Bt ‐maize as a potential trap crop for management of Eldana saccharina Walker (Lep., Pyralidae) in sugarcane

  Notwithstanding the introduction of several pest management tactics, the stalk borer Eldana saccharina Walker (Lep., Pyralidae) remains the most serious pest in South African sugarcane. A novel tactic for managing this pest in sugarcane would be the use of a dead‐end trap crop that attracts moths for oviposition and curtails subsequent larval development, thereby reducing pest population size. Glasshouse bioassays, in which moths chose to oviposit on maize producing Bacillus thuringiensis Cry1Ab toxin ( Bt ‐maize), non‐ Bt ‐maize or sugarcane of two cultivars (borer‐resistant and ‐susceptible), showed that E. saccharina laid significantly more eggs and egg batches per dry leaf and unit mass of dry leaf on maize ( Bt or non‐ Bt ) than on either of the cane cultivars. When moths had a choice of ovipositing on 2‐, 3‐, 4‐ or 5‐month‐old maize ( Bt and non‐ Bt ), dry leaf number and mass of dry leaf material was significantly correlated with number of eggs and egg batches, indicating that older plants, which carried larger amounts of dry leaf matter, were more attractive for oviposition. Finally, glasshouse assays in which hatching larvae fed on 2.5‐, 3.5‐ and 4.5‐month‐old Bt and non‐ Bt ‐maize plants, showed that the Cry1Ab toxin was effective in killing E. saccharina larvae in all Bt ‐maize plant growth stages, confirming that Bt ‐maize fulfilled the third requirement (curtailing larval development) of a dead‐end trap crop for this pest. We argue that Bt ‐maize warrants further testing in the field as a trap crop, both alone and as a component of a ‘push–pull’ or habitat management system for E. saccharina in sugarcane.