Determination of Insecticide Application Time in Alfalfa Crops AgainstSitona Humeralis Stephens, Based on its Biology and Ethology

ABSTRACT

Sitona humeralis (S.) is the most dangerous insect in the Mediterranean region, which infests Medicago sativa, causing a considerable loss of the final produce. In the last years, surveillance of S. humeralis adults took place by means of scanning sampling in alfalfa fields and probable aestivation sites in Northern, Central and Northwestern Greece. The insect was found to aestivate either in mountainous regions or in regions situated near lakes, rivers or the sea, where the temperatures are lower than those in the fields, attacking mainly natural meadow plants. The insect's migration is due to the need of this period in order to give the eggs the time necessary to mature inside the ovarian tubes. In the alfalfa fields, the greatest number of adults collected was recorded from March to June and in September up to November when the adults mated and oviposited, with a peak in October; in the aestivation sites this happened during the hot months July and August. The findings of the present work permit us to define the timing for the application of control measures against S. humeralis in the alfalfa fields.

Keywords:

• insect migration
• timing for the insecticide application
• aestivation sites
• Curculionidae
• mitochondrial DNA