Fungal and Bacterial Bioagents Efficiency on the Control of Potato Pest Phthorimaea operculella via Ingestion or Contact

Abstract

Potatoes are one of the most important food products in the world and considered a main human nutrition sources source. Potato tuber moth (Phthorimaea operculella Zeller (PTM) (Lepidoptera: Gelechiidae)) causes remarkable economic losses to important crop, both in field and under storage conditions In this study, the insecticidal efficiency of the following bioagents: Brevibacillus brevis (FD-1), Bacillus atrophaeus (FD 17), Bacillus sphaericus (FD 49), Bacillus cereus (FD 63), Vibrio hollisae (FD 70), Bacillus thuringiensis subsp. kenyae (FDP 8) bacteria strains and Beauveria bassiana fungal isolate (ET 10), were evaluated on their efficacy to control P. operculella, under controlled conditions. In addition to insecticidal efficacy evaluations, analyses were also carried out to determine the differences between bioagents action mode: (1) uptake (ingestion as a gastric poison) and (2) contact. For (1), 20 larvae were fed on the tubers immersed in these suspensions to analyze efficacy by ingestion; for (2), suspensions of 1x108 CFU/ml of bacteria and 5.7x105 conidia/ml of fungus were prepared and sprayed to 20 larvae. FD-63 (91.67%) and FD-17 (88.33%) taken up by diet gave the most effective results against the pest.