Bernard Greenberg

Interaction between Chrysomya rufifacies and Cochliomyia macellaria (Diptera: Calliphoridae): the possible consequences of an invasion.

Four Old World blow flies (Diptera: Calliphoridae), Chrysomya albiceps (Wiedemann), C. putoria Wiedemann, C. megacephala (Fabricius), and C. rufifacies (Macquart), have recently invaded the New World. The interaction of Chrysomya rufifacies (Macquart) with native carrion flies in Texas, USA, was investigated by reducing oviposition by the invader on rabbit carcasses outdoors. These carcasses produced significantly more Cochliomyia macellaria (Fabricius) adults compared to carcasses on which the invader was not reduced. The results suggest that C. macellaria populations will decline where the two species co-occur. They also support the hypothesis that the carrion community is saturated with species, and provide a mechanism for the possible elimination of Lucilia caesar (Linnaeus) in Madeira and the reduction of C. macellaria in South America by Chrysomya albiceps (Wiedemann).

The effect of killing and preservative solutions on estimates of maggot age in forensic cases.

Length of the oldest maggots recovered from a body often provide an accurate estimate of the time since death. The length of maggots of Protophormia terraenovae (Robineau-Desvoidy) of known age, at peak of feeding, was measured after 5 days immersion in one of 15 killing and preservative solutions, some of which are routinely used at autopsy and in forensic entomology; controls were killed in boiling water. There was shrinkage in all 15 solutions which translated into an underage error of 9.7 h in 70% ethanol, 11 h in San Veino and 16.8 h in formalin. Larvae of Calliphora vicina (Robineau-Desvoidy) underwent even greater shrinkage, which resulted in an underage error of 19.2 h in 70% ethanol, 26.4 h in formalin and 28.8 h in San Veino. Young third instar larvae underwent more shrinkage than older ones, with underage errors (in hours) as follows: P. terraenovae-70% ethanol 24 and San Veino, 24; C. vicina-70% ethanol, 7.2 and San Veino, 14.4. Maggots killed in boiling water and then placed in preservative solutions did not shrink. Length of the crop, which may be useful in age estimates of postfeeding larvae, was not altered significantly for forensic purposes in these solutions. The highly significant alterations in maggot length underscore a need for standardization in the treatment of maggots collected at the crime scene and at autopsy if their length is to be interpreted in a valid and consistent way. Recommendations are made for treatment of maggots wherever they are collected.

Resource use by an introduced and native carrion flies.

The carrion fly Chrysomya rufifacies has recently been introduced to North America. Larvae of this species are facultative predators on other carrion larvae, and are known to reduce populations of the New World fly Cochliomyia macellaria in the laboratory and in certain field situations. In order to identify conditions under which native taxa might avoid interaction with the invader, we examined broad patterns of resource use by capturing postfeeding larvae as they left a carcass. The Calliphorinae were least similar to C. rufifacies since they were able to exploit smaller carrion, showed a peak in density during cold weather while C. rufifacies numbers were low, and occurred much earlier than the invader during succession within a carcass. Phormia regina also was most abundant during cold weather. The Sarcophagidae were able to exploit smaller carcasses than the invader but are likely to encounter it in larger carcasses. C. macellaria was the species most similar to C. rufifacies in carrion use, and probably is reduced in number by the invader wherever they coexist. In contrast to all other taxa, C. rufifacies exited a carcass alone, suggesting that other larvae of the same age were attacked. Manipulation of a conspicuous predator, the ant Solenopsis invicta, revealed a negative effect on numbers of P. regina and C. macellaria.

Salmonella in the American cockroach: evaluation of vector potential through dosed feeding experiments.

