The effect of microfertilisers on the number of pollen beetles on spring oilseed rape
Maend, M.(Estonian Agricultural Univ., Tartu (Estonia))E-mail:[email protected] | Karise, R.(Estonian Agricultural Univ., Tartu (Estonia)) | Viik, E.(Estonian Agricultural Univ., Tartu (Estonia)) | Metspalu, L.(Estonian Agricultural Univ., Tartu (Estonia)) | Laeaeniste, P.(Estonian Agricultural Univ., Tartu (Estonia)) | Luik, A.(Estonian Agricultural Univ., Tartu (Estonia))
The pollen beetle (Meligethes aenus F.) is an important pest of spring oilseed rape (Brassica napus var. oleifera). Both Meligethes adults and larvae feed on pollen of oilseed rape. The beetles use olfactory and pollen odour cues to locate food resource. Here we report on pollen beetle responses to the pollen of oilseed rape fertilised with different microelements. The study was carried out in an experimental field near Tartu in July 2003. The field consisted of 36 plots (a 10 square m), which were treated with eight different microfertilisers (Micro Mo, NewRaps, Micro Mn, Micro Raps, HydroMag 300, Sulphur F3000, Micro B, Micro Cu). Each treatment was conducted in four replications. To quantify pollen availability, twelve flowers were collected randomly from each plot in the peak flowering of oilseed rape in mid-July. Pollen beetles were gathered by the shaking method. The mean number of pollen grains per flower depended significantly on the fertilising system and the pollen available in the flowers. The plots fertilised with sulphur, magnesium, copper and boron distinguished from all other variants by a higher number of pollen grains per flower. At the same time, the number of pollen beetles was the lowest on the plots fertilised with sulphur, magnesium, copper and boron, and the highest on the untreated plots on the plots fertilised with molybdenum. Our investigations suggest that adult pollen beetles seemed to be able to discriminate flowers fertilised with different nutrients.
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