Feeding deterrence and inhibitory effects of bee balm (Monarda didyma) leaves on fall armyworm

Authors: Rabinowitz, Rebecca; Rowley, Amy; Brown, James; Meagher, Robert - Rob; RATHINASABAPATHI, BALA - University Of Florida

Submitted to: Proceedings Florida State Horticultural Science
Publication Type: Proceedings
Publication Acceptance Date: 3/14/2016
Publication Date: 4/1/2016
Citation: Rabinowitz, R.H., Rowley, A.L., Brown, J.T., Meagher Jr, R.L., Rathinasabapathi, B. 2016. Feeding deterrence and inhibitory effects of bee balm (Monarda didyma) leaves on fall armyworm. Proceedings Florida State Horticultural Science. 128:162-165.

Interpretive Summary: The fall armyworm is a serious pest of many field and vegetables crops in the U.S., Mexico, Caribbean, and South America. Although this insect feeds on a wide variety of crop plants, there are some plants that are considered “unattractive” to adult females laying eggs and to developing caterpillars. These plants could potentially be placed near crop plants so that both the border plants and crop plants are not attacked by fall armyworm. Researchers with the USDA, Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, along with University of Florida colleagues, tested bee balm and lemon balm as possible deterrent plants. In feeding studies, 94% of the caterpillars survived on corn, whereas only 1% and 48% of the caterpillars survived feeding on bee balm or lemon balm, respectively. Those caterpillars that survived on bee or lemon balm were much smaller and took longer to develop than those on corn. Therefore the results suggest that there is potential for the use of bee balm for fall armyworm control as a border plant. Research into the chemical composition of bee balm leaves may lead to future development as sprayable deterrent materials on crop plants.

Technical Abstract: The fall armyworm [Spodoptera frugiperda (J.E. Smith)] is a serious pest of many field and horticulture crops. Because of the many advantages for the use of plant-derived pesticides, we tested whether bee balm (Monarda didyma L.) leaves could have feeding deterrence on fall armyworm. When S. frugiperda larvae (neonates and instars 3–4) were supplied with freshly harvested leaves of Zea mays L. (corn), bee balm, or Melissa officinalis L. (lemon balm) for 9 days, 94% of the insects survived on corn leaves, yet, only 0.96% and 48% of the insects survived on bee balm and lemon balm leaves, respectively. For the larvae that survived, their growth on bee balm and lemon balm was significantly reduced (P < 0.001) compared to larvae fed corn leaves. When a choice between corn and bee balm leaves was given, the insect preferred corn leaves. The nature of the feeding deterrence was likely phytochemical rather than structural since fall armyworm larvae reared on an artificial diet mixed with macerated bee balm leaves were significantly (P < 0.05) inhibited when compared to those reared on an artificial diet mixed with macerated corn leaves. Our results suggest that there is potential for the use of bee balm for fall armyworm control.