Comments on: Keeping the number of blackflies down http://yaoundefoundation.org/?p=547 Public health and food production in Africa Fri, 29 Nov 2013 14:45:06 +0000 hourly 1 http://wordpress.org/?v=3.0.4 By: Didier Baleguel http://yaoundefoundation.org/?p=547#comment-5219 Didier Baleguel Fri, 29 Nov 2013 14:45:06 +0000 http://yaoundefoundation.org/?p=547#comment-5219 It is quite exact when you mentionned that where the river was treated, the number of flies generally decreased. But the main problem is still concerning the speed of reinfestation of the treated sites. The reinfestation is fast when the treated area is not extended down and uptream the main river (Sanaga River) nor when the tributaries are not treated at all. In fact, blackflies can fly to about 25 Km using their proper wings beat and up to hundreds kilometers under wind effect. But their concentrations in certain areas depend from the existence of favourable factors such as relative humidity or human concentrations, combined with existence of fly displacement corridors linked to the breeding sites line. Tributaries remain a major factor of blackfly reproduction due to numbers of breeding sites founded in some of them. So it is clearly indicated to extend the treated area not only down and upstream in the main treated river, but also in the tributaries identified as to be productive for blackflies. It is therefore necessary, while continuing good scientific monitoring of the blackfly control project as done by YIF, to have additionnal founds because the larvicides are not cheap! It is quite exact when you mentionned that where the river was treated, the number of flies generally decreased. But the main problem is still concerning the speed of reinfestation of the treated sites. The reinfestation is fast when the treated area is not extended down and uptream the main river (Sanaga River) nor when the tributaries are not treated at all.

In fact, blackflies can fly to about 25 Km using their proper wings beat and up to hundreds kilometers under wind effect. But their concentrations in certain areas depend from the existence of favourable factors such as relative humidity or human concentrations, combined with existence of fly displacement corridors linked to the breeding sites line. Tributaries remain a major factor of blackfly reproduction due to numbers of breeding sites founded in some of them.

So it is clearly indicated to extend the treated area not only down and upstream in the main treated river, but also in the tributaries identified as to be productive for blackflies.

It is therefore necessary, while continuing good scientific monitoring of the blackfly control project as done by YIF, to have additionnal founds because the larvicides are not cheap!

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