Growth threshold and heat units required for the growth and development of the predator Dicrodiplosis manihoti Harris Diptera: Cecidomyiidae when feeding on the citrus mealybug Planococcus citri (Risso) Hemiptera: Pseudococcidae

Abstract

This study was conducted in the laboratories and climate rooms of the Bio-control unit college of Agriculture / Baghdad University to study of effect constant tempreture on development time of predator and accumulated degree days of predator D.manihoti . The results also showed differences between the development  periods  of the predator D.manihoti   according to the rearing temperatures  being,   31.44 and 18.13 and 13.34 and 12.5 days at temperatures 20 , 25  , 30  and 35 ± 2 ° C, respectively .  the lowest developmental threshold of  egg , larval stage I, II and III and the pupal stage   as well as the duration from egg to  adult reached   8.98, 8.78, 8.63, 12.58, 8 ° and 9 C°  respectively, while    42.37, 28.24, 47.16, 43.85 and 139 heat unit, for the accumulated day degrees . The accumulated day degree of period from egg to adult was 303 heat units. Optimum temperature was   33.32 C° while Upper threshold was 42.39 Cₒ for   D.manihoti respectively.