Turning Ultraviolet Light Traps On and Off Increases Their Attraction to House Flies (Diptera: Muscidae).

Pairs of electrocutor-grid ultraviolet light traps were assigned to three treatments to evaluate the effects of illumination events, e.g., light traps turned on, on house fly, Musca domestica L., attraction as indicated by numbers of flies captured by the traps. Both traps in treatment 1 were illuminated constantly (no illumination event). Both traps in treatment 2 were turned on, illuminated for 1 h, then turned off for 1 h, then repeated (1 illumination event every 2 h). Traps in treatment 3 were operated singularly. One trap was turned on for 1 h, then turned off. As it turned off, the other trap turned on for 1 h, then turned off, then repeated (1 illumination event every hour). The mean number of flies attracted per trap pair was significantly greater in treatment 1 than in treatments 2 or 3. However, in treatment 3, with one trap illuminated at a time and hourly illumination events, the mean fly catch was just 27% less, numerically, than the mean number of flies attracted to treatment 1 with both traps illuminated constantly. The effects of intermittent lighting and its potential use are discussed.

Development of Spalangia cameroni and Muscidifurax raptor (Hymenoptera: Pteromalidae) on live house fly (Diptera: Muscidae) pupae and pupae killed by heat shock, irradiation, and cold.

The objective of this study was to evaluate the suitability of killed house fly (Musca domestica L) pupae for production of two economically important pupal parasitoids. Two-day-old fly pupae were subjected to heat shock treatments of varying temperatures and durations in an oven at >or=70% RH; exposure to temperatures of 55 degrees C or higher for 15 min or longer resulted in 100% mortality. Exposure to 50 degrees C resulted in 40 and 91% mortality at 15 and 60 min, respectively. All (100%) pupae placed in a -80 degrees C freezer were killed after 10-min exposure; exposure times of <5 min resulted in <21% mortality. Progeny production of Spalangia cameroni Perkins and Muscidifurax raptor Girault and Sanders (Hymeoptera: Pteromalidae) from pupae killed by heat shock or 50 kR of gamma radiation was not significantly different from production on live hosts on the day when pupae were killed. Freeze-killed pupae produced 16% fewer S. cameroni than live pupae and an equivalent amount of M. raptor progeny on the day when pupae were killed. When killed pupae were stored in freezer bags at 4 degrees C for 4 mo, heat-killed, irradiated, and freeze-killed pupae remained as effective for production of M. raptor as live pupae. Production of S. cameroni on heat-killed and irradiated pupae was equal to parasitoid production on live pupae for up to 2 mo of storage, after which production on killed pupae declined to 63% of that observed with live pupae. Production of S. cameroni on freeze-killed pupae was 73-78% of production using live pupae during weeks 2-8 of storage and declined to 41 and 28% after 3 and 4 mo, respectively. Killing pupae by heat shock provides a simple and low-cost method for stockpiling high-quality hosts for mass-rearing both of these filth fly biological control agents.

Optimum experimental designs for multinomial logistic models.

Multinomial responses frequently occur in dose level experiments. For example, in a study of the influence of gamma radiation on the emergence of house flies (Musca domestica L., 1758), three disjoint outcomes occurred: death before the pupae opened, death during emergence, and life after emergence. Although the flies are easy to breed, this sort of bioassay is, in general, very expensive since it requires the use of a gamma radiation source. Experiments therefore need to be designed to involve the minimum number of different doses. Here the theory of optimum experimental design is applied to provide efficient experiments to estimate the parameters of those multinomial logistic models that are a special case of the multivariate logistic models of Glonek and McCullagh (1995, Journal of the Royal Statistical Society, Series B 57, 533-546). The purpose is to reduce the overall experimental cost. The general equivalence theorem (Fedorov, 1972, Theory of Optimal Experiments) is adapted to this class of models, providing an effective method of generating and checking the optimality of designs. One example on flies demonstrates the method, which can be easily implemented.

DNA oxidative damage and life expectancy in houseflies.

The objective of this study was to explore the relationship between oxidative molecular damage and the aging process by determining whether such damage is associated with the rate of aging, using the adult housefly as the experimental organism. Because the somatic tissues in the housefly consist of long-lived postmitotic cells, it provides an excellent model system for studying cumulative age-related cellular alterations. Rate of aging in the housefly was manipulated by varying the rate of metabolism (physical activity). The concentration of 8-hydroxydeoxyguanosine (80HdG) was used as an indicator of DNA oxidation. Exposure of live flies to x-rays and hyperoxia elevated the level of 8OHdG. The level of 8OHdG in mitochondrial as well as total DNA increased with the age of flies. Mitochondrial DNA was 3 times more susceptible to age-related oxidative damage than nuclear DNA. A decrease in the level of physical activity of the flies was found to prolong the life-span and corresponding reduce the level of 8OHdG in both mitochondrial and total DNA. Under all conditions examined, mitochondrial DNA exhibited a higher level of oxidative damage than total DNA. The 8OHdG levels were found to be inversely associated with the life expectancy of houseflies. The pattern of age-associated accrural of 8OHdG was virtually identical to that of protein carbonyl content. Altoghether, results of this study support the hypothesis that oxidative molecular damage is a causal factor in senescence.

Aging and protein oxidative damage.

The hypothesis that aging is associated with the accumulation of oxidative damage was tested in the adult male housefly by monitoring the loss of membrane protein -SH groups, and activities of glucose-6-phosphate dehydrogenase and alcohol dehydrogenase, the cytosolic enzymes that are particularly susceptible to oxidative damage. Membrane protein -SH content and activities of these enzymes decreased with age and were correlated with the life expectancy or physiological age rather than the chronological age of the flies. Because the experimentally-induced loss of membrane protein -SH groups has a demonstrable deleterious effect on a variety of cellular functions, such damage during aging can be hypothesized to contribute to the physiological attrition associated with senescence.

