Foliar application of entomopathogenic nematodes and fungi for the management of the diamond back moth in greenhouse and field

Abstract

Diamondback moth, Plutella xyllostella Linnaeus (Lepidoptera: Plutellidae), is a pest affecting broccoli crops worldwide. In this study Heterorhabditis bacteriophora Poinar (Rhabditida: Heterorhabditidae), strain HNI0100, Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae), strain Bb9205, and Metarhizium anisopliae (Metchinikoff) Sorokin (Hypocreales: Clavicipitaceae), strain Ma9236, combined application was evaluated for P. xyllostella control under greenhouse and field conditions. Greenhouse assays were performed first spraying fungi at day 0 (0, 1 × 105, 1 × 106, and 1 × 107 conidia/cm2), followed by infective juvenile application after two, four, and six days at 0, 300, 600 and 1200 IJs/cm2. Based on highest broccoli plant protection under greenhouse conditions a combination of M. anisopliae Ma9236 (1 × 105 conidia/cm2) and H. bacteriophora HNI0100 (1200 IJs/cm2) was selected for field assays sprayig three applications of IJs two and four days after fungus application during the crop’s productive cycle. Data evidenced treatments with two applications produced the least damage percentage and resulted in highest productivity. Progressive damage percentage of broccoli leaves stopped when the second application took place. In regard to broccoli crop productivity, represented by broccoli’s head weight, combined application treatments of biocontrol agents presented higher values, regardless of the number of applications. Therefore, according to evaluated field conditions, to reduce damage and increase productivity, it is recommended to perform two applications with controlling agents during the vegetative stage and head formation. These results confirm combined use of fungi and entomopathogenic nematodes is an efficient alternative to control diamondback moth.