Restrained American cockroaches, Periplaneta americana L., were fed graded doses of Salmonella typhimurium ranging from 1-6 X 10(3) to 2-0 X 10(6), and their faeces assayed daily for the pathogen. Only 4 specimens out of 117 demonstrated multiplication of salmonellas, which was unrelated to size of input. When data of persistence regardless of actual numbers were expressed as percentage Salmonella-positive faecal-days, and these transformed to probits, a graph of percentage-positive faecal-days versus log dose allowed a calculation of the CD 50, or contaminative dose required for 50% of the faecal-days to be infective. The CD 50 for this cockroach species was 1-4 X 10(6) Salmonella.

Factors in Phoretic Association of a Mite and Fly

Combined rearing of the mite Myianoetus muscarum (L.), and the fly Muscina stabulans (Fall.) has revealed adaptations of the hypopus to a series of fly factors. These adaptations favor the mites dispersal. Hypopi are attracted to the pupa by a volatile substance and cluster on the anterior end, from which the fly emerges.

Effects of antibiotics on the survival of Salmonella in the American cockroach.

The faecal survival of Salmonella typhimurium orally administered to restrained American cockroaches maintained on an antibiotic diet was investigated. Significant reductions in median numbers of total aerobic faecal microorganisms were noted in insects fed antibiotics daily, and when Salmonella was introduced to this modified micro-environment, it persisted for 44 days in all specimens. Multiplication of the pathogen was also observed in these insects, with numbers often exceeding 10(3) times that of the initial input. This differs significantly from our previous results showing that the pathogen is unable to multiply in conventional cockroaches. Attempts to restore the normal flora by feeding a faecal suspension from untreated cockroaches resulted in a decrease in numbers of Salmonella excreted, but did not result in their elimination. Carcasses of infected cockroaches retained viable Salmonella for at least 60 days post mortem, or 104 days after the infective meal.

Metabolic rates in five animal populations after prolonged exposure to weak extremely low frequency electromagnetic fields in nature.

Five species of soil-dwelling animals were collected under or some distance from the Navys Project Sanguine extremely low frequency experimental antenna in September 1974 and in summer 1975, and their oxygen consumption and respiratory quotient (RQ) were tested and compared. The species were: earthworms, Lumbricus terrestris L. and Lumbricus rubellus Hoffmeister; slug, Arion sp.; wood louse, Oniscus asellus L.; and redbacked salamander, Plethodon cinereus cinereus (Green). Controls were collected on the same or next day, 6 to 13 miles from the nearest antenna. Test and control animals were tested simultaneously. In September 1974 there were no significant differences in O2 consumption and RQ, except for a marginal difference (0.05 > P > 0.025) in O2 consumption of L. rubellus; in 1975, there were no significant differences. Comparisons of metabolic rates between exposed and control groups in fall 1974 and between fall and summer (1973 and 1975) populations show no seasonally linked change in sensitivity ...

Extremely low frequency antenna operation: Tests for possible impact on five naturally exposed animal populations

Wood lice, Oniscus asellus, earthworms, Lumbricus terrestris and Lumbricus rubellus, slugs, Arion sp., and red-backed salamanders, Plethodon cinereus cinereus, were collected under the Sanguine test facility antenna during summer 1972 and 1973 and their O2 consumption and RQ were compared with controls collected on the same day, 6–13 miles from the nearest antenna. In 1972 there were no significant differences in O2 consumption in four groups of test and control animals and marginal significance (P < 0.05) in wood lice; there were no significant differences in RQ of any group. In 1973, there were no significant differences in the O2 consumption and RQ of all five groups.

Magnetic Effects on Lower Organisms

Bacteria that orient and swim in a preferred direction in magnetic fields have been observed in diverse aquatic environments.1 These magnetotactic bacteria include a variety of morphologically distinct forms. Kalmijn and Blakemore2 found that these bacteria orient in uniform magnetic fields of about 0.5 G. Reversal of the geomagnetic field with Helmholtz coils caused the swimming bacteria to turn around in large U-turns and swim in the opposite direction. Killed bacteria also orient to align with imposed magnetic fields. Richard Blakemore