Wild Male Flies Research Articles

Evaluating the Effect of Irradiation on the Densities of Two RNA Viruses in Glossina morsitans morsitans.

Tsetse flies are cyclic vectors of Trypanosoma parasites, which cause debilitating diseases in humans and animals. To decrease the disease burden, the number of flies is reduced using the sterile insect technique (SIT), where male flies are sterilized through irradiation and released into the field. This procedure requires the mass rearing of high-quality male flies able to compete with wild male flies for mating with wild females. Recently, two RNA viruses, an iflavirus and a negevirus, were discovered in mass-reared Glossina morsitans morsitans and named GmmIV and GmmNegeV, respectively. The aim of this study was to evaluate whether the densities of these viruses in tsetse flies are affected by the irradiation treatment. Therefore, we exposed tsetse pupae to various doses (0-150 Gy) of ionizing radiation, either in air (normoxia) or without air (hypoxia), for which oxygen was displaced by nitrogen. Pupae and/or emerging flies were collected immediately afterwards, and at three days post irradiation, virus densities were quantified through RT-qPCR. Generally, the results show that irradiation exposure had no significant impact on the densities of GmmIV and GmmNegeV, suggesting that the viruses are relatively radiation-resistant, even at higher doses. However, sampling over a longer period after irradiation would be needed to verify that densities of these insect viruses are not changed by the sterilisation treatment.

Determine the Gamma Radiation Technique to Sterilization of Insects from Risk Factor

The sterile insect technique (SIT) is an environment-friendly blighter management technique with application within the area-wide integrated management of key pests, together with the suppression or elimination of introduced populations and therefore the exclusion of recent introductions. Procreative sterility is often evoked by radiation, a convenient and consistent technique that maintains an inexpensive degree of aggressiveness within the discharged insects. The price and effectiveness of an effective program integration of the SIT rely on the balance between sterility and aggressiveness, but it seems that current operational programs with an associate SIT element aren't achieving an associated, applicable balance. In this paper, we will discuss how to improve the sterilization method as well as a simple model and procedure for determining the optimum dose. The work in the gift was focused on an association analysis of the electromagnetic wave technique for insect sterilization as a risk issue. Discharge of enormous numbers of gamma-radiated male flies over the complete island caused concern regarding sterilization as an attainable technique for the dominant insects' public health. Several studies on the sterilization of varied insect vectors of sickness have been conducted since then. The study's goal was to check if electromagnetic waves were an efficient insect management mechanism. Insect sterilization is commonly used to create safe environments for fruit homes, manage blighters, and avoid livestock health issues. The sterilization insect technique entails mass-rearing of the target species, sterilization of the male, and unharnessing in sufficient numbers to equal wild male flies in the natural environment. It's species-specific, with no results for any of the 'non-target' species.

A Molecular Method to Discriminate between Mass-Reared Sterile and Wild Tsetse Flies during Eradication Programmes That Have a Sterile Insect Technique Component.

BackgroundThe Government of Senegal has embarked several years ago on a project that aims to eradicate Glossina palpalis gambiensis from the Niayes area. The removal of the animal trypanosomosis would allow the development more efficient livestock production systems. The project was implemented using an area-wide integrated pest management strategy including a sterile insect technique (SIT) component. The released sterile male flies originated from a colony from Burkina Faso.Methodology/Principal FindingsMonitoring the efficacy of the sterile male releases requires the discrimination between wild and sterile male G. p. gambiensis that are sampled in monitoring traps. Before being released, sterile male flies were marked with a fluorescent dye powder. The marking was however not infallible with some sterile flies only slightly marked or some wild flies contaminated with a few dye particles in the monitoring traps. Trapped flies can also be damaged due to predation by ants, making it difficult to discriminate between wild and sterile males using a fluorescence camera and / or a fluorescence microscope. We developed a molecular technique based on the determination of cytochrome oxidase haplotypes of G. p. gambiensis to discriminate between wild and sterile males. DNA was isolated from the head of flies and a portion of the 5’ end of the mitochondrial gene cytochrome oxidase I was amplified to be finally sequenced. Our results indicated that all the sterile males from the Burkina Faso colony displayed the same haplotype and systematically differed from wild male flies trapped in Senegal and Burkina Faso. This allowed 100% discrimination between sterile and wild male G. p. gambiensis.Conclusions/SignificanceThis tool might be useful for other tsetse control campaigns with a SIT component in the framework of the Pan-African Tsetse and Trypanosomosis Eradication Campaign (PATTEC) and, more generally, for other vector or insect pest control programs.

