An assessment of steinernema rarum as a biocontrol agent in sugarcane with focus on sphenophorus levels, host-finding ability, compatibility with vinasse and field efficacy

Authors: SILVA, MATEUS - Instituto Biologicio - Brazil; CARDOSO, JORGE - Instituto Biologicio - Brazil; FERREIRA, MARIA - Instituto Biologicio - Brazil; BALDO, FERNANDO - Instituto Biologicio - Brazil; SILVA, RAPHAEL - Instituto Biologicio - Brazil; CHACON-OROZCO, JULIE - Instituto Biologicio - Brazil; Shapiro Ilan, David; HAZIR, SELCUK - Adnan Mederes University; BUENO, CESAR - Instituto Biologicio - Brazil; GARRIGOS-LEITE, LUIS - Instituto Biologicio - Brazil

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2021
Publication Date: 5/28/2021
Citation: Silva, M.S., Cardoso, J.M., Ferreira, M.E., Baldo, F.B., Silva, R.S., Chacon-Orozco, J.G., Shapiro Ilan, D.I., Hazir, S., Bueno, C.J., Garrigos-Leite, L. 2021. An assessment of steinernema rarum as a biocontrol agent in sugarcane with focus on sphenophorus levels, host-finding ability, compatibility with vinasse and field efficacy. Agriculture, Ecosystems and Environment. 11/500. https://doi.org/10.3390/agriculture11060500.
DOI: https://doi.org/10.3390/agriculture11060500

Interpretive Summary: Nematodes are simple round worms. Entomopathogenic nematodes, also called beneficial nematodes, kill insect pests; they are environmentally-friendly bioinsecticides. In Brazil, countless insect species attack and damage sugarcane (, which is an extremely important crop plants considering its plantation in a vast area ofit is planted on more than 10 million hectares. Among these insects, the sugarcane billbug is of great importance as the larvae open tunnels in the rhizome of the plant, causing high damages and losses. This insect is attracted mainly to vinasse, which is the liquid fraction generated from the alcohol production and discarded on to the sugarcane fields for fertigation. In this study we tested which beneficial nematode species might be the best on for controlling surgarcane billbug and if the beneficial nematodes are affected by vinasse. Vinasse killed the beneficial nematodes when exposed directly, but vinasse was not harmful when the application was made in combination with other substrates (soil, straw, compost). The most efficacious nematode we found is called Steinernema rarum. The nematode was the best at finding the insect inside the rhizome and also showed the highest virulence (killing power). Therefore, there is potential to include the beneficial nematode, S. rarum, in a sustainable management plan for control of sugarcane billbugs.

Technical Abstract: In Brazil, countless insect species attack and damage sugarcane (Saccharum officinarum L.), which is an extremely important crop plants considering its plantation in a vast area ofit is planted on more than 10 million hectares. Among these insects, the sugarcane billbug, Sphenophorus levis (Coleoptera: Curculionidae) is of great importance as the larvae open tunnels in the rhizome of the plant, causing high damages and losses. This insect is attracted mainly to vinasse, which is the liquid fraction generated from the alcohol production and discarded on to the sugarcane fields for fertigation. Toward a novel control method for S. levis, the native entomopathogenic nematode S. rarum (Pam 25) was compared with S. carpocapsae (IL 1) and H. bacteriophora (HBEN01) in respect to their ability to search for larvae of two insect hosts (Galleria mellonella and S. levis) within the cane rhizome. The selected nematode S. rarum was also assessed for rate effects, its survival in vinasse, and field efficacy to control sugarcane pests S. levis, Hyponeuma taltula (Lepidoptera, Erebidae) and Leucothyreus alvarengai (Coleoptera: Melolonthidae). Steinernema rarum exhibited superior virulence to G. mellonella and S. levis larvae inserted into the cane rhizomes (75-78% mortality) compared to S. carpocapsae (30-53%) and H. bacteriophora (18-28%). Vinasse affected S. rarum when infective juveniles were suspended in the liquid compost for more than 6 hours, buthours but did not affect the nematode when kept on the straw and soil treated with the compost. Steinernema rarum tested at 1-3 x 108 IJs/ha on sugarcane field, caused > 74.1, 56.3 and 50.60% control of S. levis, L. alvarengai and >50% of H. taltula, respectively and L. alvarengai.