Insecticidal effect of entomopathogenic nematodes and the cell-free supernatants from their symbiotic bacteria against different larval instars of Agrotis segetum (Denis & Schiffermüller) (Lepidoptera: Noctuidae) (original) (raw)
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International Journal of Plant & Soil Science
The tobacco caterpillar, Spodoptera litura is a polyphagous pest with attacking almost 290 host plants species globally causing a wide range of yield losses to the agricultural crops. In this investigation symbiotic bacteria of entomopathogenic nematodes were evaluated for their insecticidal activity against larvae of S. litura under lab conditions. The intact cell suspension and cell-free extract were screened for their bacterial pathogenicity and the results showed mortality of larvae after 24h of post treatment. The percent mortality treated with intact cell suspension was significantly higher in larvae treated with EPB3 strain with 90% which was on par with the reference strain Bacillus thuringiensis after 72h of post treatment. There is no significant difference among the larval mortality treated with cell-free supernatant. The virulence test was carried out to find out the LD50 and LT50 against the larvae and the results showed that EPB3 and B. thuringiensis required 104 CFU f...
ENTOMOPATHOGENIC NEMATODES : A HIDDEN ENEMY OF INSECT PESTS
Entomopathogenic nematodes (EPN's) are attractive, organic alternatives for controlling a wide range of insect pests and they are utilized in classical, conservation and augmentative biological control programs. The history of entomopathogenic nematology is briefly reviewed. In general, EPN's are soil borne and generally gets mutually associated with a bacterium which is responsible for pesticidal actions and its life cycle of consist of five developmental stages. The two most studied species of EPN's are Steinernematidae and Heterorhabditidae families which has mutualistic association with bacteria of genus Xenorhabdus and Photorhabdus, respectively. The virulence mechanisms of the symbiotic bacteria were depending upon antibiotic properties, phase variants and impeding host defense responses. In the laboratory use and small scale field experiments, in vivo production of EPNs appears to be the appropriate method. In vitro technology is used when large scale production is needed at reasonable quality and cost. The efficacy of EPNs can be enhanced through proper production technology, storage mechanism, application technology etc. The scientific community, academician and industrialist are interest to development of new bio-insecticides, which are environmentally friendly. The concerns for the environment and human health and to reducing the risks connected with chemicals, the present review article focused on importance of EPN's in insect pests management, its life cycle, virulence mechanism, mass production technology, commercial product and storage, application technology, guideline for field application and its ccompatibility with insecticide and fertilizers are briefly reviewed.
Role of entomopathogenic nematodes in the management of insect pests
2014
Entomopathogenic nematodes (EPNs) of the genera Heterorhabditis and Steinernema are obligate and lethal insect parasites. They have the greater potential to be developed as a microbial agent for the management of various insect pests of orchard, vegetables, ornamental plants and turf grasses. The third stage juvenile i.e. the infective juvenile along with symbiotic bacteria (Xenorhabdus spp. in Steinernema spp. and Photorhabdus spp. in Heterorhabditis spp.) enters into the insect body through natural openings or sometimes by penetration through intersegmental membrane. The relationship between nematode and bacteria is an example of true mutualism and from this relation both the organisms are benefited. This nematode-bacterium complex causes the death of insect pests within 24–72 hours. Mass rearing of Steinernematid and Heterorhabditid nematodes can be done in vivo in insect hosts and in vitro in solid medium or in liquid medium. For in vivo production Galleria mellonella larvae are...
Journal of Nematology, 2021
Entomopathogenic nematodes (EPN) are excellent biocontrol agents against various insect pests. Novel biotechnological approaches can enhance their utility against insects above-ground, opening a new venue for selecting superior EPN against certain insects. We hypothesize that different populations of the same species but from different origins (habitat, ecoregion) will differ in their virulence. This study aimed to evaluate the virulence of various EPN populations against two pests of worldwide incidence and damage to high value crops: Frankliniella occidentalis (Thysanoptera: Thripidae) and Tuta absoluta (Lepidoptera: Gelechiidae). We tested 10 EPN populations belonging to three EPN species: Heterorhabditis bacteriophora (Koppert, MG-618b, AM-203, RM-102), Steinernema feltiae (Koppert, RS-5, AM-25, RM-107), and Steinernema carpocapsae (Koppert, MG-596a). Each EPN population was tested at two concentrations. Frankliniella occidentalis was tested at 160 and 80 IJs/cm 2 and T. absoluta at 21 and 4 IJs/cm 2. Control treatments followed the same experimental procedure but only adding distilled water. Overall, whenever different, higher IJs concentration resulted in lower adult emergence, higher larval mortality, and shorter time to kill the insects. Considering the low concentration, S. feltiae provided the best results for both insects and instars investigated, while H. bacteriophora and S. carpocapsae required a high concentration to reach similar or slightly better results. Differences among populations of each of the species were detected, but only the native populations of H. bacteriophora populations showed consistently higher control values against both insects/instar compared with the commercial one. Differences among S. feltiae and S. carpocapsae populations depended on the IJs concentration, insect, and instar. We consider S. feltiae a very promising species for their application against F. occidentalis and T. absoluta, with the Koppert population as the most consistent among the populations tested. Specific EPN-populations of S. carpocapsae and H. bacteriophora were good candidates against certain instar/insects at high concentrations. This study emphasized the importance of intraspecific variability for EPN virulence.
