Influence of Cropping and Irrigation Systems on Population Fluctuation of the African White Rice Stem Borer (Maliarpha separatella Rag) and Damage on Rice

Abstract

Information on the population fluctuation of African white rice stem borer (Maliarpha separatella Ragonot), which is a major rice pest in Kenya, is not known. Availability of such information can assist in the development of an integrated management strategy for the pest. Therefore, a study was conducted at Mwea irrigation scheme in Central Kenya, to investigate the influence of irrigation water provision and cropping systems on population of M. separatella. Farmer fields in different parts of the scheme were sampled every fortnight. The farms represented three irrigation water provision schedules and three cropping systems regimes. The irrigation water provision schedules were, System of Rice Intensification (SRI), flood irrigated (conventional method) and sporadic irrigation. The cropping systems were main season crop (conventional method), double crop and ratoon. Water provision schedules were treated as main plots, while cropping systems were the sub plots. Results showed that the highest percentage of white heads (13.66) occurred in areas, where rice was double-cropped and where, there was sporadic water provision (9.70). There were no significant differences in the number of white heads (empty panicles) between the on-season (6.37) and ratoon (4.25) cropping system. There were also no differences between flood (4.42) and System for rice intensification (5.48) methods of irrigation. This study demonstrates that irrigation methods and cropping systems greatly influence fluctuation of M. separatella infestation and suggests that in case of double cropping it will be necessary to control the stem borer and efforts should be made to ensure that farmers synchronize planting dates.

Incidence and relative abundance of rice stem borers in three selected rice fields in Lagos and Ogun States, Nigeria

“…The populations of rice stemborers in Igbogun (mangrove swamp) and Itoikin (rainfed lowland) were observed to be higher than that of the rice field in Agbajege(upland), this is due to the favorable environmental conditions encouraging the proliferation of the rice stemborers in the lowland areas (Alams,1992;Kega et al, 2015). This agrees with Sarwar (2012) and Kega et al (2015) that reported a notable increase in stemborer activities under high humid conditions, while Alam et al (1984) and Ukwungwu (1984) also reported a similar trend of increased activities among rice stem borers in lowland rice fields in Nigeria.…”

“…The populations of rice stemborers in Igbogun (mangrove swamp) and Itoikin (rainfed lowland) were observed to be higher than that of the rice field in Agbajege(upland), this is due to the favorable environmental conditions encouraging the proliferation of the rice stemborers in the lowland areas (Alams,1992;Kega et al, 2015). This agrees with Sarwar (2012) and Kega et al (2015) that reported a notable increase in stemborer activities under high humid conditions, while Alam et al (1984) and Ukwungwu (1984) also reported a similar trend of increased activities among rice stem borers in lowland rice fields in Nigeria. Also, Luo et al (2021) reported that Chilo suppressalis survived under high water conditions as they tend to move away quickly when compared to Scirpophaga incertulas Walker, which further explains the ability of striped stemborer colonizing the late planted rice almost immediately after migrating from the early sown rice and over wintering sites.…”

“…In Africa, different studies have been explored to identify the species of rice stemborers across uplands and the lowland rice fields (Bonaventure et al, 2018;Alfonce and Gration, 2015;Kega et al, 2015). In Nigeria, the major rice stem borers belong to two orders: Diptera and Lepidoptera.…”