Resistance of Bt-maize (MON810) against the stem borers Busseola fusca (Fuller) and Chilo partellus (Swinhoe) and its yield performance in Kenya

Tadele Tefera,Stephen Mugo,Murenga Mwimali,Bruce Anani,Regina Tende,Yoseph Beyene,Simon Gichuki,Sylvester O Oikeh,Francis Nang'Ayo,James Okeno,Evans Njeru,Kiru Pillay,Barbara Meisel,B.M Prasanna

doi:10.1016/j.cropro.2016.07.023

Abstract

A study was conducted to assess the performance of maize hybrids with Bt event MON810 (Bt-hybrids) against the maize stem borer Busseola fusca (Fuller) in a biosafety greenhouse (BGH) and against the spotted stem borer Chilo partellus (Swinhoe) under confined field trials (CFT) in Kenya for three seasons during 2013–2014. The study comprised 14 non-commercialized hybrids (seven pairs of near-isogenic Bt and non-Bt hybrids) and four non-Bt commercial hybrids. Each plant was artificially infested twice with 10 first instar larvae. In CFT, plants were infested with C. partellus 14 and 24 days after planting; in BGH, plants were infested with B. fusca 21 and 31 days after planting. In CFT, the seven Bt hybrids significantly differed from their non-Bt counterparts for leaf damage, number of exit holes, percent tunnel length, and grain yield. When averaged over three seasons, Bt-hybrids gave the highest grain yield (9.7 t ha−1), followed by non-Bt hybrids (6.9 t ha−1) and commercial checks (6 t ha−1). Bt-hybrids had the least number of exit holes and percent tunnel length in all the seasons as compared to the non-Bt hybrids and commercial checks. In BGH trials, Bt-hybrids consistently suffered less leaf damage than their non-Bt near isolines. The study demonstrated that MON810 was effective in controlling B. fusca and C. partellus. Bt-maize, therefore, has great potential to reduce the risk of maize grain losses in Africa due to stem borers, and will enable the smallholder farmers to produce high-quality grain with increased yield, reduced insecticide inputs, and improved food security.

Highlights

Maize is currently cultivated in about 25 million ha in subSaharan Africa, largely in smallholder systems that produce 38 million metric tons, primarily for food
The present study demonstrated the efficacy of MON810 in controlling the two major species of stem borers in Kenya, B. fusca and C. partellus
Bt maize was initially developed for the control of two stem borers in North America, namely Ostrinia nubilalis (Hubner) (Lepidoptera: Crambidae) (Ostlie et al, 1997) and Diatraea grandiosella (Dyar) (Lepidoptera: Crambidae) (Archer et al, 2001) before it was introduced for control of B. fusca (Fuller) (Lepidoptera: Noctuidae) and C. partellus (Swinhoe) (Lepidoptera: Crambidae) in South Africa (Gouse et al, 2005)

Summary

Introduction

Maize is currently cultivated in about 25 million ha in subSaharan Africa, largely in smallholder systems that produce 38 million metric tons, primarily for food. It is ideally suited for integrated pest management (IPM) strategies (Nester et al, 2002) In spite of these advantages, Bt based formulations have several disadvantages, as they need to be applied repeatedly and are effective only against immature stages of target insects feeding on exposed plant surfaces (McGaughey and Whalon, 1992). Growers are interested in Bt-crops because of the reduced need for application of broad-spectrum insecticides (Carpenter et al, 2002), increased or protected yields due to season-long control of the target insect pest (Rice and Pilcher, 1998), and improved grain quality as a result of lower mycotoxin levels due to reduction in fungal pathogens associated with insects feeding on the maize (Munkvold et al, 1999). This study, reports on the efficacy of maize with event MON810 against the two major stem borers of maize, B. fusca and C. partellus in biosafety greenhouse and confined field trials, respectively, in Kenya

Germplasm

Statistical analysis

Results

Discussion