Irradiated male tsetse from a 40-year-old colony are still competitive in a Riparian forest in Burkina Faso.

BackgroundTsetse flies are the cyclical vectors of African trypanosomosis that constitute a major constraint to development in Africa. Their control is an important component of the integrated management of these diseases, and among the techniques available, the sterile insect technique (SIT) is the sole that is efficient at low densities.The government of Burkina Faso has embarked on a tsetse eradication programme in the framework of the PATTEC, where SIT is an important component. The project plans to use flies from a Glossina palpalis gambiensis colony that has been maintained for about 40 years at the Centre International de Recherche-Développement sur l'Elevage en zone Subhumide (CIRDES). It was thus necessary to test the competitiveness of the sterile males originating from this colony.Methodology/Principal FindingsDuring the period January–February 2010, 16,000 sterile male G. p. gambiensis were released along a tributary of the Mouhoun river. The study revealed that with a mean sterile to wild male ratio of 1.16 (s.d. 0.38), the abortion rate of the wild female flies was significantly higher than before (p = 0.026) and after (p = 0.019) the release period. The estimated competitiveness of the sterile males (Fried index) was 0.07 (s.d. 0.02), indicating that a sterile to wild male ratio of 14.4 would be necessary to obtain nearly complete induced sterility in the female population. The aggregation patterns of sterile and wild male flies were similar. The survival rate of the released sterile male flies was similar to that observed in 1983–1985 for the same colony.Conclusions/SignificanceWe conclude that gamma sterilised male G. p. gambiensis derived from the CIRDES colony have a competitiveness that is comparable to their competitiveness obtained 35 years ago and can still be used for an area-wide integrated pest management campaign with a sterile insect component in Burkina Faso.

Factory Tsetse Flies Must Behave Like Wild Flies: A Prerequisite for the Sterile Insect Technique

Tsetse flies are the vectors of human and animal African trypanosomoses, the former a major neglected disease, and the latter considered among the greatest constraints to livestock production in sub-Saharan Africa. To date, the disease is mainly contained through the prophylactic and curative treatment of livestock with trypanocidal drugs, which is not sustainable. The removal of the vector, the tsetse fly, would be the most efficient way of managing these diseases. A number of efficient tsetse control tactics are available that can be combined and applied following area-wide integrated pest management (AW-IPM) principles [1]. The concept entails (1) the integration of various control tactics, preferably combining those methods that are effective at high population densities with those that are effective at low population densities to obtain maximal efficiency, and (2) the control effort is directed against an entire tsetse population within a delimited area. This is particularly relevant in case eradication is the strategy of choice. Genetic control tactics such as the sterile insect technique (SIT) show great potential for integration in such AW-IPM programmes because they are very efficient for controlling low-density populations, which is not the case for most other techniques. Sterile male insects are reared and, after sterilization with ionizing radiation, sequentially released in large quantities to outnumber the wild male flies. A mating of a sterile male with a virgin wild female fly results in no offspring. Recently, transgenic and paratransgenic techniques have been proposed to sterilize male insects or to make strains refractory to disease parasites in the case of vectors [2]–[4]. However, to ensure the success of these control methods, factory-reared tsetse flies must be competitive with their wild counterparts and must exhibit a similar behaviour in a natural environment.

Senescence: rapid and costly ageing in wild male flies.

Ageing (senescence) has never been demonstrated convincingly in any insect in the wild, where mean lifespans are probably much shorter than in the laboratory1, and most evidence for senescence in other wild animals (such as mammals) is limited to their reduced survival with age2. Here we show that ageing is detectable in wild populations of a very short-lived insect, the antler fly (Protopiophila litigata), and causes debilitating and costly effects that force a decline not only in survival probability, but also in the reproductive rate of males. Our findings argue against the possibility of a trade-off between fitness components, whereby survival may decline without senescence if investment in reproduction increases with age3, and indicate that ageing rates are subject to intense selection in the wild.

