Overwintering biology and limits of cold tolerance in larvae of pistachio twig borer,Kermania pistaciella

Abstract

Pistachio twig borer, Kermania pistaciella is an important pest of pistachio trees. It has an univoltine life-cycle and its larvae tunnel and feed inside pistachio twigs for almost 10 months each year. The last larval instars overwinter inside the twigs. Survival/mortality associated with low temperatures during overwintering stage is currently unknown. We found that overwintering larvae of the Rafsanjan (Iran) population of K. pistaciella rely on maintaining a stably high supercooling capacity throughout the cold season. Their supercooling points (SCPs) ranged between -19.4 and -22.7°C from October to February. Larvae were able to survive 24 h exposures to -15°C anytime during the cold season. During December and January, larvae were undergoing quiescence type of dormancy caused probably by low ambient temperatures and/or changes in host tree physiology (tree dormancy). Larvae attain highest cold tolerance (high survival at -20°C) during dormancy, which offers them sufficient protection against geographically and ecologically relevant cold spells. High cold tolerance during dormancy was not associated with accumulation of any low-molecular mass cryoprotective substances. The SCP sets the limit of cold tolerance in pistachio twig borer, meaning that high mortality of overwintering populations can be expected only in the regions or years where or when the temperatures fall below the average larval SCP (i.e., below -20°C). Partial mortality can be expected also when temperatures repeatedly drop close to the SCP on a diurnal basis.

Overwintering Physiology and Cold Tolerance of the Sunn Pest, Eurygaster integriceps, an Emphasis on the Role of Cryoprotectants

“…During the overwintering stages, the cold tolerance of those insects, which are physiologically incapable of synthesizing and accumulating cryoprotectants, is usually accompanied by the SCP depression. That is to say, the SCP expansion is the main coldtolerance strategy deployed by this group of insects (Mollaei et al, 2016). However, in the insects with the capability of cryoprotectant biosynthesis and accumulation, the SCP changes are commonly limited, and the development of cold tolerance is commonly associated with cryoprotectant accumulation and/or SCP degradation (Zachariassen, 1985;Heydari and Izadi, 2014;Sinclair et al, 2015;Ditrich et al, 2018).…”

“…of the linden bug, P. apterus could strongly correlate with the ambient temperature; however, there was no direct relationship between the lowest ambient temperature and SCP. Mollaei et al (2016) also mentioned that the SCP values and the ambient temperatures did not follow the same direct seasonal trend in the overwintering larvae of Kermania pistaciella (Lep. : Tineidae).…”

“…However, the relationship between these two strategies is not clear. In some insects, these two are independent phenomena (Goto et al, 2001;Khanmohamadi et al, 2016;Mollaei et al, 2016;Mohammadzadeh et al, 2017), while in some other insects, cold hardiness is a component of the diapause syndrome (Milonas, 1999;Bemani et al, 2012;Heydari and Izadi, 2014;Cira et al, 2018). In most insects, development of cold hardiness is highly associated with some physiological adaptations, e.g., synthesis and accumulation of low-molecularweight carbohydrates and polyols (cryoprotection) (Behroozi et al, 2012;Vrba et al, 2017;Mohammadzadeh and Izadi, 2018a,b;Izadi et al, 2019), synthesis of antifreeze proteins or carbohydrates (Costanzo and Lee, 2013;Khanmohamadi et al, 2016;Mollaei et al, 2016), use of cryoprotective dehydration (Elnitsky et al, 2008;Clark et al, 2009;Worland et al, 2010), and regulation of ice nucleation (Costanzo and Lee, 2013).…”

Metabolic Response of Aphid Cinara tujafilina to Cold Stress

“…An increase in the level of proline during cold stress was also observed in Alphitobius diaperinus, Cryptolestes ferrugineus , and Sitophilus granarius [ 11 , 12 ]. An increase in proline, isoleucine, and valine was also observed in wintering Kermania pistacilla larvae, where the total amount of free amino acids was highest in November and then gradually decreased [ 37 ]. The increase in proline in the aphid body that we observed was probably due to its function as energy substrate and cryoprotectant, as in other overwintering insects [ 4 , 38 ].…”

Population fluctuations of the pistachio twig borer, Kermania pistaciella Amsel, 1964 (Lep.: Oinophylidae) using delta pheromone trap

“…Because the population of hibernating larvae of the pistachio twig borer depends on the continuity of extreme cold during the cold season (Mollaei et al, 2016), the appearance and the flight peak of the pest in different years depends on the different conditions of the region weather. Many experiments have been carried out in recent years to use the natural pheromone of K. pistaciella in pistachio orchards.…”