Age-specific larval survival of Laguna and Isabela Asian corn borer populations on Bt and non-Bt corn
2016
Caasi-Lit, M.T. | Suyat, E.A.
The efficacy of corn hybrid MON89034 against Asian Corn Borer from Laguna and Isabela [Philippines] was determined using forced larval transfer technique desired specific instars. Possible resistance and survival of the pupal stage of specific larval instars on this double Bt line that expresses both Cry2Ab2 and Cry1A.105 proteins were studied. The experiment used leaf squares and stalks of 30 DAP whole plants of Bt and non-Bt varieties grown in staggered manner in the screenhouse. Larvae were reared and fed on NK603 until they were transferred to MON89034 upon reaching the different specific instars. Bt leaves and stalks were contained in Balla jars and Petri dishes with 30 replicates each. Mortality and damage ratings were recorded daily. Based on the initial results, older larvae infested onto Bt corn leaves on stalks survived longer than younger larvae. Furthermore, results showed that greater damage was caused by the older as compared to younger larvae as shown by the scrapes and shot holes on the leaves and bores on the stalks. Results may provide insights on the pattern of behavior of the insects for the succeeding generations. Possible reasons for the development of ACB resistance against Bt toxins may be explained through the study.
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