Plant defense elicitors as seed treatment against insects and implications for smallholder farmers.

Open Access
Author:
Paudel, Sulav
Graduate Program:
Entomology
Degree:
Master of Agriculture
Document Type:
Master Thesis
Date of Defense:
August 22, 2013
Committee Members:
  • Edwin George Rajotte, Thesis Advisor
  • Gary Felton, Thesis Advisor
  • Mary Ellen Barbercheck, Thesis Advisor
Keywords:
  • Plant defense elicitors
  • Methyl Jasmonate
  • Integrated pest management
Abstract:
ABSTRACT Seeds may be receptive to plant defense activators such as β-amino butyric acid (BABA) and jasmonic acid (JA), conferring protection to the subsequent plant against a wide spectrum of plant pathogens and insects. We examined the independent and interactive effects of methyl jasmonate (MeJA) seed treatment on tomato fruit worm (Helicoverpa zea) larval growth and the activity of the defensive protein, polyphenol oxidase (PPO), in leaves of tomato plants at three different plant stages. Additionally, we measured the dosage effects of MeJA seed treatment on several vegetative and reproductive traits. To assess the effectiveness against different insects, we tested MeJA seed treatment against the tomato leaf miner (Tuta absoluta) and tobacco caterpillar (Spodoptera litura), in Brazil and Bangladesh, respectively. Results suggest that seed treatment with defense elicitors will induce defenses in plants, which is correlated with increased PPO activity in leaves and reduction in larval growth. However, fitness costs in plants were observed with higher dosage of MeJA. The magnitude of the increase in chemical pesticide use in recent times in developing countries like Bangladesh is alarming, threatening to human health and the environment. We investigated level of pesticide use and status of non-chemical integrated management approaches presently among the small holder farmers, and interpreted the result to suggest how small integrated pest management (IPM) technology such as ‘seed treatment’ could be efficiently exploited in Bangladesh context. Key reforms recommended include screening of the technology under different conditions, making the seed treating elicitors easily available with proper label and formulation and government providing farmers with proper subsidies and training of know-how to encourage farmers who are interested toward non-chemical based pest management. If successfully integrated with other facets of an integrated pest management program, the use of MeJA as elicitors of plant defense could be an important tool in managing insect pests and contribute to a reduction in applications of chemical pesticides.