Greenhouse and Field Evaluation of a New Male Annihilation Technique (MAT) Product, SPLAT-MAT Spinosad ME™, for the Control of Oriental Fruit Flies (Diptera: Tephritidae) in Taiwan

Abstract

The attraction and toxicity of a novel male annihilation technique (MAT) product, SPLAT-MAT Spinosad ME™ (SPLAT-Spin-ME), to the male of the oriental fruit fly (Bactrocera dorsalis) was evaluated under both greenhouse and field conditions in Taiwan. SPLAT-Spin-ME is a viscous, MAT formulation containing low doses of spinosad (2%) mixed with the powerful male-specific parapheromone attractant methyl eugenol (ME). The proprietary carrier formulation, SPLAT ® , provides a metered release of the toxicant and the attractant into the environment. In greenhouse cage trials the attraction rates of B. dorsalis males for the two MAT treatments (SPLAT-Spin-ME, naled+ME) were equally high at 0, 1, and 2 weeks weathering time-points, and uniformly low for the two bait spray treatments (GF-120 bait spray, malathion protein bait spray). The mortality of B. dorsalis males in greenhouse cage studies for the two MAT treatments was highest with SPLAT-Spin-ME outperforming naled+ME at the 1 and 2 weeks weathering periods both at the 24 h and 48 h grading intervals, with neither bait spray treatments providing a substantial mortality. The results from the field cage studies were the reverse of the results from the greenhouse evaluations. In the field cage studies naled+ME (8 mL) maintained a consistent ca 70-76% attraction rate of up to 7 weeks, whereas SPLAT-Spin-ME (1 g) demonstrated a relatively rapid decline in attraction from an initial 51% to 32% and below starting at week 4. Based on a 48 h grading period, naled+ME generated 92-100% mortality in the field mortality bioassay at all weathering time-points from 0-8 weeks, whereas SPLAT-SpinME provided 88-100% mortality, but only through week 3. The markedly better performance of naled+ME in the field vs. the greenhouse bioassays is