AB Umaru, M.C. Dike, I Onu and MN Ukwungwu
Experiments were conducted at Edozhigi in the Southern Guinea Savanna zone of Nigeria between 2004 – 2007 on the use of P. scrobiculatum to enhance the biological control mechanism of Africa gall midge (AfRGM) by two naturally occurring parasitoids in six rice varieties. Both P. scrobiculatum as a lowland rice weed and rice as a crop have the same parasitoids range. The six varieties were FARO 51, FARO 52, FARO 37, TOS 14519, BW 348 – 1 and a local variety all having varying levels of tolerance to AfRGM. These varieties as treatments were laid out in a randomized complete block design with three replicates and each was surrounded with one – metre band of P. scrobiculatum except the local variety as control. All the varieties were scored for gall midge infestation at 42 DAT and 63 DAT (days after transplanting) and all the galls were dissected to assess the presence of parasitoids. Results indicated that the presence of galls of P. scrobiculatum had moderating influence on the incidence of gall midge signifying that P. scrobiculatum galls were able to attract parasitoids to lower the AfRGM infestation. A fact of particular importance is that FARO 37 which is a known highly susceptible rice variety consistently maintained low levels of AfRGM.
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