DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 7-8/2014 str. 36     <-- 36 -->        PDF

observed during April, and in the first decade of May they ceased. The first copulation in 2009 were observed in early April, and the last in early May probably due to the late occurrence of overwintered adults. Termination of copulation in early May might be explained by the fact that most of the overwintered females die after laying eggs. Although the number of adults on ash branches in both years increased from mid-May due to the occurrence of the adults of new generation the copulations were not observed.
By dissection and observation of female reproductive organs during winter diapause revealed that the eggs were not formed in the ovaries. By growing ash weevil females after activation and by observation of reproductive organs of three females every three days, it was determined that the process of oogenesis started immediately after beginning of additional feeding. Fully developed eggs in females were noticed 12 days after female activation (Table 1).
In females grown aimed at fertility and total fecundity determination, the beginning of egg laying was observed from 12 to 22 days after their activation. The oviposition period was quite long and in females grown in the trial for fertility determination it lasted up to 51 days. Over the course of one day the females layed from 1 to 14 eggs into one to four chambers previously made in buds, shoots and leaf petals. During egg laying the pauses ranging from 1 to 4 days were observed. From 1 to 8 eggs were oviposit into one chamber. From the total of 429 observed chambers one egg was oviposited in only 4.9%, two eggs in 19.6%, three in 35%, four in 22.1%, five in 12.1%, six in 3.5%, seven in 2.3%, and eight eggs were observed in only 0.5% of chambers. The mean number of eggs per chamber was 3.39. It was observed that females oviposit their eggs in the same bud for several times. Oviposition was confirmed in each of the 20 females grown in the trial. The number of the oviposited eggs depended on the female and ranged from 30 to 104, while the average number was approx. 67. Dissection of dead female revealed remaining eggs in the ovaries, and their number ranged from 2 to 28. Total fecundity of the females ranged between 58 and 109 eggs – on the average 76 eggs per female. It was confirmed that embryonic development ranged from 9 to 11 days (on average 9.6 days).
On 15 ash branches reviewed in 2008 the first larvae were observed on April 18th, and the last on June 13th (Figure 3).
The greatest number of larvae was observed at the end of the first decade of May. The occurrence of the first larvae in the following year was confirmed six days later in regard to 2008, and the last larvae at the end of June (Figure 4).