Sweet Potato Resistance to <I>Euscepes postfasciatus</I> (Coleoptera: Curculionidae): Larval Performance Adversely Effected by Adult's Preference to Tuber for Food and Oviposition

Abstract

The preferences of the West Indian sweet potato weevil, Euscepes postfasciatus (Fairmaire), to tubers of sweet potato, Ipomoea batatas (L.), for food and for oviposition were evaluated, and correlated to sweet potato's resistance to immatures. Adults (parent) were released in a plastic box containing tubers of sweet potato cultivars and maintained for 5 d, after which the adults on each tuber were counted. All adults were then removed and each tuber was maintained separately. New adults that emerged from the tubers were counted. Cultivars were grouped by cluster analyses using the number of parent adults on the tubers and the number of new adults emerging from the tubers, adjusted for the weight of each tuber. Cultivars were divided into five groups: average level of preference, preferred, preferred for oviposition but not for food, preferred for food but not for oviposition, and not preferred. New adults from the first two groups took less time to eclose than those from the other groups, and their body size was smaller. In a second experiment, one to five cultivars were selected from each group and inoculated each tuber with 10 weevil eggs on each cultivar. Although the proportion of eclosed adults was not significantly different between cultivars, the time to eclosion was shorter and body size was smaller on preferred cultivars. The selection of tubers by parent adults was not linearly related with larval development, and did not reduce the survival of the immatures.

Review of major sweetpotato pests in Japan, with information on resistance breeding programs

“…Even if adults prefer a given cultivar for food and oviposition, the pest cannot increase rapidly unless the quality of the storage root also provides for larval development. Sweetpotato resistance to weevils has been reported in the laboratory and field (e.g., Blank et al 2001 , Bottega et al 2010 , França and Ritschel 2002 , Okada et al 2014 , 2015 , Silva and Ritschel 2001 , Wanderley et al 2004 ). However, few studies have considered the preference of weevil adults for certain cultivars and the suitability of the preferred cultivars for the juvenile development.…”

Feeding Behavior of Sweet Potato Weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae) on Three Sweet Potato, Ipomoea batatas L. Cultivars Grown in Tarlac, Philippines

“…Different subspecies of the pest occur in different areas of the world; however, their mode of infestation is almost the same (Capinera 2001). As cited by Okada et al (2014), the weevils have distinct modes of damage such that physical injury is inflicted when the weevils feed, therefore creating problems on the surface and flesh. Liao et al (2020) reported that tuber infestation of sweet potato weevils results in the induced production of secondary metabolites that eventually reduce tuber quality and marketability.…”

Preference of red mite Tetranychus ludeni Zacher (Acari: Tetranychidae) to sweet potato genotypes

“…Sweet potato genotypes show resistance to pests like Diabrotica spp. (Jackson and Bohac, 2007), Chaetocnema confinis Crotch (Abney and Kennedy, 2011) (Coleoptera: Chrysomelidae), and the root borer, Euscepes postfasciatus (Coleoptera: Curculionidae) (Okada et al, 2014).…”