Investigations on the interactions between Chrysoperla carnea (Stephens) (Neuroptera:Chrysopidae) and cotton aphid aphis gossypii glov. (Homoptera:Aphididae)

INVESTIGATIONS ON THE INTERACTIONS BETWEEN CHRYSOPERLA CARNEA (STEPHENS) (NEUROPTERArCHRYSOPIDAE) AND COTTON APHID APHIS GOSSYPII GLOV. (HOMOPTERArAPHIDIDAE) SUMMARY In this study, the interactions between Chrysoperla carnea (Stephens) (Neuroptera;Chrysopidae) and cotton aphid, Aphis gossypi i Glov. (Homoptera;Aphididae) are investigated. The functional response of C^. carnea larvae was studied with 5, 10, 20, 30, 40, 50 and 60 aphids per unit area at 25±1°C. Each experiment was replicated 5 times. The investigations were carried out in growth cambers with controlled temperature and photoperiod. The number of prey consumed by 1st. instar larvae of C\_ carnea increased up to level of 40 individuals per unit area but decreased in higher densities. Prey consumption of 2nd. and 3rd. instars increased as the prey density increased. The prey consuming capacity studies were carried out at 25±l°C and 30±1°C with 10 replicates. The cotton aphid consumption capacity of Ç_;_ carnea larvae increased as the instars aged. The 3rd. instar consumed the highest number of cotton aphids. The number of prey consumed per individual in each larval stage and during the whole larval period totaly at 25±l°C and 30±1°C respectively were as follows: for 1st. instar 53.6, 60.3; 2nd. instar 174.4, 88.6; 3rd. instar 724.4, 506.7 and totaly 952.4, 655.6 aphids. The developmental periods of each Ç^ carnea larval stage at 25±l°C and 30±1°C were as follows: for. 1. instar 3.07, 3.0 ;2. instar 3.07, 2.0; 3. instar 4.21, 3.09 and totall larval development period 10.35, 8.09 days respectively. The IXdevelopmental threshold of larvae was 7.1°C and thermal constant was 185.3 degree-days. Survival times of C^ carnea larvae in the absence of prey were as follows l. instar 3.6, 1.7; 2. instar 3.7, 2.5; 3. instar 6.2, 4.4, and in adult 3.7, 2.6 days at 25±1°C and 30±l°C respectively. The sex ratio of Ç_î, carnea was about 1:1 at both 25±l°C and 30±1°C.