A Semi-Synthetic Diet and the Potential Important Chemicals for Mythimna separata (Lepidoptera: Noctuidae)

Abstract

Armyworm feeding in large, destructive groups is hugely difficult to control and the oriental armyworm, Mythimna separata (Walk), is one such pest. In this study, we reported a semisynthetic artificial diet for the oriental armyworm. This diet is based on Ritter’s diet, a formula developed for Heliothis zea. The survival of M. separata was extremely low and only around 2% insects can reach the adult stage on Ritter’s diet. But, it can reach up to 100% if corn leaf powder (CLP) was mixed, and insects grew faster and gained more mass. After testing a set of mixtures of Ritter’s diet and CLP, we found that 14.3% was the optimal proportion of CLP for making the artificial diet. We then used chloroform to extract CLP. Insect performance was still much better on Ch-extracted CLP diets than that on Ritter’s diet, but it was poorer than that on the diets containing unprocessed CLP, suggesting that the essential factor(s) was only partially extracted from corn leaf. We then used methanol and dichloromethane, two solvents differing in their polarity, to process the extractions and analyzed the extracted chemicals using gas chromatography–mass spectrometry (GC-MS). Insects had a better performance on dichloromethane-extracted CLP diet in comparison to methanol-extracted one, indicating that the important factor(s) is more prone to methanol extraction. The reported recipe here is useful for the research on M. separata and possibly other grain-crop eating armyworms. The functions of the chemicals extracted from corn leaf tissue can be investigated in the future studies.

The Effects of Diet on the Immune Responses of the Oriental Armyworm Mythimna separata

“…Artificial diets were prepared following the previous method [ 40 ]. The P:C ratios were made by altering the amounts of protein source (Casein, Albumin, and Peptone) and carbohydrate source (sucrose) in the diet.…”

Optimization of the application of the CRISPR/Cas9 system in Mythimna separata

“…Eggs produced by these adults were allowed to hatch. All larvae were individually reared on an artificial diet in 24‐well cell culture plates, and kept in an incubator set at 28 ± 1 °C, 75 ± 5% r.h., and L16:D8 photoperiod (Jia et al, 2019). According to preliminary observations, M. separata mated and reproduced during the dark period.…”

“…All eggs were incubated in Petri dishes containing 3% agar gel. Upon hatching, the newly emerged larvae were counted, individually reared on an artificial diet, and checked daily (Jia et al, 2019). The dead larvae were stored in ethanol.…”

Discrepancy in Sterol Usage between Two Polyphagous Caterpillars, Mythimna separata and Spodoptera frugiperda

“…All larvae were individually reared on an artificial diet in 24-well cell culture plates and kept in an incubator at 28 ± 1 °C, 75 ± 5% RH, with an L16:D8 photoperiod. Semi-synthetic diets were prepared according to the procedure described previously [ 35 ]. Food that slightly exceeded daily consumption was provided and refreshed daily.…”