USE OF NITROGEN AND CHILLING IN THE PRODUCTION OF RADIATION‐INDUCED STERILITY IN THE TSETSE FLY GLOSSINA MORSITANS

Abstract

Male pupae of Glossina morsitans were irradiated at the very late pupal stage at which females had already emerged. By the use of nitrogen and/or cooling stimulated emergence from the treated pupae could be postponed for several hours after irradiation, which would be advantageous in a sterile male project. The male survival and fertility after various doses given in nitrogen or warm or cold air were compared and it was found that a specified level of fertility could be achieved with better survival if nitrogen was used rather than air. The likely population‐suppressing effect of releases of males after various possible treatments was computed, and it was concluded that a dose in nitrogen which gives incomplete sterility would be the most efficient. Zusammenfassung DER EINSATZ VON STICKSTOFF UND ABKÜHLUNG BEI DER ERZEUGUNG STRAHLENINDUZIERTER STERILITÄT BEI DER TSETSE‐FLIEGE, GLOSSINA MORSITANS Puppen von Glossina morsitans wurden zur Sterilisierung bestrahlt. Es wurde ein Zeitpunkt ausgewählt, an dem fast alle weiblichen Fliegen schon geschlüpft waren, so daß nahezu ausschließlich die Männchen bestrahlt wurden. Eine Bestrahlung bei 20° C stimulierte das Schlüpfen der Fliegen. Wurde die Bestrahlung dagegen bei + 2° in Luft oder Stickstoffatmosphäre vorgenommen, so konnte das Schlüpfen bis zum Wiedererwärmen verhindert werden. Diese Methode kann für Versuche im Freiland von großem Nutzen sein. Die Überlebens‐ und Sterilitätsrate wurden nach verschiedenen Bestrahlungsdosen in Stickstoffatmosphäre, in warmer oder kalter Luft verglichen. Wenn auch die Bestrahlung der Männchen vor dem Schlüpfen aus den Puppen mit einer bestimmten Dosis in Stickstoffatmosphäre zu einem geringeren Sterilitätsgrad führt, als die gleiche Bestrahlung in Luft, so liegt der Vorteil dieses Verfahrens jedoch in einer erheblich höheren Überlebensrate der sterilisierten Fliegen. Es kann damit jeder Sterilitätsgrad bei besserer Überlebensrate erzielt werden. Am rechnerischen Beispiel wird gezeigt, daß eine höhere Überlebensrate der sterilisierten Männchen für die Verminderung der Population von größerer Bedeutung ist, als der erzielte Sterilitätsgrad. Daher erscheint es günstiger, eine Bestrahlung in Stickstoffatmosphäre vorzunehmen.

Short-term anoxic conditioning hormesis boosts antioxidant defenses, lowers oxidative damage following irradiation and enhances male sexual performance in the Caribbean fruit fly, Anastrepha suspensa

“…By separating the effects of the anoxic conditioning from irradiation in nitrogen, we see that at higher doses there is a significant effect of irradiation in nitrogen beyond the effect of the anoxic conditioning. This is consistent with the idea that ROS are generated during irradiation from the splitting of gaseous oxygen and water (von Sonntag, 1987), and with the fact that irradiation in nitrogen increases survival (Curtis and Langley, 1972) and longevity (Zumreoglu et al, 1979). This increase in mortality can be directly attributed to irradiation in oxygen after the anoxia pre-treatment and can be avoided by irradiating these individuals in an oxygen-free environment.…”

Sex ratio distortion and semi-sterility in the progeny of irradiatedGlossina morsitans

“…(i) Sex-ratio distortion Table 1 shows data for various radiation treatments on the fertility of the irradiated males (from Curtis & Langley, 1972) and on the sex-ratio of the progeny fathered by them. The sex-ratio was significantly biased in favour of males in the total over all treatments and in the individual treatments in which the sample sizes were largest (Table 1).…”

“…The progeny of irradiated tsetse flies 157 sperm and since in G. morsitans there is, approximately, a 'one-hit' relationship of fertility to dose (Curtis & Langley, 1972) it is assumed that there would be a Poisson distribution of sperms with 0, 1, 2, ..., n dominant lethals. The observed proportions of surviving male and female zygotes therefore represent the term e~m, where m is the mean number of dominant lethals per sperm.…”

“…At Langford the dose rate was 150 rad/sec, treatment was at the late pupal stage and in some cases an atmosphere of nitrogen was used during treatment (Curtis & Langley, 1972). At Seibersdorf the dose rate was 100 rad/sec and treatment was at the early adult stage.…”

Genetic control of insect pests: growth industry or lead balloon?

“…as one raises the radiation dose to reduce residual fertility, so one may increase somatic debilitation of the males. In some species one can escape this problem by irradiation in an anoxic atmosphere, as the somatic effects of radiation are more strongly oxygen dependent than the genetic ones (Curtis & Langley, 1972).…”