Cold hardiness attributes of a field population of the potato tuberworm, Phthorimaea operculella

Abstract

The potato tuberworm, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae), is a worldwide pest of solanaceous crops especially devastating to potatoes. In the present study, we investigated the cold hardiness profile of acclimated and non-acclimated immature and adult stages of a field population of P. operculella. For both acclimated and non-acclimated individuals mean supercooling point (SCP) did not differ significantly among developmental stages. Unlike supercooling capacity, acclimation at 5°C for 5 days enhanced the ability to survive at subzero temperatures after a 2-h exposure. Median lethal temperature (LT 50 ) of all developmental stages (egg, late instar, pupa, and adult) decreased after acclimation, nevertheless only adults displayed a significant difference among acclimated and non-acclimated individuals concerning their LT 50 (À11.1 and À8.3°C, respectively). Generally, pupae were the most cold-tolerant developmental stage followed in decreasing order by the eggs and adults, whereas late instars were the least cold tolerant. Non-freezing injury above the SCP was well-documented for all developmental stages indicating a pre-freeze mortality and suggesting that P. operculella is considered to be chill tolerant rather than freeze intolerant. Nevertheless, given its high degree of cold hardiness relative to habitat temperatures, winter mortality of P. operculella due to low temperatures is not likely to occur and pest outbreaks may take place following a mild winter.

Cold tolerance characteristics of Korean population of potato tuber moth, Phthorimaea operculella (Zeller), (Lepidoptera: Gelechiidae)

“…The lowest supercooling point of eggs and early larvae may be due to their small sizes (Carillo & Cannon 2005;Hahn et al 2008;Zheng et al 2011;Hemmati et al 2014). However, in contrast to Iranian and Korean populations of PTM, Andreadis et al (2016) found the lowest SCP for adults and last instar field-collected larvae for the Greek population of PTM. They also found the early stage larvae have a lower SCP than later stages, because of the higher amount of glycerol and other small cryoprotectants.…”

“…It is well documented that the low temperature stimulates the production and accumulation of the cryoprotectant elements in the insect body (Storey & Storey 1996;Fuller 2004;Storey & Storey 2012;Cha & Lee 2016). Survival at subzero temperature of PTM was studied by Langford (1934), Hemmati et al (2014) and Andreadis et al (2016). Khani et al (2007) found that the elevated amount of trehalose in overwintering larvae is correlated with a very low supecooling point in December rather than in larvae collected in autumn.…”

“…Survival at subzero temperature of PTM was studied by Langford (1934), Hemmati et al (2014) and Andreadis et al (2016). However, based on the LT 50 value given by Andreadis et al (2016), it is the pupal stage that was most cold tolerant followed by the egg and adult stage and larvae being the least tolerant developmental stage. When exposed to 24 hours for the temperature of 2°F all the stages of PTM died except egg (Langford 1934).…”

“…The egg was reported to be the most and the adult the least cold tolerant stage of the invasive population of PTM in Korea (Choe & Park 1980). Cold tolerance study of the PTM has been carried out with different laboratory and field populations in a variety of geographical regions (Hemmati et al 2014;Andreadis et al 2016) involving all developmental stages to provide some information on the supercooling capacity and lower lethal temperature. Further cold tolerance studies can give some insight into potential adaptations of the insect and their distribution and range expansion under harsh weather condition of temperate regions.…”

Determining the number of instars in potato tuber moth Phthorimaea operculella (Zeller) using density‐based DBSCAN clustering

“…Recent studies have reported that these pests are causing severe damage to tomato and tobacco crops (Aryal & Jung, ; Vanevagancheva, Atanasova, & Dimitrov, ). PTMs have high reproductive potential and can, by parthenogenesis (Liu et al, ), become highly tolerant to a wide range of temperatures (Andreadis, Poulia, Noukari, Aslanidou, & Savopoulou‐Soultani, ; Sporleder, Kroschel, Quispe, & Lagnaoui, ) and resistant to pesticides (Doğramaci & Tingey, ; El‐kady, ), making them difficult to control. Accurate determination of the number of instars in pests is the basis for life table analyses, forecasting the outbreak of pest insects, key factor analyses and other aspects of integrated pest management programmes (Logan, Bentz, Vandygriff, & Turner, ).…”