Biology and biometry of sharpshooter Homalodisca coagulata (Homoptera : Cicadellidae) reared on cowpea
Stage-specific survival, growth, developmental biology, and biometry of the sharpshooter Homalodisca coagulata (Say) were studied in the laboratory under controlled conditions of 27 &PLUSMN; 1&DEG; C, 65 &PLUSMN; 5 RH, and a pbotoperiod of 14:10 (L:D) h. Nymphs and adults were individually reared on excised cowpea, Vigna ungiculata L. Walp., plants maintained in floral aquapics containing a hydroponic solution. Embryonic development of eggs was completed in 7.1 &PLUSMN; 0.8 d with 92.6% of the incubated eggs hatching. Nymphs molted five times, and the nymphal period of 61 &PLUSMN; 2.9 d for females was 1.2-fold significantly longer than that of males. The second nymphal stage was the shortest for both sexes (6.1 &PLUSMN; 0.5 d for females and 5.8 &PLUSMN; 0.8 d for males), whereas the last instar was the longest for females only. Stage-specific mortality was similar between instars; &AP; 36% of the nymphs molted to adults. H. coagulata adult sex ratio was not significantly different from a 1:1 ratio. Adult females lived 52 &PLUSMN; 11 d, and females deposited an average of 194 &PLUSMN; 35 eggs each. Analysis of life table statistics indicated that populations of H. coagulata increased at a rate of 1.045 per day and doubled within 15.6 d. The different H. coagulata growth stages were well described by body length, head capsule width, and hind tibia length; however, analysis of frequency distribution showed that bead capsule width was the most suitable parameter for distinguishing the immature developmental stages of H. coagulata.