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Vol. 59, 2020
(update: 2020.05.22; 07.06)
Simultaneous Occurrence of
Diapause and Cold Hardiness in Overwintering Eggs of the Apple
Oystershell Scale, Lepidosaphes
Malicola Borchsenius (Hem.: Diaspididae)
Parvaneh
Nazari1, Nafiseh Poorjavad2, and Hamzeh Izadi3,*
doi:10.6620/ZS.2020.59-25
1Department
of Plant Protection, College of Agriculture, Isfahan University of
Technology, P.O. Box 8415683111, Isfahan, Iran. E-mail:
parvanehnazari@ymail.com (Nazari)
2Department of Plant Protection, College of
Agriculture, Isfahan University of Technology, P.O. Box 8415683111,
Isfahan, Iran. E-mail: npoorjavad@cc.iut.ac.ir (Poorjavad)
3Department of Plant Protection, Faculty of
Agriculture, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran.
*Correspondence: Tel: +98 34 3131 2012. Fax: +98 34 3131 2042. E-mail:
izadi@vru.ac.ir (Izadi)
(Received 27 March 2020 / Accepted 20
May 2020)
Communicated by Benny K.K. Chan
As
the key pest of apple fruits, the oystershell scale, Lepidosaphes malicola Borchsenius
(Hem.: Diaspididae), overwinters as diapausing eggs under the
protective, waxy cover of females. In this research, the effects of
diapause development, cold acclimation, and rapid cold hardening were
studied on the cold hardiness of the eggs. The changes in some
physiological components were also investigated. The results indicated
cold exposure to be a prerequisite for the survival of the diapausing
eggs of L. malicola. No eggs
hatched without exposure to cold. In addition, a direct relationship
was observed among cold hardiness, cold acclimation, and diapause of
the eggs based on the results. The highest level of hatching (the
highest cold hardiness) of the eggs (80%) occurred in the
cold-acclimated eggs at the end of diapause (March). Rapid cold
hardening also influenced the cold hardiness of the eggs with diapause
development. At the end of diapause, the lowest (61%) and the highest
(77%) rates of egg survival were observed when the eggs were exposed to
5 and -10°C for 24 h, respectively. Cold hardiness of the diapausing
eggs of L. malicola was also
accompanied by some physiological changes, i.e., a decrease in glycogen
content and an increase in simple sugar, lipid, and protein contents.
The lowest glycogen content (about 50 μg/g) and the highest amounts of
total simple sugars (454 μg/g) of lipids (542 μg/g) and proteins (84
μg/g) were observed in the cold-acclimated eggs at the end of diapause.
Key words: Cold hardiness, Cold
acclimation, Diapause, Apple.
Citation: Nazari P, Poorjavad N,
Izadi H. 2020. Simultaneous occurrence of diapause and cold hardiness
in overwintering eggs of the apple oystershell scale, Lepidosaphes Malicola Borchsenius (Hem.:
Diaspididae). Zool Stud 59:25.
doi:10.6620/ZS.2020.59-25.
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