Cold tolerance of the sweet potato weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae), from the Southwestern Islands of Japan

Abstract

The cold tolerance of Cylas formicarius from five islands in the southwest of Japan was studied. The thermal threshold of the reproductive activity of adults tended to be lower and the supercooling point of the pupae was a little higher for the Okinawa-Honto population than for the others. The cold tolerance of the adult weevils was slightly accelerated by cold acclimation to 15°C for 4 d. Reproductive diapause induced under 10L : 14D increased cold tolerance significantly. Therefore, the cold tolerance of adult weevils would be accelerated by both cold acclimation at decreasing temperatures from autumn to winter and reproductive diapause induced by short daytime hours. When considering the increased cold-tolerence of C. formicarius through such mechanisms together with the temperature conditions in winter at the northern edge of its distribution area in the USA, C. formicarius probably has the capability to survive in the coastal zone of the Pacific Ocean in southern and central Japan.

Life‐history changes in the cold tolerance of the two‐spot spider mite Tetranychus urticae: applications in pest control and establishment risk assessment

“…, especially because there is some evidence that 5 °C may enhance the long‐term survival of T. urticae (Khodayari et al ., ). Acclimatory responses are also identified in many other important pests, such as the sweet potato weevil Cylas formicarius and the melon thrip Thrips palmi (McDonald et al ., ; Kandori et al ., ), as well as the generalist predator Euseius gallicus (N. White, S. A. L. Hayward & J. S. Bale, unpublished data). With an LTime 50 of 40.5 days for acclimated E. gallicus adults, the maximal field survival is predicted to be 80 days; however, the survival is reported to only reach 50% mortality after 116 days in the field.…”

“…Cold acclimation (the exposure of individuals to sublethal temperatures) and diapause are also shown to influence low temperature tolerance in many arthropod species (Denlinger, 1991;Morewood, 1993;Kandori et al, 2006;Takano, 2014) and there is good evidence for similar molecular processes underpinning both these processes (Ding et al, 2003;Hahn & Denlinger, 2011;Khodayari et al, 2013;Teets & Denlinger, 2013). Adult female diapause is assumed to be the only overwintering stage of T. urticae from a wild population in Iran, as shown by their significantly increased cold hardiness in the diapause state.…”

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].…”

“…It causes damage to the majority of pre-harvest sweet potato plant [34,35]. The insect can tolerate low temperature, especially during the winter to some extent, even it is a tropical and subtropical insect [36]. Weevils attack sweet potato crop at a higher altitude of 1600 m about sea level [37].…”

Evaluation of ten botanical insecticides against the sweet potato Weevil, Cylas formicarius (Fabricius, 1798) (Coleoptera: Brentidae)

“…The sweet potato weevil, Cylas formicarius (Fabricius) (Coleoptera: Brentidae), is an important insect pest of the sweet potato, Ipomoea batatas (L.) Poir.. C. formicarius attacks sweet potatoes both in the field and during storage, thus causing significant damage and yield losses between 3 and 80% (Kandori et al, 2006). Adult C. formicarius damage the vines, crowns, petioles, and storage roots of sweet potatoes, and the females lay their eggs under the epidermis of older portions of vines and storage roots.…”