directly from the raw laboratory data. Development times of C. megacephala were compared with that of two other closely related species, Chrysomya rufifacies (Macquart) and Phormia regina (Meigen). Ambient and larval mass temperatures were collected from field studies conducted from 2001-2004. Field study data indicated that adult fly activity was reduced at lower ambient temperatures, but once a larval mass was established, heat generation occurred. These development times and durations can be used for estimation of a postmortem interval (PMI).

An automated approach to detecting signals in electroantennogram data.

Coupled gas chromatography/electroantennographic detection (GC-EAD) is a widely used method for identifying insect olfactory stimulants present in mixtures of volatiles, and it can greatly accelerate the identification of insect semiochemicals. In GC-EAD, voltage changes across an insect's antenna are measured while the antenna is exposed to compounds eluting from a gas chromatograph. The antenna thus serves as a selective GC detector whose output can be compared to that of a "general" GC detector, commonly a flame ionization detector. Appropriate interpretation of GC-EAD results requires that olfaction-related voltage changes in the antenna be distinguishable from background noise that arises inevitably from antennal preparations and the GC-EAD-associated hardware. In this paper, we describe and compare mathematical algorithms for discriminating olfaction-generated signals in an EAD trace from background noise. The algorithms amplify signals by recognizing their characteristic shape and wavelength while suppressing unstructured noise. We have found these algorithms to be both powerful and highly discriminatory even when applied to noisy traces where the signals would be difficult to discriminate by eye. This new methodology removes operator bias as a factor in signal identification, can improve realized sensitivity of the EAD system, and reduces the number of runs required to confirm the identity of an olfactory stimulant.

Thermoregulation in larval aggregations of carrion-feeding blow flies (Diptera: Calliphoridae).

The growth and development of carrion-feeding calliphorid (Diptera: Calliphoridae) larvae, or maggots, is of great interest to forensic sciences, especially for estimation of a postmortem interval (PMI). The development rate of calliphorid larvae is influenced by the temperature of their immediate environment. Heat generation in larval feeding aggregations (=maggot masses) is a well-known phenomenon, but it has not been quantitatively described. Calculated development rates that do not include internally generated temperatures will result in overestimation of PMI. Over a period of 2.5 yr, 80 pig, Sus scrofa L., carcasses were placed out at study sites in north central Florida and northwestern Indiana. Once larval aggregations started to form, multiple internal and external temperatures, and weather observations were taken daily or every few days between 1400 and 1800 hours until pupation of the larvae. Volume of each aggregation was determined by measuring surface area and average depth. Live and preserved samples of larvae were taken for species identification. The four most common species collected were Lucilia coeruleiviridis (=Phaenicia) (Macquart) (77%), Cochliomyia macellaria (F.) (8.3%), Chrysomya rufifaces (Macquart) (7.7%), and Phormnia regina (Meigen) (5.5%). Statistical analyses showed that 1) volume of a larval mass had a strong influence on its temperature, 2) internal temperatures of masses on the ground were influenced by soil temperature and mass volume, 3) internal temperatures of masses smaller than 20 cm3 were influenced by ambient air temperature and mass volume, and 4) masses larger than 20 cm3 on the carcass had strongly regulated internal temperatures determined only by the volume of the mass, with larger volumes associated with higher temperatures. Nonsignificant factors included presence of rain or clouds, shape of the aggregation, weight of the carcass, species composition of the aggregation, time since death, or season.

Species association among predaceous and phytophagous apple mites (Acari: Eriophyidae, Phytoseiidae, Stigmaeidae, Tetranychidae).

Predator-predator, predator-prey, and prey-prey associations among nine species of mites were studied in a plot of 100 'Red Delicious' apple (Malus pumila Miller) trees from 1990 to 1997. In 1990, seven-year-old trees were inoculated with Panonychus ulmi (Koch), Tetranychus urticae Koch (Acari: Tetranychidae) or both, and sprayed with azinphosmethyl (alone or plus endosulfan), or nothing. The species Zetzellia mali (Ewing) (Acari: Stigmaeidae), Amblyseius andersoni Chant (Acari: Phytoseiidae), Eotetranychus sp., Bryobia rubrioculus (Scheuten) (Acari: Tetranychidae), and Aculus schlechtendali Nalepa (Acari: Eriophyidae) were already present or immigrated into plots, and Galendromus occidentalis (Nesbitt) and Tvphlodromus pyri Scheuten (Acari: Phytoseiidae) were introduced. Yule's V association index was used to measure positive, neutral, or negative interspecific associations for each species pair, because of its robustness with spatially autocorrelated data. We found that pesticide and release treatments did not greatly affect the association results, but there were strong seasonal differences. Predator-predator associations were the strongest and most consistent, showing negative associations in the early and mid seasons, and neutral ones in late season. Negative associations of T pyri with other predators were the strongest, which is consistent with evidence that this mite can detect other predators on a leaf. Predatorprey seasonal associations were mixed, with some positive and others negative, with most significant associations occurring in the mid season. One prey-prey interaction was positive, again in mid season, most likely because of similar habitat preferences.