MATING AND REMATING OF MEDFLIES (DIPTERA: TEPHRITIDAE) IN GUATEMALA: INDIVIDUAL FLY MARKING IN FIELD CAGES

The sterile insect technique (SIT) depends critically upon the ability of sterilized, released males to locate and mate with wild females. The overall efficiency of the method also depends upon the relative frequencies of remating by wild females following first matings to laboratory or wild males. Using a newly devised technique that individually marks the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), a field cage study was undertaken in a Guatemala coffee orchard to record individual fly mating behaviors between each of several laboratory strain and coffee-reared wild flies. Five laboratory strains were tested - a genetic sexing strain examined in sex ratios between 50%-100% sterile males, two standard bisexual strains, and two F1 hybrid strains. The marking technique revealed a substantial amount of information on individual fly mating and remating. Wild male flies significantly outcompeted each of the lab strains in the first matings with both wild and lab females. Approx. 22% and 3% of wild males and females, respectively, remated in the field cages during two consecutive morning observation periods, while 4-8% of lab males, and 2-8% of lab females remated, respectively. Male flies from each lab strain averaged significantly shorter copulation times than wild males. Female flies, either lab or wild, tended to remate more often if they first mated to a lab male, but the differences were not statistically significant. An index was devised to provide a measure of relative male mating quality. Wild males tended to have higher individual index values than lab strain males. Average values of the latter ranged from ca. half to roughly equal that of wild males.

Mating-Induced Changes in Olfactory-Mediated Behavior of Laboratory-Reared Normal, Sterile, and Wild Female Mediterranean Fruit Flies (Diptera: Tephritidae) Mated to Conspecific Males

Laboratory-reared normal, sterile, and wild female Mediterranean fruit flies, Ceratitis capitata (Wiedemann), were mated with laboratory-reared normal, sterile, and wild male flies to assess the ability of males to alter olfactory-mediated behavioral responses of females to male-produced pheromone or host fruit odor. Virgin females of all 3 types showed a preferential attraction and arrestment on yellow spheres emitting male-produced pheromone in a laboratory flight tunnel. Laboratory-reared normal and wild females mated to laboratory reared normal, sterile, or wild males switched their behavior showing strong preferential attraction to, arrestment on, and egg-laying in (for laboratory-reared females) yellow spheres emitting host fruit odor (guava) over male-produced pheromone. Sterile females did not show a significant switch in behavior except when mated to sterile males. The olfactory-mediated behavioral switch was most evident in the laboratory-reared normal female × laboratory-reared normal male mating. These findings suggest that irradiation of males inducing gamete sterility does not affect the factor(s) from the male accessory gland associated with altering female olfactory behavior. The ability of sterile males to alter adequately olfactory-mediated behavior of wild females is discussed in the context of the sterile insect technique for control of Mediterranean fruit flies in the field.

Observations on sex attraction and mating behaviour of the tsetse flyGlossina morsitans orientalisVanderplank

Laboratory and field investigations into sex attraction and mating behaviour ofGlossina morsitans orientalisVanderplank have been described. Male flies were not attracted to volatile and soluble compounds from two- to three-day-old mature virgin females, or to virgin females in a simple olfactometer. Removal of antennae from either sex did not appreciably reduce insemination rates after 24–48-h mating periods compared with normal flies. Similar numbers of wild male flies were caught off oxen baited or non-baited with mature virgin females.G. m. orientalisprobably does not produce a pheromone.Male flies appeared to be sexually activated only after movement by the female. Mating success was reduced in the dark and when the male's eyes were painted, but blinding the female fly did not reduce insemination. Mating was similar with or without wings and halteres and the sounds produced by them.Time between pairing the sexes and the start of mating tended to increase, and the percentage of inseminated females accepting two or more matings decreased, after the first copulation. Female flies rarely re-mated within a day. Virgin female flies accepted males passively with partly open wings, and mated females rejected further copulation with closed wings, activity to shake the male off, and primarily a downward-curved abdomen. Virgin female flies mated for periods of 1–45 min did not receive sperm but successfulad libitummating was reduced a day later. Insemination rates decreased with females older than seven days and reached zero 28–83 days after eclosion, while 37-day-old males inseminated 93% of young females.