Population dynamics of the West Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire): a simulation analysis

Abstract

The West Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire) is a major pest of the sweet potato Ipomoea batatas (L.) Lam. and this weevil is a target of an eradication program using the Sterile Insect Technique in Okinawa Prefecture, Japan. Understanding the population ecology is essential in the planning of an eradication program; hence, a host‐plant infestation survey and light trap survey have been conducted to monitor the population dynamics of the weevil on Kume Island (Okinawa Prefecture), which is the target area of the trial weevil eradication project. Seasonal tendencies of weevil density were found in these field surveys, but the tendency found in the host‐plant infestation survey was not seen every year, and the effectiveness of the light trap is somewhat suspect. To confirm the reliability of the tendency observed in these field surveys, the present study attempted to explain the tendency by a seasonal temperature change using a temperature‐based model of weevil population dynamics. The seasonal changes of weevil density differed according to host plants and host‐plant fields. The seasonal changes of weevil density inside the host plant Ipomoea indica and outside the host plants in I. indica fields were consistent with those predicted by the model. However, those inside the host plant Ipomoea pes‐caprae in the host‐plant infestation survey were contrary to the predicted ones, and those observed outside host plants in I. pes‐caprae fields by the light trap survey were not in good agreement with the predicted ones. It was concluded that the seasonal change of the weevil density observed in I. indica and I. indica fields can be explained by a seasonal temperature change, but factors other than seasonal temperature change are needed to explain those in I. pes‐caprae and I. pes‐caprae fields.

Invertebrate pests and diseases of sweetpotato (Ipomoea batatas): a review and identification of research priorities for smallholder production

“…In Okinawa Prefecture, Japan, an eradication program for E. postfasciatus has been running since 1994 (Moyer & Miyatake, 2001;Kumano et al, 2008;Sato et al, 2010). The release of sterile males aims to reduce populations which, along with other techniques, aims to make this prefecture free of this pest.…”

“…The life cycle of E. postfasciatus, is similar to that of C. formicarius, although it has not been reported to fly (Sherman & Tamashiro, 1954;Raman & Alleyne, 1991). Extensive research on the biology and ecology of E. postfasciatus was conducted as part of the Japanese eradication program (Moyer & Miyatake, 2001;Kumano et al, 2008;Sato et al, 2010).…”

“…The release of sterile males aims to reduce populations which, along with other techniques, aims to make this prefecture free of this pest. This eradication programme is expected to take a long time due to the long generation time and problems that have occurring during the mass rearing (Sato et al, 2010). The general utility of this approach is limited by the fact that weevils, even C. formicarius which is capable of flight, mostly move by crawling (Reddy et al, 2012b(Reddy et al, , 2014a.…”

The Major Sweet Potato Weevils; Management and Control: A Review

“…Rough weevil, striped weevils, and peloropus weevils are other weevil pests of sweet potato [16,31,32]. The different Cylas spp are located in distinct geographic regions, but their mode of action and damage symptoms to sweet potato plant are similar (Table 1) [ [33][34][35][36][37][38][39][40][41][42][43][44][45].…”

“…Adult stage Feeding in groups, fully into the storage root, causing extensive and numerous holes, and slight punctures above the whole surface [22]. Ecology and biology of Euscepes postfasciatus research were examined as part of the destruction work by the Japanese [39,44,45].…”