Spodoptera frugiperda Uses Specific Volatiles to Assess Maize Development for Optimal Offspring Survival

Abstract

Spodoptera frugiperda, a major global agricultural pest, poses significant challenges to chemical control methods due to pesticide resistance and environmental concerns, underscoring the need for sustainable management strategies. Attractants based on host plant volatiles offer a promising eco-friendly approach, but their development for S. frugiperda is hindered by limited research on host recognition mechanisms. This study reveals that female S. frugiperda preferentially oviposit on maize at the seedling stage. Using electrophysiological techniques, we identified p-xylene and (+)-camphor from seedling-stage maize volatiles as key compounds eliciting strong responses in female S. frugiperda. Behavioral assays confirmed that these compounds (p-xylene at the concentration of 5%, 10%, and 20% and (+)-camphor at 1%, 5%, and 10%) significantly attract females, establishing them as the key odor cues for host selection. Moreover, these volatiles are more abundant in seedling-stage maize, suggesting that S. frugiperda assesses maize growth stages based on their concentrations. Importantly, larvae reared on seedling-stage maize exhibited higher survival rates than those on later-stage maize, indicating that oviposition site selection directly affects offspring fitness. These findings demonstrate that S. frugiperda uses p-xylene and (+)-camphor to evaluate maize development and select suitable oviposition sites, thereby enhancing larval survival. This study provides a foundation for developing targeted attractants for S. frugiperda and highlights the seedling stage as a critical period for implementing pest control measures, particularly in autumn maize production, given the higher pest population density during this phase.

Keywords: (+)-camphor; Spodoptera frugiperda; growth stage; host recognition mechanism; maize; p-xylene.

Figure 1

Experimental device for oviposition selection of S. frugiperda. Note: The number in the figure is the position of the leaves.

Figure 2

Olfactory selection of female S. frugiperda to maize volatiles at different stages. Note: In the histogram, *** indicates a significant difference (p < 0.01) (chi-square test). n represents the total number of tested adults.

Figure 3

Olfactory selection of male S. frugiperda to maize volatiles at different stages. Note: ns in the histogram indicates that the difference is not significant (p > 0.05) (chi-square test). n represents the total number of tested adults.

Figure 4

Oviposition selectivity of female S. frugiperda to maize at different growth stages. Note: Number of choices represents the number of adults selected FS vs. MS, STS vs. FS, and SS vs. STS. The numbers in parentheses represent the total number of test insects for each treatment. *** in the histogram indicates that the difference is significant (p < 0.01) (chi-square test).

Figure 5

Effects of feeding on maize leaves at different growth stages on the growth, development, and reproduction of S. frugiperda: (A) survival rate; (B) duration of the larval stage; (C) duration of the pupal stage; (D) larval weight; (E) pupal weight; (F) pupation rate; (G) single female oviposition; (H) hatch rate. Note: Different letters in the graph indicate that there are significant differences between different treatments (p < 0.05) (LSD test) (mean ± standard error).

Figure 6

GC-EAD response of female S. frugiperda to maize volatiles. Note: The numbers in the figure are two active components of the SS maize volatiles.

Figure 7

Mass spectra of No. 1 and No. 2 compounds in the corn volatiles (A): p-xylene; (B): (+)-camphor.

Figure 8

Neuronal response of one antennal sensilla of S. frugiperda. Note: The red arrows indicate the position of the stimulus.

Figure 9

Responses of different neurons in the antennal sensilla of S. frugiperda to volatile active components of the host. Note: ORN a and ORN b in the figures represent two kinds of neurons. The spike difference of 1 s before and after stimulation was counted, and the error line was the standard error.

Figure 10

Olfactory behavior of S. frugiperda female adults in response to three different concentrations of compounds: (A) p-xylene; (B) (+)-camphor. Note: *** indicates a significant difference (chi-square test) (p < 0.01). n represents the total number of tested adults.