Attack and defense movements involved in the interaction of Spodoptera frugiperda and Helicoverpa zea (Lepidoptera: Noctuidae)

Abstract

The fall armyworm, Spodoptera frugiperda (J. E. Smith) and the corn earworm, Helicoverpa zea (Boddie) are among the main pests of maize. Both species exhibit cannibalistic behavior and quite often share the same feeding guild in maize (maize ears), which can result in several interspecific and intraspecific interactions. Paired interaction scenarios of intraspecific and interspecific larvae were assessed in arenas in the presence and absence of food to characterize movements resulting from interactions of these insects. There was a difference in the frequency of behavioral movements in all the interactions, except for S. frugiperda in the presence of food. Head touching and recoiling were the predominant movements in most of the interaction scenarios. Spodoptera frugiperda exhibited a predominance of defensive movements when competing against H. zea in the same instars. Cannibalism and predation occurred frequently in interactions involving 6th instar of H. zea against opponents in 4th instar. Larvae of H. zea show a higher aggressive movement than S. frugiperda. The larvae of S. frugiperda take advantage during the interactions, although they present more defensive movements compared to H. zea. This study provides relevant information regarding the interaction of these species and intraguild interaction, which might influence the population dynamics and the competitive displacement of pest species that share the same ecological niche. Keywords: Intraguild interaction, Ethogram, Fall armyworm, Corn earworm, Aggressive Key message• The intraguild interactions of fall armyworm and corn earworm are still unclear; moreover they exhibit cannibalistic/ predation behavior and may share the same feeding niche in maize. Our studies have indicated the main movements in interactions between these species.• Fall armyworm took advantage of corn earworm during the contests, although it presented more defensive movements. • This is relevant information for population dynamics, displacement of species, and it has implications for transgenic maize insect resistance management strategies for these species.

Shifts in Ecological Dominance between Two Lepidopteran Species in Refuge Areas of Bt Cotton

“…The intra-and interspecific competition of larvae depends on the instar and, therefore, the stage of larval development [24,[39][40][41]. Thus, we propose that the third reason could be due to the faster development of H. armigera larvae, promoting larger larvae in a short time and being more competitive in relation to S. frugiperda in the conditions of higher densities, because the consumption of its competitor can promote the intake of readily digestible and metabolizable food resources.…”

“…Spodoptera frugiperda and H. armigera are cannibalistic in their larval stage [24]. At the field level, these pests can infest the plant simultaneously during the season and feed on the same cotton structures, such as squares, flower, bolls, and blooms.…”

Intraguild interactions and behavior of Spodoptera frugiperda and Helicoverpa spp. on maize

“…In this scenario, larvae of S. frugiperda might be able to survive because of their ability to escape from aggressive interactions, such as moving away from the competitor, and/or through other defensive or offensive mechanisms. 57 In fourth versus second and fourth versus fourth instar interactions, the high survival of S. frugiperda also indicates that the species is not negatively affected by H. armigera in interactions on non-Bt maize. Similarly to H. zea, moths of H. armigera prefer to oviposit on the reproductive parts of maize plants, 20 and again because S. frugiperda colonizes vegetative plant stages, the competitive advantage of S. frugiperda over H. armigera might be more accentuated under natural conditions in non-Bt maize.…”

“…When larvae of S. frugiperda were less developed than H. armigera (second versus fourth instar), survival of S. frugiperda decreased, although it did not differ from survival during second versus fourth intraspecific interactions, which indicates the capacity of S. frugiperda to survive in an intraguild interaction with H. armigera even when smaller than the competitor. In this scenario, larvae of S. frugiperda might be able to survive because of their ability to escape from aggressive interactions, such as moving away from the competitor, and/or through other defensive or offensive mechanisms . In fourth versus second and fourth versus fourth instar interactions, the high survival of S. frugiperda also indicates that the species is not negatively affected by H. armigera in interactions on non‐ Bt maize.…”

Research on the Attack and Defense Techniques of Chinese Women's Basketball Team and the Top Four Teams in the First Women's Basketball World Cup

“…It is suggested to actively introduce high-level foreign athletes, and encourage domestic athletes to go abroad for competitions, which will help them accumulate experience in large-scale competitions, and promote the improvement of personal ability. The Chinese team should also pay close attention to training more talented people, save reserve strength for the Chinese team, and ensure the long-term development of the team [13].…”