Meridic diets for rearing of Spodoptera frugiperda larvae.
Two meridic diets, N4 and N6, containing pinto bean, wheat germ, soybean, whole milk and sucrose as main nutrients were developed for rearing Spodoptera frugiperda (Noctuidae) larvae. Six larval instars were observed when neonate larvae were individually raised on these diets in small petri-dishes (ø 50 × 10 mm, 19.6 cm3) at 25°C and 15:9 h (light:dark) photoperiod. The average pupation rate of 97.8% on the N4 diet was significantly higher than the rate of 85.6% on N6 diet. The emergence rates were 92.0% on N4 diet and 93.5% on N6 diet, with a non-significant difference. The larval periods were 17.9 and 17.7 days for females, and 18.7 and 18.5 days for males, for N4 and N6 diets, respectively, with non-significant differences between diets and sexes. The pupal periods on both diets were identical (11.1 days for females and 12.8 days for males), despite differences between sexes. The pupal weights of both sexes on N4 diet were identical with a value of 257 mg, whereas those on N6 diet were 256 and 263 mg for females and males, respectively, with a non-significant difference. The longevity of female adults that emerged on N6 diet was 13.8 days and longer than 8.6 days on N4 diet. The pre-oviposition periods were 5.0 and 4.2 days on the N4 and N6 diets, respectively, with a non-significant difference, however, the oviposition period of 6.5 days on N6 diet was longer than the period of 3.9 days on N4 diet. The effective fecundity on N6 diet was 1,392 eggs (maximum 1,776) and was higher than that of 942 eggs (maximum 1,694) on N4 diet, with a non-significant difference. The egg hatching rates on N4 and N6 diets were 79.2 and 79.8%, and egg periods were 3.0 and 2.9 days, respectively, with non-significant differences.