Flight and settling behaviour of<i>Rhopalosiphum Padi</i>(L.) (Hemiptera: Aphididae)

AbstractAlate exules ofRhopalosiphum padi(L.) were flown in a flight chamber for three different flight times: 1 min, 5 min and 25 min. The rate of climb was recorded continuously during flight. Afterwards, the aphids were forced to land on either wheat or potato and settling behaviour was recorded. The settling response was strengthened with increasing flight time on both plants. The aphids spent more time walking and made more probes on potato than on wheat after 25 min of flight. The rate of climb was the same immediately before landing as immediately after a spontaneous re-take-off, except after a 25-min flight and landing on potato when the rate of climb was significantly higher after re-take-off. Comparison withAphis fabaeScop. from other investigations showed that the change in settling response with flight time was similar for the two species.R. padiseemed less able to discriminate rapidly between host and non-host plants thanA. fabae. It is concluded that its behaviour does not hinderR. padifrom being a vector of stylet-borne potato viruses.</jats:p

Desert locust control in ecologically sensitive areas: Need for guidelines.

Chemical control of desert locust (DL) is carried out over large areas of land, covering a range of different landscapes and ecosystems. There are no real restrictions for spraying in or close to environmentally sensitive areas and awareness of sensitivity is not always obvious to the people involved in control. However, concern about environmental issues in connection with DL control is growing and clear guidelines are needed. The objectives were: to identify and delineate areas particularly sensitive to pesticide contamination in northeastern Africa, e.g. protected areas, wetlands, populated places, oases, and areas with concentrations of migratory birds. These areas were matched with actual DL control during 1986-1998. The conclusion is that chemical control occurred in environmentally sensitive areas especially wetlands, e.g. temporary waters and mangroves; close to human settlements; and, to some extent, in or near protected areas and areas with numerous migratory birds