Our Results

Mating between sterile females and wild males result in zero offspring while mating between sterile males and wild females may result in viable offspring. However, the latter is usually males which is sterile. In this way less and less successful matings will take place, resulting in the total collapse or decline of the wild population.

In less than 10 years, the sterile insect release program in Citrusdal significantly reduced the wild population, leading to less fruit infestation, better healthier crops with higher yields and the use of fewer pesticides.



Commercial releases are also done on various deciduous varieties and pomegranates, with excellent results.

Trials in other citrus areas in South Africa have been conducted, specifically in the Letsitele areas, with the aim of expansion to those areas as soon as possible.

Further expansion into other varieties affected by FCM in Southern Africa.

Possible alliances with the producers of other sterile insects that are a commercial pest.



The area-wide release of sterile T. leucotreta had encouraging effects on combating wild FCM as an increasing amount of sterile male moths were trapped from 2007 up to date. Trap catches of wild male moths declined from 13.0 moths per trap prior to sterile moth releases in 2006 to 0.3 wild moths per trap in 2016. The average pre-SIT fruit damage of 30 oranges per tree was documented during 2006-7 in the region scheduled for SIT introduction the following season. Fruit infestation by T. leucotreta decreased to 0.02 infested fruit per tree in 2016.


Numbers of wild T. leucotreta adults gradually declined to 0.1 wild males per trap in 2016 while infested fruit per tree declined to 0.02 infested fruit per tree. The increase in average number of trapped wild males in 2013-14 was due to additional zones being added to the SIT program. Orchards in these additional zones were historically more exposed to T. leucotreta infestation.


Traditionally, the natural T. leucotreta population is lower in this valley causing less crop losses. This was confirmed by the considerable lower average numbers of wild males trapped during the first season of sterile moth releases in comparison to the Elephants River Valley and the Sundays River Valley. Consequently, wild moth and infested fruit records were already low after the first release of sterile moths in 2014-15. In the following season, wild males were suppressed to the extent that no infested fruit were recorded for the entire season.