Potential of Ethiopian mustard, Brassica carinata as a trap crop for large white butterfly, Pieris brassicae infesting Indian mustard, Brassica juncea

Abstract

The large white butterfly, Pieris brassicae (L.), is an important pest of Indian mustard, Brassica juncea (L.) Czern., and inflicts heavy damage to all the above ground plant parts with strong yield reducing impacts. Farmers have few practical options other than to spray insecticides to protect their crop. In this study, an attempt was made during 2012–2013 and 2013–2014 crop seasons at Ludhiana, India, to evaluate Ethiopian mustard, Brassica carinata A. Braun as a trap crop to manage this pest as an alternate pest management strategy. B. carinata borders surrounding B. juncea were compared to chemically protected B. juncea and control (without B. carinata borders) plots for their effects on P. brassicae infestation and grain yield. Oviposition preference of adult butterflies was studied in a two-choice test in field cages, while the effect of two host plants on larval performance was studied under laboratory conditions under no choice conditions. B. juncea plots bordered with B. carinata harbored significantly lower larval population compared to control B. juncea plots during both the seasons. The grain yield in the bordered plots was also significantly higher than that from control plots and was statistically non-significant from that obtained in chemically protected plots. Female butterflies showed distinct oviposition preference for B. carinata over B. juncea and the larvae reared on B. carinata completed development in shorter period and grew bigger and heavier than those reared on B. juncea. Results indicated that B. carinata has potential to be used as trap crop to manage P. brassicae.