The third instar larvae of
The basic feed was fermented oak sawdust that was mixed with 60% of oak sawdust, 30% of wheat bran, and 10% of previous fermented oak sawdust to provide useful microbes that help fermentation. To test the effects of feed additives, we added rice chaff and/or soybean cake based on the Table 1. The rice chaff and soybean cake were mixed with fermented oak sawdust. After mixing it, the feed were fermented for one more month.
Composition of four different feeds with two feed additives ？ rice chaff and soybean cake
The third instar larva was reared in a round petri dish (98 mm diameter X 15 mm depth) with enough designated feed. The rearing room was set as 25, 27.5 and 30℃ with ca. 40% humidity and 12:12(L:D) light condition. We measured body weight and state of each larva, and changed feed once per a week. For each treatment, 10 individuals for the third instar larvae were maintained for 14 wk. It was enough time for the most of second instar larvae to pupate. Three replications for each treatment were conducted. Each of three biological replications, independent batches of different feeds and temperatures, consisted of ten technical replications. A technical replication was a set of 12 different treatments ( four feeds X three temperatures). Averages and standard deviations of weight increase for each week, accumulated weight increase, and weight before pupation were calculated and compared each feed treatment to control feed with t-test and ANOVA analysis.
Larval weight gain was significantly different by rearing temperatures (d
[Fig. 1.] Means and standard errors of final larval weight after 14-week rearing on three different temperatures (25, 27.5, and 30℃). The means and standard errors were tested at 95% confidence level by Least Significant Difference (LSD) test.
Results for ANOVA test with three temperatures and four feeds. Ten P. brevitarsis larvae per each treatment with three replication were analyzed for their larval weight gain for 14 wk
As analyzing the effects of different feed additives, a feed with soybean cake and rice chaff showing the best effect on the larval weight gain (Fig. 2). However, the difference between the feed with soybean cake and rice chaff and the feed with soybean cake was not significantly different. However, the feed with rice chaff showed the least larval weight gain during 14-wk experiment. Even though the difference was not significant, adding rice chaff did not show meaningful effects on larval weight gain. The effects of different composition of feed on the larval weight gain of
[Fig. 2.] Means and standard errors of final larval weight after 14-wk rearing on four different feed compositions. The means and standard errors were tested at 95 % confidence level by Least Significant Difference (LSD) test.
When the interaction between rearing temperatures and different feed additives analyzed, the larval weight with control feed and feed with soybean cake was increased as the temperature increased from 25 to 30℃ (Fig. 3). In addition, the larval weight with soybean cake and rice chaff at 27.5℃ was lower than other two temperature condition, 25 and 30℃. Interestingly, the larval weight gain with rice chaff at 30℃ compared to 27.5℃. These results showed that the larval weight gain is different by temperature as well as the feed additives.
With four different feeds and three temperature conditions, we concluded that larvae reared with soybean cake at 30℃ showed the best result for the larval weight gain. However, the difference between the larval weight gain with soybean cake at 27.5 and at 30℃ was not significant, but it requires lots of resources to keep 30℃. Therefore, we concluded that it is the best to rear