Mortality of Four Stored Product Pests in Stored Wheat When Exposed to Doses of Three Entomopathogenic Nematodes

Abstract

The insecticidal effect of Heterorhabditis bacteriophora Poinar (Nematoda: Heterorhabditidae), Steinernema carpocapsae (Weiser) (Nematoda: Steinernematidae), and Steinernema feltiae (Filipjev) (Nematoda: Steinernematidae) against Mediterranean flour moth, Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) (larvae), lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) (adults), rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) (adults), and confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) (adults and larvae) was examined under laboratory conditions in wheat, Triticum aestivum L. The nematodes were applied at the following doses: 0 (control), 100, 500, 1,000, 1,500, 5,000, 10,000, and 20,000 infective juveniles (IJs) per ml, corresponding to 10, 50, 100, 150, 500, 1,000, and 2,000 IJs per insect, and their infectivity was tested at 20 and 30 degrees C after 4 and 8 d of exposure. For E. kuehniella larvae wheat treatments with S. feltiae provided mortality that ranged from 36.7 to 78.3% whereas no mortality was noted in the treatment with S. carpocapsae at 100 IJs per ml at 20 or at 30 degrees C. Also, at 20 degrees C, in wheat treated with H. bacteriophora at 100 IJs per ml, very few larvae were dead. For R. dominica adults, at 20 degrees C, the mortality of adults in wheat treated with S. feltiae and S. carpocapsae did not exceed 23.3 and 41.7%, respectively, at 20,000 IJs per ml, with no significant differences among doses. In the case of S. oryzae adults, the mortality was very low at all doses, and temperatures and did not exceed 9%. Mortality of T. confusum adults did not exceed 17% regardless of the entomopathogenic nematode species tested. In contrast, mortality of T. confusum larvae was notably higher and exceeded 56% in wheat treated with 10,000 or 20,000 IJs per ml of S. feltiae at 20 degrees C. Unlike S. feltiae and S. carpocapsae, the application of H. bacteriophora resulted in lower mortality levels. Generally, the increase of temperature reduced the mortality levels of the T. confusum larvae. In most cases, the efficacy level of the tested entomopathogenic nematode species increased with the dose and decreased with the increase of temperature.

Entomopathogenic Nematodes (Nematoda: Rhabditida) in Slovenia: From Tabula Rasa to Implementation into Crop Production Systems

“…We expect that satisfactory mortality rates of insects are the result of applying EPNs several times in a row. When applying EPNs several times in a row, one should of course take into account the economic aspect of food production (Athanassiou et al, 2010;Laznik et al, 2010c). The results of our study have shown that feeding of adult specimens of the greenhouse whitefly influences also the average mass of cucumbers (table 2) (Laznik et al, 2011).…”

Biocontrol potential of entomopathogenic nematode species against Tribolium confusum (Jac.) (Coleoptera: Tenebrionidae) and Rhyzopertha dominica (Fab.) (Coleoptera: Bostrichidae) under laboratory conditions

“…Early studies evaluated the virulence of Steinernema feltiae Filipjev (formerly Neoplectana carpocapsae) (Alikhan et al 1985) and S. carpocapsae Weiser (Wójcik 1986) against adults of S. granaries. Various studies have also been conducted for the evaluation of the virulence of EPNs against the stored grain pest T. castaneum (Ramos-Rodríguez et al 2006) and the confused flour beetle, Tribolium confusum (Alikhan et al 1985;Athanassiou and Kavallieratos 2010;Rumbos and Athanassiou 2012). Larvae of T. castaneum were highly susceptible to three steinernematid species, i.e., S. feltiae, S. carpocapsae, and S. riobrave, whereas for pupae and adults, susceptibility was speciesdependent (Ramos-Rodríguez et al 2006).…”

“…However, most studies agree on the poor infectivity of EPNs against T. confusum adults (Athanassiou et al 2008;Rumbos and Athanassiou 2012). R. dominica larvae develop inside the kernel; hence, studies with EPNs have focused on the susceptibility of the freeliving adult stage, which exhibited low to moderate susceptibility (Ramos-Rodríguez et al 2006;Athanassiou and Kavallieratos 2010). Trdan et al (2006) also studied the effect of two heterorhabditid species, Heterorhabditis bacteriophora Poinar and H. megidis Poinar, Jackson and Klein, with H. megidis being the least efficient.…”

First report of the isolation of entomopathogenic nematode Steinernema australe (Rhabditida: Steinernematidae) from South Africa

“…7,8 Entomopathogenic nematodes have been successfully applied as effective biological control agents against some significant lepidopteran, dipteran and coleopteran insects of commercial crops. 9 The effectiveness of entomopathogenic nematodes depends on both the nematodes' capability to locate, recognise and invade a host, and the virulence of the bacteria to susceptible hosts. 9 Entomopathogenic nematodes infect vulnerable insect hosts while in the free-living, non-feeding infective juvenile arrested developmental stage.…”

“…9 The effectiveness of entomopathogenic nematodes depends on both the nematodes' capability to locate, recognise and invade a host, and the virulence of the bacteria to susceptible hosts. 9 Entomopathogenic nematodes infect vulnerable insect hosts while in the free-living, non-feeding infective juvenile arrested developmental stage. Once in the gut of the host, they regurgitate or release their associated pathogenic bacteria into the haemocoel, resulting in septicaemia or toxaemia in the host within 24-48 h. 4 Upon infection, Steinernema infective juveniles develop into either feeding males or amphimictic females.…”