Effects of Temperature OnThe Development, Food Consumption and Utilization Parameters of the Last Two Larval Instars of Spodoptera littoralis (Boisd.)

Wedad E. Khafagi, Esmat M. Hegazi and Neama A. Aamer

 

Full Length Research Paper I Published July,2016

 

Journal of Agricultural Science and Food Technology  Vol. 2 (6), pp.93-99

 

 

ABSTRACT

 

Spodoptera littoralis (Boisd.) is one of the most destructive agricultural lepidopteran pests in Egypt. About 90 to 95% of total defoliation occurs during the last two larval instars. Sets of caterpillars were raised on artificial diet from hatching at one of four constant temperatures 15, 20, 25, or 30^ºC. The effect of temperature on the development and food utilization during the last two larval stages were examined. The duration of development of both penultimate and ultimate instars significantly decreased as the temperature increased from 15 to 30ºC. At each temperature, the duration of penultimate instar was significantly shorter than the ultimate ones. The development of both penultimate and ultimate instars of S. littoralis larvae was significantly fastest at 30ºC and slowest at 15ºC. The insect had an extra moult at 20 (23.7%) and 25ºC (8.5%) before pupation. The various rearing conditions affected the different nutritional values. The data of nutritional indices for the fifth and sixth instars of S.littoralis are not generally consistent with each other. Approximate digestibility (AD) values of the last two instars were highest at 25ºC and lowest at 30ºC.So, S.littoralis is better developed at 25°C, than any of the other rearing temperature.

Key Words: Spodoptera littoralis, Constant temperature, larval critical weight, Instar number, growth and Nutritional parameters.
 

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