Selection of Entomopathogenic Nematodes to Control Nymphs of <i>Haplaxius crudus</i> (Van Duzee) (Hemiptera: Cixiidae)

Abstract

Haplaxius crudus transmits the pathogen that causes Lethal wilt (ML for its name in Spanish), one of the main diseases that affects oil palms in Colombia. In its nymphal stage it feeds from grasses present at the plantations, and adults feed on oil palm leaves. With the objective of controlling the nymphal stage of H. crudus, the effectiveness of the following entomopathogenic nematodes was assessed: Steinernema colombiense, S. websteri, Steinernema sp. 1, Steinernema sp. 2, Heterorhabditis bacteriophora, Heterorhabditis sp. (Gua 31), Heterorhabditis sp. (Gua 236), Heterorhabditis sp. (CPHsp1301) and Heterorhabditis sp. (CPHsp1302). Pathogenicity was assessed under laboratory conditions using Petri dishes with roots of Paspalum virgatum. Virulence was assessed using mesh houses with PVC tubes and plastic trays with P. virgatum. Once the most virulent nematode was selected, three dosage levels were assessed under simulated field conditions, in order to select the most effective dosage. All assessed nematode species were pathogenic to nymphs of H. crudus, and nymph stage IV was the most susceptible stage, with death rates of over 80%. Regarding virulence, there were statistically significant differences among treatments (P≤0.05), producing nematode death rates between 28.3 and 88.2%. Heterorhabditis sp. (CPHsp1301), obtained from the soil of palm plantations, was selected because it caused a mortality rate of 78.4% with at a dosage of 1300 IJ/cm 2 in the sprayed area. The results are promising and further research should be performed under commercial oil palm plantation conditions.

Assessment of entomopathogenic nematodes and their symbiotic bacteria to control the stink bugs Euschistus heros and Dichelops melacanthus (Heteroptera: Pentatomidae) in the soybean-corn succession system

“…There have been some reports of EPNs serving as biological control agents against Hemiptera species on the leaves (Martínez-Córdoba et al, 2011;Naranjo et al, 2013;Niekerk and Malan, 2013;Platt et al, 2020), trunks/stems/shoots (Shapiro-Ilan and Mizell, 2012;Marrero et al, 2015;Guide et al, 2015;Guide et al, 2019) and soil (Leite et al, 2005;Melo et al 2006;Batista and Auad, 2010;Vieux and Malan, 2013;Mbata and Shapiro-Ilan, 2013;Batista et al, 2014;Alves et al, 2009;Guerrero & Pardey, 2019;Moussa et al, 2021;Zart et al, 2021). Susceptibilities of these insects range widely, with some species being more resistant than other usually tested insect hosts, requiring high rate of EPNs (100 IJs/cm 2 ) to provide > 70% mortality (Guide et al, 2015;Guide et al, 2019).…”

Bois noir management in vineyard: a review on effective and promising control strategies

“…An effective and novel integrated management against phytoplasma-associated diseases should include the identification and the control of phytoplasma insect vectors using biocontrol agents, such as EPNs and EPFs. In laboratory condition, Guerrero and Pardey (2019) showed the efficacy of EPNs belonging to the genus Steinernema and Heterorhabditis in controlling nymphs of Haplaxius crudus (Van Duzee), known to be the insect vector of ‘ Candidatus Phytoplasma palmae’.…”

“…), Cordyceps fumosorosea (Wize), Akanthomyces muscarius (Petch) were applied ( Langer et al., 2005 ; Moussa et al., 2021a ). However, field trials highlighted that environmental conditions, such as soil moisture and salinity, can affect the EPFs and EPNs activity ( Guerrero and Pardey, 2019 ); therefore, further studies to investigate their effectiveness under different climatic and environmental parameters, are necessary. Additionally, the possible effects on non-target species in vineyards should be accurately determined.…”

“…An effective and novel integrated management against phytoplasma-associated diseases should include the identification and the control of phytoplasma insect vectors using biocontrol agents, such as EPNs and EPFs. In laboratory condition, Guerrero and Pardey (2019) showed the efficacy of EPNs belonging to the genus Steinernema and Heterorhabditis in controlling nymphs of Haplaxius crudus (Van Duzee), known to be the insect vector of 'Candidatus Phytoplasma palmae '. Similar experimental trials aimed at reducing H. obsoletus population using EPFs and EPNs were conducted under laboratory and greenhouse conditions. Results showed a high H. obsoletus adult and nymph mortality when the nematodes Steinernema carpocapsae (Weiser), S. feltiae (Filipjev), Heterorhabditis bacteriophora Poinar and the fungi Metarhizium anisopliae (Metschn.…”

Population Parameters of Haplaxius crudus (Hemiptera: Cixiidae) under Semi-Controlled Conditions

“…There are some reports of natural enemies of H. crudus present in Mexico and Florida (USA), including spiders of the genus Theridion (Walckenaer) (Araneae: Theridiidae) and the ant Solenopsis invicta (Buren) (Hymenoptera: Formicidae) [13,14], parasitic mites of the genera Leptus (Latreille) (Trombidiformes: Erythraeidae) and Erythraeus (Latreille) (Trombidiformes: Erythraeidae) [14] and the fungus Hirsutella citriformis (Speare) (Hypocreales: Ophiocordyetaceae) [14,15]. In Colombia, it was established that a strain of the fungus Metarhizium anisopliae (Metchnikoff) Sorokin (Hypocreales: Clavicipitaceae) affects adults and nymphs of H. crudus.…”