D3134: Influence of host plant resistance on development and supercooling point of sweetpotato weevil, Cylas formicarius elegantulus (Summers)

Host plant resistance is an efficient, economical, and environment-friendly tool of pest management that enables a plant species or variety to resist pest attack by influencing the life-cycle parameters and fitness of the pest. The sweetpotato weevil (SPW), Cylas formicarius elegantulus (Summers) is the most destructive insect pest of sweetpotato production, causing damage both in field and storage. To combat SPW, the development of resistant sweetpotato lines has been seen as a priority for SPW- integrated pest management. Feeding by adult and larval SPW induces terpenes, rendering storage roots unmarketable. To reduce storage root damage and SPW populations, the present experiments tested the impact of sweetpotato varietal resistance on developmental time, adult emergence, body length, weight, and supercooling point of SPW. The varieties chosen were Beauregard and Evangeline, both susceptible to SPW, and Murasaki, a variety known to be resistant to SPW. There were no differences in developmental time. However, adult emergence from Beauregard (37.4 ± 3.6) and Evangeline (36.9 ± 2.3) was greater than Murasaki (5.2 ± 1.9). Although fewer in number, adults emerging from Murasaki were heavier and supercooling points (-17.9 ± 0.4°C) were lower than Beauregard (-16.3 ± 0.5°C) but similar to Evangeline (-17.1 ± 0.4°C). Host plant resistance expressed by Murasaki may significantly reduce SPW populations, but those that emerge may be better suited to survive the cold.