Mosquito Handling, Transport, Release and Male Trapping Methods

Among the major vectors of human diseases, mosquitoes are the most devastating ones. In addition, urbanisation, globalisation and climate change have further accelerated the spread and outbreaks of new mosquito borne diseases. In view of the problems associated with conventional mosquito control, such as resistance and health effects, during a Thematic Plan Meeting held in Vienna in June 2014, experts concluded that there is an urgent need to develop new or complementary control techniques, including the Sterile Insect Technique (SIT), for major disease-transmitting mosquito species.

The Sterile Insect Technique (SIT) is an increasingly important component of area-wide integrated pest management (AW-IPM) programmes with great potential also for use against key insect vectors such as mosquitoes. With the toll of vector-borne diseases on human health and mortality increasing year on year, there have been recurring requests from Member States to develop tools and techniques for mosquito SIT to be able to apply the SIT to control mosquito vector populations (Resolution GC(52)/RES/13). The SIT has the ability to suppress, or in specific situations to eradicate existing vector populations and to prevent the establishment of new outbreaks.

Operational use of the SIT against other insect pests continues to reveal areas where new technologies could further improve efficiency and thus lead to more efficacious programmes. In addition to the mosquito SIT package which is being developed by the IPCL, the technologies must be in place for application on an operational level. Key issues to be resolved are handling, transport to the release location and actual release of sterile males without causing significant impact to their survival or post-release performance, as well as a means to monitor their performance after release. Methods for population surveillance of male mosquitoes is also important so that the releases can be scaled to the target population, and in order to enable the progress and impact of the SIT programme to be assessed.

An SIT programme at an operational scale will require several million adult male mosquitoes to be transported to release sites, likely after first being chilled for easy handling, with minimal detrimental impact on the quality and sexual capacity. Some means to transfer adult mosquitoes from emergence cages into temperature controlled containers for transport and ideally for release, is required, as well as the ability to maintain a cold chain between the rearing facility, or an emergence centre, and the release site. The scope of this CRP will include all steps of handling and transportation after the irradiation of mosquito pupae, including the containers and cooling systems, and biological requirements for chilling mosquitoes at sufficiently high densities without impacting survival or performance. Transport of chilled pupae and adults by road and by air should all be considered. The CRP will consider ground release and release from light aircraft, which may be required for certain circumstances, but the focus will be on release from small unmanned aerial vehicles. Again cooling methods will be considered, and the quality of released males is a key concern.

Alongside release methodologies, affordable and efficient trapping and other information collecting devices for field surveillance of the male population are needed prior to, during and following release to improve the evaluation of suppression programmes. Whereas the focus in the past has been on trapping females as the vectors of pathogens, male-specific surveillance will enable programmes to measure male quality, programme progress, and allow necessary adjustments to be made to operational activities. Specific techniques may be needed for surveillance of different species, or in different environmental settings, and so a variety of male-specific or male-targeted trap designs, attractants, automated surveillance tools, and the conservation of samples between trapping and laboratory analysis will all be considered. Although several good solutions are available now for validation and use in project sites, particularly for Aedine mosquitoes, no good options for reliably surveying and trapping Anophelines are currently available.

Although precise details of release methods will likely be fine-tuned for different species, the technology developed in this CRP should be generally applicable to all species. In addition, though the intention of the CRP is to provide technical advances to support the use of the SIT against mosquitoes, the same or very similar techniques will be of value to other genetic control programmes which rely on the release of mosquitoes.

The CRP will mainly focus on the following specific research objectives:

  • To explore approaches to perform the necessary handling and transport of irradiated, sex-separated male mosquitoes to the site of release, with minimal impact on survival and quality of released insects, including consideration of pre-release nutritional conditions. A seamless transition of mosquitoes from production to release is desirable to minimise handling and resulting impact on quality
  • To explore approaches to releasing sterile male mosquitoes in a controlled, traceable and documented manner over a large area, with the ability to target specific areas, ensuring low mortality and high quality in released insects
  • To explore different monitoring systems for surveillance of the target population of an AW-IPM programme with an SIT component, and to follow the performance of released males and the efficacy of population suppression

Participants:

Twenty one participants, from Australia, Brazil, Burkina Faso, China, France, French Polynesia, Germany, Indonesia, Italy, Mauritius, Mexico, Philippines, Senegal, South Africa, Spain, Sweden, Thailand, United Kingdom, United States of America.

Reports:

  • Report of the First Research Coordination Meeting [pdf], Vienna, Austria, November 2015.

Project Officer:

Jeremie Gilles and Rosemary Lees