Behavioral and Physiological Plasticity Provides Insights into Molecular Based Adaptation Mechanism to Strain Shift in Spodoptera frugiperda

Abstract

How herbivorous insects adapt to host plants is a key question in ecological and evolutionary biology. The fall armyworm, (FAW) Spodoptera frugiperda (J.E. Smith), although polyphagous and a major pest on various crops, has been reported to have a rice and corn (maize) feeding strain in its native range in the Americas. The species is highly invasive and has recently established in China. We compared behavioral changes in larvae and adults of a corn population (Corn) when selected on rice (Rice) and the molecular basis of these adaptational changes in midgut and antennae based on a comparative transcriptome analysis. Larvae of S. frugiperda reared on rice plants continuously for 20 generations exhibited strong feeding preference for with higher larval performance and pupal weight on rice than on maize plants. Similarly, females from the rice selected population laid significantly more eggs on rice as compared to females from maize population. The most highly expressed DEGs were shown in the midgut of Rice vs. Corn. A total of 6430 DEGs were identified between the populations mostly in genes related to digestion and detoxification. These results suggest that potential adaptations for feeding on rice crops, may contribute to the current rapid spread of fall armyworm on rice crops in China and potentially elsewhere. Consistently, highly expressed DEGs were also shown in antennae; a total of 5125 differentially expressed genes (DEGs) s were identified related to the expansions of major chemosensory genes family in Rice compared to the Corn feeding population. These results not only provide valuable insight into the molecular mechanisms in host plants adaptation of S. frugiperda but may provide new gene targets for the management of this pest.

What Defines a Host? Oviposition Behavior and Larval Performance of Spodoptera frugiperda (Lepidoptera: Noctuidae) on Five Putative Host Plants

“…However, this preference for maize may vary according to S. frugiperda strain ( Meagher et al 2011 ). Ovipositional preference of S. frugiperda populations may be relatively plastic, with a shift of preference from maize to rice occurring within four generations of continuous feeding on rice ( Hafeez et al 2021 ). Although S. frugiperda did lay egg masses on the four other crops in our experiments, they laid many more eggs on the cage wall in the no-choice tests with these plants ( Supp Fig S1 [online only ]).…”

“…There are two genetically distinct ‘strains’ of S. frugiperda : the ‘corn’ and ‘rice’ strains ( Pashley et al 1985 , Nagoshi et al 2007a ); these are morphologically identical, but they differ in their host plant preferences ( Meagher et al 2011 ). The ‘corn’ strain prefers to oviposit on Z. mays , whereas the ‘rice’ strain prefers pasture grasses and rice for egg laying ( Pashley et al 1985 , Meagher et al 2011 , Hafeez et al 2021 ). Evidence so far indicates that both ‘strains’ are present in Australia ( Piggott et al 2021 ).…”

Characterization of Indoxacarb Resistance in the Fall Armyworm: Selection, Inheritance, Cross-Resistance, Possible Biochemical Mechanisms, and Fitness Costs

“…Smith), is a voracious insect pest native to the Western Hemisphere, particularly in South America [ 1 ]. It is one of the most rapidly spreading and highly invasive pests of maize across Africa and Asia [ 2 , 3 , 4 , 5 ]. S. frugiperda has become a pest species because of its biological characteristics such as polyphagy, concealed larval feeding habits, high reproductive capacity, adult dispersion, and multiple generations per year [ 3 , 4 , 5 ].…”

“…It is one of the most rapidly spreading and highly invasive pests of maize across Africa and Asia [ 2 , 3 , 4 , 5 ]. S. frugiperda has become a pest species because of its biological characteristics such as polyphagy, concealed larval feeding habits, high reproductive capacity, adult dispersion, and multiple generations per year [ 3 , 4 , 5 ]. The polyphagous fall armyworm feeds on more than 350 plants in such families, including Poaceae, Asteraceae, and Fabaceae [ 6 ].…”

Biological Activity of Phytochemicals from Agricultural Wastes and Weeds on Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

“…Recently, 353 species of host plants of S. frugiperda belonging to 76 families were identified, predominantly Poaceae, Asteraceae, and Fabaceae [8,9]. Nonetheless, corn, sorghum, rice, and cotton continue to be the most attacked crops by this larva [8,10]. The uncontrolled proliferation of S. frugiperda has reduced the yield of maize crops by up to 60%, while this number climbs to 100% in tropical areas [2,11,12].…”