Field response of sugarcane cultivars to sugarcane soldier fly, Inopus rubriceps (Macquart) (Diptera: Stratiomyidae).

Abstract Ten commercial sugarcane cultivars were planted in 10 replicate plots in each of three field trials in southern Queensland, to evaluate their response to the sugarcane soldier fly Inopus rubriceps . Trials were monitored for three harvests. Numbers of soldier fly larvae differed slightly between cultivars, but probably not enough to prevent the development of damaging populations. Weights of larvae were the same on all cultivars, suggesting that antibiosis was not involved. The effect of soldier fly on performance of cultivars in each trial was examined by regression of number of ratoon shoots and subsequent number and weight of mature stalks and crop yield on larval density during summer-autumn within each crop class. Where statistically significant relationships were detected in ratoons, each increase in soldier fly density of 100 m-2 was associated with a yield reduction of 1.2-6.4 tonnes cane ha-1 , or 3-8% of the expected yield of uninfested plants. In most analyses, the slopes of regressions were the same for all cultivars, indicating no differential response to soldier fly infestation among the cultivars tested. [ABSTRACT FROM AUTHOR]