Effects of Foliar-Applied Salicylic Acid, Flax and Caraway Oils on Caterpillar Biometrics on Lima Beans

Document Type : Original Article

Authors

1 Central Agric. Pesticide Laboratory, Agric. Res. Center, Plant Protection Research Station, Bacous, Alexandria, Egypt.

2 Pesticide Chemistry Dept., Fac. of Agric., Alexandria University, El-Shatby, Alexandria, Egypt

Abstract

The effects of salicylic acid, flax and caraway oils in either enhancing or inhibiting the lima bean plant’s defense against the feeding activity of cotton leafworm Spodoptera littoralis were tested. Treatments of salicylic acid as sodium salicylate (NaSA), flax and caraway oils were exogenously applied to lima bean seedlings. Antifeeding activity using cotton leafworm larvae for 48 hrs exposure as well as long-term effect of 12 days exposure were recorded. Plants treated with NaSA had encouraged the feeding ability by Spodoptera larvae that showed larger mass after 12 days of feeding with about 49.5% increase in larval growth rate. Flax oil with linolenic acid as the main component and the precursor of jasmonic acid (JA) increased the resistance of the host plants leading to an increased insect antifeeding activity and lower caterpillar growth rate by 39%. Treatment of caraway oil (23.5% carvone, 31.8% limonene) decreased the eating ability of the plant by caterpillars and hence inhibited larval growth rate by about 45% as well as increased average days to pupation with about 1.7 day. The present results indicate the importance of using elicitors of plant resistance in pest control programs that lead to activation of self induced resistance in treated plants. Flax oil and caraway oil have reasonable effects as potential inducers of lima bean plant resistance against cotton leafworm larvae.

Keywords