Movement of Heterorhabditis amazonensis and Steinernema arenarium in search of corn fall armyworm larvae in artificial conditions

Abstract

Spodoptera frugiperda (smith, 1797) (Lepidoptera: Noctuidae) is considered to be the main pest of maize crops in brazil. Entomopathogenic nematodes (EPN) may be used to control this pest and exhibit different, unique abilities to search for their hosts. the movement of EPN in relation to S. frugiperda was evaluated. to test for horizontal movement, a styrofoam enclosure filled with sand was divided into segments, nematodes were placed at the entrance to the enclosure and a larva was placed at the end of each division. the same approach was used to evaluate vertical movement; however, PVc pipes were used in this case. In general, the mortality was inversely proportional to the initial distance between host and nematodes. In the vertical displacement test, both nematodes were able to kill the larvae up to a distance of 25 cm. therefore, the infective juveniles of H. amazonensis and S. arenarium can search out, infect and kill larvae of S. frugiperda at distances of up to 60 cm and 25 cm of horizontal and vertical displacement, respectively.

Soil texture, infective juvenile concentration, and soil organic matter influence the efficacy of Steinernema feltiae isolate Lican Ray

“…Furthermore, they achieved vertical distances of 70, 50 and 30 cm in loam, sandy loam and clay soil, respectively. Other studies found similar results with vertical movement of S. feltiae on the host G. mellonella (Neumann and Shields, 2006), also of S. carpocapsae on Anastrepha obliqua (Diptera: Tephritidae) (Toledo et al, 2009), and vertical and horizontal of Heterorhabdits amazonensis and Steinernema arenarium on Spodoptera frugiperda (Lepidopera: Noctuidae) (Andaló et al, 2012). In addition, in our study, mortality of G. mellonella decreased with the extreme soil textures evaluated.…”

Eliciting maize defense pathways aboveground attracts belowground biocontrol agents

“…Likewise, because H. amazonensis does not recruit to mechanially damaged plants, our results suggest that mechanical damage alone is not sufficient to stimulate a plant defense response. Indeed, monitoring of plant defense pathway stimulation by aboveground herbivory on the part of the entomopathogenic nematode H. amazonensis may hold adaptive significance; feeding aboveground by the adult D. speciosa indicates a greater likelihood of eventually finding suitable larval hosts, especially for cruiser nematodes like H. amazonensis which can travel large distances belowground in search of food2829. As adult D. speciosa recruit to herbivorized plants where they are likely to encounter other members of their species, they are apt to mate and reproduce on the same plant, letting the eggs fall to soil in the immediate area.…”

Searching for Better Methodologies for Successful Control of Termites Using Entomopathogenic Nematodes

“…To evaluate the tolerance of IJs of indigenous EPNs to environmental stresses, the nematodes are subjected to temperatures varying between −5 and 40°C [38,[112][113][114][115][116], to hypoxia [38,117], to dehydration/desiccation for up to 75% RH [118,119], and to ultraviolet radiation stress (for example, at 340 nm, [120]). The persistence or longevity of indigenous EPN species in the soil [121], their genetic improvement, their infectivity [118,119,122], trehalose content/accumulation [123], motility, development, virulence, and reproduction inside insect hosts [124] under environmental stresses are some traits that are often evaluated.…”

“…At high temperatures of ca. 35-40°C, nematode physiological activity is high, increasing the consumption of its stored energy and resulting in limited shelf life [112] and low searching [137] and pathogenicity [138] potential of the nematodes. Hang et al [124] observed nematode IJs' development to adult at 13, 18, 24, 30, and 35°C and progeny production at 18, 24, and 30°C but not at 13 or 35°C.…”