Long distance transport of irradiated male Glossina palpalis gambiensis pupae and its impact on sterile male yield

Abstract

BackgroundThe application of the sterile insect technique (SIT) requires mass-production of sterile males of good biological quality. The size of the project area will in most cases determine whether it is more cost effective to produce the sterile flies locally (and invest in a mass-rearing facility) or import the sterile flies from a mass-rearing facility that is located in another country. This study aimed at assessing the effect of long distance transport of sterile male Glossina palpalis gambiensis pupae on adult male fly yield.MethodsThe male pupae were produced at the Centre International de Recherche-Développement sur l’Elevage en zone Subhumide (CIRDES), Bobo-Dioulasso, Burkina Faso, and shipped with a commercial courier service in insulated transport boxes at a temperature of ±10°C to Senegal (±36 h of transport). Upon arrival in the insectary in Dakar, the pupae were transferred to an emergence room and the flies monitored for 3–6 days.ResultsThe results showed that the used system of isothermal boxes that contained phase change material packs (S8) managed to keep the temperature at around 10°C which prevented male fly emergence during transport. The emergence rate was significantly higher for pupae from batch 2 (chilled at 4°C for one day in the source insectary before transport) than those from batch 1 (chilled at 4°C for two days in the source insectary before transport) i.e. an average (±sd) of 76.1 ± 13.2% and 72.2 ± 14.3%, respectively with a small proportion emerging during transport (0.7 ± 1.7% and 0.9 ± 2.9%, respectively). Among the emerged flies, the percentage with deformed (not fully expanded) wings was significantly higher for flies from batch 1 (12.0 ± 6.3%) than from batch 2 (10.7 ± 7.5%). The amount of sterile males available for release as a proportion of the total pupae shipped was 65.8 ± 13.3% and 61.7 ± 14.7% for batch 1 and 2 pupae, respectively.ConclusionsThe results also showed that the temperature inside the parcel must be controlled around 10°C with a maximal deviation of 3°C to maximize the male yield.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0869-3) contains supplementary material, which is available to authorized users.

Optimised conditions for handling and transport of male Anopheles arabiensis: effects of low temperature, compaction, and ventilation on male quality

“…Males were not held immobile for longer than 24 h. Thus, it remains to be seen whether they can endure 48 or perhaps 72 h without a significant subsequent impact upon quality. This temperature range is in line with the temperature used to maintain sterile Mediterranean fruit flies (Enkerlin, ) and tsetse flies (Pagabeleguem et al., ) during an aerial release (10 ± 3 °C). Similarly, the ladybug Coccinella magnifica Redtenbacher could be maintained for up to 30 h at 10 °C without any detrimental effect (Casada et al., ).…”

“…Sterile male tsetse pupae are transported at a temperature of around 8–10 °C (Pagabeleguem et al., ) to prevent emergence of the male flies during transport. In view of the slow reproductive cycle of tsetse flies, females need to be retained in the colony.…”

“…Furthermore, a suitable temperature range for transport of male mosquitoes was defined, and we showed that mosquitoes did not emit metabolic heat, whilst held in bulk in an immobile state. Sterile male tsetse pupae are transported at a temperature of around 8-10°C (Pagabeleguem et al, 2015) to prevent emergence of the male flies during transport. In view of the slow reproductive cycle of tsetse flies, females need to be retained in the colony.…”

“…Handling, sterilisation, immobilisation, transport, and release are all essential components of an SIT programme. However, each step, if not addressed correctly, could influence male mosquito survival and quality (Pagabeleguem et al, 2015). Because the SIT relies on sterile males competing for mates after release, this impact must be minimised to maximise the technique's efficacy.…”

Chilling, irradiation and transport of male Glossina palpalis gambiensis pupae: effect on the emergence, flight ability and survival.

“…At the CIRDES and SAS insectaries, pupae were collected daily at the completion of female emergence and immediately chilled at 4°C to prevent male emergence and irradiated under chilled conditions (4–6°C) [18]. The CIRDES pupae were irradiated in a 137 Cs source for 24 minutes and 30 seconds to yield a dose of 110 Gy.…”