Relationship between aging and susceptibility to protein oxidative damage.

The objective of this study was to determine if the susceptibility of tissues to experimental oxidative damage is altered during the aging process. Adult houseflies were X-irradiated at different dosages, when they had reached 0.25 and 0.70 of their average life expectancy. Protein carbonyl content and activity of glucose-6-phosphate dehydrogenase were used as indices of oxidative damage. Fly homogenates as well as the live flies were more susceptible to oxidative damage at the older than at the younger age.

A light-sensitive yellow ommochrome pigment from the house fly.

A light-sensitive pigment (lambda max at 430 and 340 nm), extracted in acidic methanol from the Musca domestica heads, showed, in the absorption curve, a plateau at 480-500 nm and a new maximum at 400 nm, after visible light irradiation. The light-sensitive house fly pigment showed spectroscopic and chemical properties of the ommochrome pigments (Butenandt and Schäfer: Recent Progress in the Chemistry of Natural and Synthetic, Colouring Matters and Related Fields, Academic Press, New York, pp 13-33, 1962; Bolognese and Scherillo: Experientia 30:225-226, 1974). The treatment of the extracted pigment with a methanol-HClsat. mixture afforded some coloured compounds; two main products were identified by comparison of their chromatographic and spectral properties with authentic samples of 1-oxo-2H-3-carbomethoxy-5-methoxy-11-(fumaroyl-methylester)-pyrido [3,2-a] phenoxazine (compound 7) and 1-oxo-2H-3-carbomethoxy-5-methoxy-9-chlorine-11-(fumaroyl-methylester )-pyrido [3,2-a] phenoxazine (compound 8), obtained from the oxidation mixture of 3-hydroxykynurenine methylester (compound 9).

Relationship between gamma-irradiation, life span, metabolic rate and accumulation of fluorescent age pigment in the adult male housefly, Musca domestica.

The patterns of fluorescent age pigment (FAP) accumulation in response to gamma-irradiation were examined in adult male houseflies under conditions of relatively high and low levels of physical activity. Flies were exposed to 0, 20, 40, and 66 kR and their level of physical activity was altered by permitting or restricting flight activity. Under conditions of high activity the mean life span of flies exposed to 20 kR and 40 kR was greater than in the controls. The mean life span of high activity flies exposed to 66 kR and all groups of low activity irradiated flies was less than the control life span. The force of mortality as indicated by Gompertz slope was greater in high activity controls than in unirradiated flies maintained under low activity conditions. Gompertz slope was similar in corresponding high and low activity groups exposed to radiation. Radiation decreased the rate of FAP accumulation in high activity groups, but increased the rate of FAP accumulation under low activity conditions. The low activity control and low activity flies exposed to 20 kR had a lower FAP accumulation than the corresponding high activity groups at 14 days of age. At this age, low activity groups of flies exposed to 40 kR and 66 kR had concentrations of FAP that were similar to the corresponding high activity groups. These results indicate that radiation exposure decreased longevity by causing damage rather than by increasing the rate of aging.

Illumination induces dye incorporation in photoreceptor cells.

Illumination of fly photoreceptors in the presence of the fluorescent dye Lucifer yellow initiates incorporation of the dye, which stains each cell down to its synaptic terminal. Unilluminated cells do not become stained. Experiments on animals in vivo show that selected cells can be stained without loss of viability. "Induced endocytosis" provides a plausible mechanism underlying this phenomenon.

Life-lengthening effects of gamma-radiation on the adult housefly, Musca domestica.

Effects of gamma-irradiation on the life span of the adult housefly (Musca domestica) were examined in order to elucidate the relationship between metabolic rate, irradiation and longevity. Adult houseflies of both sexes, exposed to 0, 20, 40 and 66 kR of gamma-radiation, were housed under conditions of relatively high or low physical activity. The mean longevity of high activity males exposed to 20 and 40 kR exhibited a significant increase, whereas the average life span of all female populations, low activity males, and high activity males exposed to 66 kR was significantly decreased following irradiation. Radiation exposure caused a reduction in the rate of oxygen consumption in both sexes as well as a decrease in the incidence of wing loss in the male flies. Analysis of the results suggests that radiation-induced life-lengthening in the housefly is a consequence of reduced metabolic activity.

Influence of caffeine on sparing effect of dose fractionation in housefly larvae.

Caffeine, given during interfraction interval, abolishes the sparing effect of dose fractionation observed for delay of pupariation in Musca domestica larvae. When given as postirradiation treatment after single exposure, caffeine increases the delay in the synergistic manner. Pretreatment of the larvae with ascorbic acid for 3 h protects from radiation-induced delay whereas pretreatment with caffeine does not have any effect. Combination of ascorbic acid and caffeine pretreatment protects the larvae only at low concentration (0.05%) and not at high concentration (0.1%).

Irradiation-induced changes in circadian DDT-susceptibility and metabolic rhythms in the housefly.

The diel pattern of susceptibility to DDT of houseflies, reared under LD 14 : 10, was shown to be affected by 10 Krads of gamma radiation administered at the pupal stage. An additional peak in susceptibility of the flies to DDT corresponded to the time of irradiation of the pupae. Irradiated flies had higher general LD50 values than untreated flies. Flies reared in darkness demonstrated no discernable group rhythm apart from an altered susceptibility at the pupal irradiation time. Respiration rates of irradiated flies were slightly lower than the control flies and did not change at the time of irradiation. Groups of flies reared in darkness have no significant respiration rhythm.