Abstract
Crude extract of Anabaena flos aqua alga cyanobacterial strains was evaluated in laboratory as a biocomponents against 2nd and 4th instars of the cotton leaf worm, Spodoptera littoralis (Boisd.). Larvae were treated with the algal extract via contact and feeding methods. Effect of the algal extract varied according to the larval instars and the method of application. Contact algal treatment was more effective than the feeding treatment. The 2nd larval instar was more susceptible than the 4th one. LC50 value for the 2nd larval instar of S. littoralis was 12.5 ppm compared with 25 ppm for the 4th instar. In case of feeding treatment, they were 50 and 100 ppm for the 2nd and 4th instars, respectively. LC50 value of the contact method induced highly significant increase of the larval and pupal durations, adults' emergence decrease to 59.5%, compared with 99.7% for the untreated control. It induced the highest percentage of pupation (43%) and adults' malformation reached 25%. Adults emerged from the treated 4th larval instar recorded high reduction in numbers of deposited egg (reached 28.3 eggs/ female) compared with (475 eggs/ female) for the control. Eggs fertility was decreased to 78.4% compared with 100% for the control. Highly significant reduction in the percentage of pupation was observed. Also, LC50 values obtained from the contact or feeding treatments on the 4th larval instar reduced the longevity of the resulted adults and percentage of the adults' emergence. Disorder for the sex ratio was observed.