Habitat Management Influence of Orseolia oryzivora and its Parasitoids on Rice

Abstract

The study investigated the application of eco-engineering approach for rice yellow mottle disease management caused by Rice yellow mottle virus in rain-fed lowland rice fields at Edozhigi and Makurdi, Nigeria between 2012 and 2015 cropping seasons. The experiment was laid out in Randomized Complete Block Design (RCBD) with fourteen rice genotypes obtained from AfricaRiceCenter, Cotonou and National Cereals Research Institute, Badeggi. The Lady's finger (Abelmoschus esculentum L.) was introduced on bounds to effect ecological modification in 2013 and 2015, whereas the conventional cropping system for rice without cultural modification was adopted for reference in 2012. The results indicated that RYMV incidence at 32 and 60 days after transplanting (DAT) was the highest in 2012 with the susceptible checks (FKR 28 and Sahelika) recording higher values in the range of 43.54 -48.03% across the two locations. Other rice yellow mottle disease indices such as plant height reduction (cm) and spikelets sterility (%) were also highest among the susceptible checks in 2012 when conventional cropping system was adopted across the two locations. The average mean yield of 2.26 t/ha obtained in 2012 was signifacnlty (P = 0.01) lower than respective mean yields (t/ha) of 3.01 and 3.09 obtained in 2013 and 2015 when the eco-engineering approach was adopted. The introduction of nectar-rich lady finger on rice bunds contributed to ecological modification which was apparent in wider range of insect presence in the field, and reduction of RYMV incidence by 50% at both locations. The present work has established for the first time in Nigeria the use of eco-engineering approach of planting nectar-rich plants to effect habitant manipulation and reduce spread and incidence of RYMV in natural field condition. The practice is therefore been recommended as a short/medium-term management approach for RYMV in disease endemic field locations.