Impact of three substances in different proportions on nymphal growth of Periplaneta americana.

Objective To identify the optimum feed formula for nymphs of Periplaneta americana.Methods The L9(34) design was employed to analyze the impact of wheat flour,milk powder and dry yeast powder of different proportions on the nymphal growth and development of P.americana.Results Experimental results showed that after 120 d of feeding,the body length increment(19.21 mm/nymph),daily food consumption(25.94 mg/nymph),weight(532.5 mg/nymph) and consumption rate(96.69%) of nymphs fed with formula S5 were higher than the values in those fed with other feed.Conclusion The optimum formula of feed for nymphs of P.americana was wheat flour:milk powder:dry yeast flour=2:4:1.Dry yeast powder was the key factor of nymphal body length increment for P.americana,which was conducive to the growth of nymphs.