Effects of dietary oltipraz and ethoxyquin on aflatoxin B1 biotransformation in non-human primates.

Following aflatoxin B1 (AFB) exposure, rats readily develop liver tumors. However, treatment of rats with a variety of compounds, including the synthetic dithiolthione oltipraz and the antioxidant ethoxyquin, protects these rodents from AFB-induced hepatocarcinogenesis. Several epidemiological studies strongly suggest that AFB is also a causative agent of liver cancer in humans. However, relatively little is known about the efficacy of cancer chemoprevention in human and non-human primates. To this end, we examined the effects of chemopreventive agents on AFB metabolism in non-human primates. Hepatic aflatoxin B1 metabolism profiles of macaque (Macaca nemestrina) and marmoset (Callithrix jacchus) monkeys were determined and compared to humans. Quantitatively, the oxidative metabolism of this mycotoxin was similar in the three primate species. In contrast to macaques, both humans and marmosets lacked AFB-glutathione conjugating activity. It was concluded that marmosets resembled human AFB metabolism more closely than the macaques, and therefore, marmoset monkeys were chosen for this study. Eleven adult male marmosets were randomly assigned to three groups. Animals received the synthetic dithiolthione oltipraz, the antioxidant ethoxyquin, or vehicle only. In addition, two single doses of AFB were also administered orally before and after animals were treated with aforementioned compounds. Both oltipraz and ethoxyquin induced aflatoxin B1-glutathione conjugating activity in the livers of some but not all marmosets. In addition, 10 microM oltipraz inhibited cytochrome P450-mediated activation of AFB to the ultimate carcinogenic metabolite, aflatoxin B1-8,9-epoxide, in vitro, up to 51%. Furthermore, animals treated in vivo with oltipraz, but not ethoxyquin, exhibited a significant reduction (53% average) in AFB-DNA adduct formation relative to the control animals (p < 0.05). Together, our data suggest that chemoprevention is also effective in primates; however, most likely to a lesser degree than in rodents.

Human variability in hepatic glutathione S-transferase-mediated conjugation of aflatoxin B1-epoxide and other substrates.

Hepatic cytosolic fractions prepared from 14 human donors were analysed for glutathione S-transferase (GST) activity towards synthetic aflatoxin B1-8,9-epoxide (AFBO). In addition, GST-AFBO activity of pooled human liver cytosols was compared with rat, hamster, and mouse liver cytosol GST-AFBO activities. Consistent with previous studies, human liver cytosolic GSTs exhibited little activity towards AFBO. Hepatic GST-AFBO activities of rat, hamster, and mouse were 48-, 56-, and 312-fold greater, respectively, than observed for human liver using synthetic AFBO, and 70-, 465-, and 3545-fold greater, respectively, than observed for human liver using microsomally-generated AFBO. Furthermore, there was a 58-fold variation in hepatic GST-AFBO activities among the 14 human samples using synthetic AFBO as a substrate. Large interindividual variations were also observed with respect to GST activities towards bromosulfophthalein (BSP, 92-fold variation) and 3,4-dichloronitrobenzene (DCNB, 36-fold variation). Lesser interindividual variations were observed with respect to human liver GST activities towards benzo(a)pyrene-4,5-oxide (BaPO, 9-fold variation), 1-chloro-2,4-dinitrobenzene (CDNB, 8.5-fold variation), cumene hydroperoxide (CHP, 5-fold variation), and p-nitrophenyl acetate (NPA, 4-fold variation). No correlation was found among GST-AFBO activities and the presence of GST mu as determined by enzyme-linked immunosorbent assay (ELISA) or GST-trans-stilbene oxide (TSO) catalytic activity. Our observations support those of previous studies indicating that human liver cytosolic GSTs are relatively ineffective at conjugating AFBO. Furthermore, our data indicate that humans exhibit large inter-individual differences with respect to hepatic cytosolic GST conjugation of AFBO and certain other GST substrates.