Journal of Nematology
Entomopathogenic nematodes (EPN) are excellent biocontrol agents against various insect pests. Novel biotechnological approaches can enhance their utility against insects above-ground, opening a new venue for selecting superior EPN against certain insects. We hypothesize that different populations of the same species but from different origins (habitat, ecoregion) will differ in their virulence. This study aimed to evaluate the virulence of various EPN populations against two pests of worldwide incidence and damage to high value crops: Frankliniella occidentalis (Thysanoptera: Thripidae) and Tuta absoluta (Lepidoptera: Gelechiidae). We tested 10 EPN populations belonging to three EPN species: Heterorhabditis bacteriophora (Koppert, MG-618b, AM-203, RM-102), Steinernema feltiae (Koppert, RS-5, AM-25, RM-107), and Steinernema carpocapsae (Koppert, MG-596a). Each EPN population was tested at two concentrations. Frankliniella occidentalis was tested at 160 and 80 IJs/cm 2 and T. absoluta at 21 and 4 IJs/cm 2. Control treatments followed the same experimental procedure but only adding distilled water. Overall, whenever different, higher IJs concentration resulted in lower adult emergence, higher larval mortality, and shorter time to kill the insects. Considering the low concentration, S. feltiae provided the best results for both insects and instars investigated, while H. bacteriophora and S. carpocapsae required a high concentration to reach similar or slightly better results. Differences among populations of each of the species were detected, but only the native populations of H. bacteriophora populations showed consistently higher control values against both insects/instar compared with the commercial one. Differences among S. feltiae and S. carpocapsae populations depended on the IJs concentration, insect, and instar. We consider S. feltiae a very promising species for their application against F. occidentalis and T. absoluta, with the Koppert population as the most consistent among the populations tested. Specific EPN-populations of S. carpocapsae and H. bacteriophora were good candidates against certain instar/insects at high concentrations. This study emphasized the importance of intraspecific variability for EPN virulence.
Insects, 2021
The meadow spittlebug Philaenus spumarius (Hemiptera: Aphrophoridae) is the primary vector of Xylella fastidiosa (Proteobacteria: Xanthomonadaceae) in Europe, a pest–disease complex of economically relevant crops such as olives, almonds, and grapevine, managed mainly through the use of broad-spectrum pesticides. Providing environmentally sound alternatives to reduce the reliance on chemical control is a primary challenge in the control of P. spumarius and, hence, in the protection of crops against the expansion of its associated bacterial pathogen. Entomopathogenic nematodes (EPNs) are well-known biocontrol agents of soil-dwelling arthropods. Recent technological advances in field applications, including improvements in obtaining cell-free supernatant from their symbiotic bacteria, allow their successful implementation against aerial pests. Thus, this study aimed to evaluate, for the first time, the efficacy of EPN applications against nymphal instars of P. spumarius. We tested four...
Egyptian Journal of Biological Pest Control, 2018
The black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) is considered to be one of the serious polyphagous pests that spend a large part of its life in the soil environment, where many microorganisms live including entomopathogenic nematodes (EPNs) (Rhabditida: Steinernematidae and Heterorhabditidae). EPNs have been long used for suppressing the soil-dwelling insects like cutworms and are successful biological control agent against A. ipsilon larvae. In the present study, the efficacy of local EPNs isolates against the fourth larval instar of A. ipsilon was evaluated at different concentrations (10, 25, 50, 100 IJs/larva/Petri dish and 25, 50, 100 IJs/cm 2 soil) in two different experiment environments including filter papers in Petri dishes and soil in plastic containers under laboratory conditions at 25 ± 1°C. Larval mortalities of A. ipsilon were recorded first, second, third, and fourth day post inoculation where the mortality rates increased by increasing the concentrations. The maximum mortality rate (100%) was reached within 2 days after inoculation, inoculating the Heterorhabditis bacteriophora FLH-4-H and H. indica 216-H isolates at concentrations of 50 and 100 IJs/cm 2 , in the plastic container experiment. The highest mortality rate (90%) was obtained by Steinernema carpocapsae E76-S isolate at a concentration of 100 IJs/larva/Petri on the fourth day after inoculation, in the Petri dish experiment. The lethal concentration values (LC 50 and LC 90) of the A. ipsilon larval population were 52 IJs and 129 IJs, respectively, for S. feltiae E76-S isolate in the Petri dish tests. In the plastic container experiment, the lowest LC 50 and LC 90 values found to be 17 IJs and 23 IJs, respectively, for H. bacteriophora FLH-4-H isolate. The results showed that all indigenous EPN isolates had good potentials in the management of A. ipsilon.
Revista Colombiana de Entomología
This work aims to evaluate the potential of Brazilian isolates of entomopathogenic nematodes through the selection of isolates for Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae). In order to analyze the susceptibility at different instars of the insect and different concentrations, to investigate the in vivo production of these isolates, and to perform greenhouse tests in the Laboratory of Entomologia e Controle Microbiano of Universidade Estadual do Norte do Paraná, Brazil. Selection tests were carried out with nine isolates, and those that caused greater percentages of insect mortality were used in concentration tests (0, 50, 100, 150, 200 Infective Juveniles (IJs)/cm2), with different instars of the insect (2nd, 3rd, 4th, 5th, 6th instars and pupa), in the in vivo production of A. ipsilon larvae, and in pathogenicity tests in a greenhouse. In the selection test, the isolate CH3 (Steinernema sp.) caused 100 % of mortality in A. ipsilon, and the isolates GL (Heterorhabditis am...