Table 1. Evaluation of the assay system 1: dsRNA length-dependent competition.

1st RNAi	2nd RNAi		Initial # of larvae	# survived	# of 2nd instar	Lac2	WT	Suppression
1000 bp KA (10 ug/mL)	500 bp Lac2 (10 ug/mL)	co-feeding	20	15	15	7	8	53%
750 bp KA (10 ug/mL)	500 bp Lac2 (10 ug/mL)	co-feeding	19	16	13	8	5	38%
500 bp KA (10 ug/mL)	500 bp Lac2 (10 ug/mL)	co-feeding	18	17	10	6	4	40%
250 bp KA (10 ug/mL)	500 bp Lac2 (10 ug/mL)	co-feeding	16	15	11	7	4	36%

The length of the dsRNA used in the initial RNAi affects the efficiency of the subsequent second RNAi. Various lengths of KA dsRNA were used for the initial RNAi (1st RNAi), while 500 bp lac2 dsRNA was used for the second “marker gene” RNAi (2nd RNAi). The initial number of the larvae, the number of the larvae that survived the assay, and the number of larvae that became the second instar are indicated in the table. The second instar larvae were analyzed for their phenotypes, and categorized into the Lac2 phenotype (i.e. the second RNAi worked) and the WT phenotype (i.e. the second RNAi was suppressed). The suppression of the second RNAi phenotype by the initial RNAi was evaluated as the proportion of the WT larvae in the survived second instar larvae (Suppression).