# Host Adaptability and Genetic Mechanisms of the Rice Strain of Fall Armyworm (Spodoptera frugiperda)

## TL;DR

This study explores the genetic and biological reasons behind the rice strain of fall armyworm's ability to adapt to a wider range of host plants compared to the corn strain.

## Contribution

The study reveals the rice strain's broader host adaptability and dominant inheritance of this trait through hybridization.

## Key findings

- The rice strain shows stronger adaptability and detoxification on rice and ryegrass compared to the corn strain.
- Hybrid offspring display hybrid advantages, with host adaptability traits resembling the rice strain.
- The rice strain's host adaptability is dominantly inherited in hybrid offspring.

## Abstract

The fall armyworm is a major invasive pest that threatens global food security. It consists of two nearly identical biotypes—the rice strain (RS) and corn strain (CS)—which differ in host plant adaptation. Laboratory assays shows that the RS has a wider host range and stronger detoxification ability, especially on rice and ryegrass, compared to the CS. Although they can interbreed, hybridization outcomes are complex. Hybrid offspring display advantages in certain traits, with RS-like host adaptability being dominant. These results help clarify the genetic mechanisms behind RS’s broader adaptability.

The fall armyworm (Spodoptera frugiperda) is an invasive pest of global concern, posing a significant threat to food security. It can be divided into two biotypes: the rice strain (RS) and the corn strain (CS). These two biotypes are nearly indistinguishable morphologically but differ significantly in host adaptability. The two biotypes can hybridize, but the efficiency of their hybridization has not been conclusively determined. Our research has found that the two biotypes of fall armyworm exhibit significant differences in weight gain when feeding on different host plants and artificial diets. The rice strain has a broader diet range, showing notably stronger adaptability to rice and ryegrass compared to the corn strain, suggesting that the rice strain may possess more robust detoxification metabolism. Under laboratory conditions, the two biotypes can hybridize effectively, and their offspring exhibit certain hybrid advantages. The host adaptability traits of the rice strain are dominantly inherited. Our findings provide an important foundation for understanding the biological basis of host adaptability in the rice strain of fall armyworm.