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Wind-tunnel studies on the collection of airborne spray droplets by flying locusts

Published online by Cambridge University Press:  19 September 2011

Frank Ndayanbo-Mugisha
Frank Ndayanbo-Mugisha
Affiliation:
International Red Locust Control Organization for Central and Southern Africa, P.O. Box 240252, Ndola, Zambia
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Abstract

In view of the present environmental awareness, the reduction of spray wastage, which in turn lessens environmental contamination, can be achieved by reducing spray volumes and improvement on spray efficiency through the use of correct ranges of spray droplet sizes. Published data on droplets collected by some insects consistently suggest that the optimum droplet sizes lie below 60 μm.

An experiment was conducted in a wind-tunnel to assess the locust collection efficiency when subjected to a spectrum of droplet size ranges with a view to determine the optimum droplet size.

Locusts were induced to fly in a wind-tunnel and then exposed to spray droplets which were produced by a spinning disc atomiser. Droplets collected on antennae, head, abdomen, legs and wings were sized and counted. The collection efficiency at wind-speeds ranging from 2 m/sec to 6 m/sec was calculated for the different body parts in the droplet size range 10–40, 40–60 and 60–80 μm. The calculated collection efficiency for the 10–40 μm size range was comparatively higher for all locust body parts.

Résumé

A la lumiére de l'actuelle prise de conscience en matiére d'environnement, une diminution de résidus d'aérosols qui, à son tour minimise la contamination de l'environnement peut s'obtenir avec la réduction des volumes de l'aérosol et l'amélioration de l'efficacité d'atomisation à travers l'emploi de gouttelettes atomisables d'une certaine taille. Des données publiées sur les particules atomisées qui sont collectées par certains insectes suggérent de toute évidence que les tailles optima de gouttelettes se situent en dessous de 60 μm.

Dans le but de déterminer cette taille optimale de gouttelettes, une expérience a été menée dans un tunnel aérodynamique pour évaluer l'efficacité de leur collection par le criquet. Cela a consisté à soumettre ce dernier à un éventail de tailles de gouttelettes atomisées.

Les criquets auxquels on a permis de voler dans le tunnel aérody namique ont ensuite été exposés aux gouttelettes produites par un disque atomiseur tournoyant. Des particules atomisées recoltées au niveau de l'antenne, de la tête, de l'abdomen, des membres et des ailes ont été clasées et comptées. L'efficacité de collection avec un soume de vent regié à des vitesses variant entre 2 m/sec et 6 m/sec a été calculée pour les différentes parties du corps, avec des gouttelettes ayant des tailles de 10–40, 40–60 et 60–80 μm. L'efficacité de collection pour la taille de 10–40 μm était comparativement plus élévée pour toutes les parties du corps du criquet.

Keywords

Locustbody partswind-tunnelspray dropletsimpactioncollection efficiencyoptimum droplet sizesCriquetparties du corpstunnel aérodynamiquegouttelettes d'aérosolrévélateur d'impactefficacité de collectiontailles optima de gouttelettes
Type
Research Articles
Information
International Journal of Tropical Insect Science , Volume 15 , Issue 2 , April 1994 , pp. 215 - 222
Copyright
Copyright © ICIPE 1994

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