Document Type : Original Article
Authors
1
Plant Protection Research Institute, Agriculture Research Center, Dokki, Giza
2
Dept.Sustainable Development, Environmental Studies and Research Institute, Sadat Univ., Egypt
Abstract
Earia insulana (Boisd.) (Lepidoptera: Noctuidae) larvae and/or pupae (cocoons) were collected from five different cotton varieties (Giza 45, Giza 86, Giza 87, Giza 88, and Giza 92) have been grown in Sakha, Kafr El-Sheikh-Governorate at the end of cotton season 2014. Some biological aspects of these populations were investigated under laboratory conditions at three constant temperatures (25, 27 and 30˚C).
The present results concluded that, the tested temperatures had main effect on stages durations, survival, adult emergence percentages, sex ratio, and fecundity of field SBW strain. Regardless the variety of cotton general trend of results indicated that, the highest, moderate and lowest percentage of emerged moths were recorded at 25ºC, 30ºC and 27ºC, respectively. In addition, sex ratio were almost 1:1 but tend to females at 25ºC while in reverse to male at 30ºC. At 27ºC sex ratio was 2♀: 1♂. Moreover, the fecundity of developed female from tested varieties recorded its highest values at 25ºC and sharply decreased at 27ºC. While, at 30ºC, the emerged female lost its fecundity except females of Giza 45 deposited 169.0 eggs / female. Furthermore, the tested temperature may be reliable for one developed stage of spiny bollworm and not reliable for another of same population. Also, cotton variety had highly significant effect on the studied biological aspects on its pest SBW, as well as, the interaction between cotton variety and temperature. Regardless temperature, duration of larval stage was 29 & 25.0 days on cotton varieties Giza 45 and Giza 87 at 25ºC, respectively. Although, the respective duration of generation in both cases acquire 50 days and 39.1 days, the reproductive capacity of SBW of Giza 45 equal ten times of that when fed on Giza 87. In addition, the larval mortality was higher in population of Giza 87. Depending on the aforementioned conclusion, cotton variety Giza 45 is more susceptible to SBW infestation. The authors arranged the susceptibility of tested cotton varieties to SBW infestation in descending order as follow: Giza 45, Giza 88, Giza 87, Giza 92 and Giza 86. These composite relations need to further vision to study the insect ecology, biology, physiology and economic damage. However, the use of less susceptible cultivars can be considered as a part of IPM control program.
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