جستجوی مقالات مرتبط با کلیدواژه "heterorhabditis" در نشریات گروه "گیاهپزشکی"

The aim of this study was to collect and identify entomopathogenic nematodes native to Iran and to evaluate their pathogenicity on honeycomb moth larvae (Galleria mellonella).

Thirteen isolates of entomopathogenic nematodes were collected from different provinces of Iran and identified based on morphological characters. The percentage mortality of G. mellonella larvae infected with these isolates at 25 ± 1 and 32 ± 1 °C was determined in a one-to-one assay, and the ability of the isolates to find a target and the mortality of the insect in the sand column test were determined.

Seven isolates of Heterorhabditis bacteriophora, two isolates of Steinernema feltiae, and five isolates of S. carpocapsae were identified. The ability of isolates of all three nematode species to penetrate the insect's body has been shown to be up to 93% within 48-72 hours post-infection at 25 ± 1°C. The optimum temperature for the biological activity of the identified isolates was 25±1°C. S. carpocapsae found a target faster than the other two species in the sand column test.

Isolates of S. carpocapsae have higher potential in targeting and pathogenicity of honeycomb moth larvae than the other two nematode species.

In the recant decade, biopesticides with entomopathogenic nematodes (EPNs) have been developed with using different methods and materials. But the production of such biopesticides has always accompanied by some limitations such as low quality of the final product, and reducing the efficacy under field conditions. Recently, significant progress has been made in increasing in the survival time of these products. Applying two types of formulations, water dispersible granules and calcium alginate capsules, has increased the EPN survival time from 7 days to 180 days. As compare to aqueous formulation, the formulations based on the use of insect cadavers with EPNs, showed higher efficiency in pest control. New methods of the mass production of EPNs, using automated production lines and the use of new additives with better properties for field applications and methods in increasing the infectivity of these nematodes in pests are discussed in this article.

Entomopathogenic nematodes (EPNs) are one of the most important biocontrol agents. The identification of these agents has become very important issue due to the developing trend of their applications in the recent decades. A survey for isolation of EPNs was conducted in Bojnourd region, from three different habitats. Subsequently, morphological and molecular characteristics as well cross breeding tests were used to identify those native isolates. Among 50 soil samples, 5 samples were positive including 10 populations. Both Steinernema and Heterorhabditis genera were isolated using Galleria trap method. According to morphological and morphometric characters, four isolates, namely Boj1, Boj7, Boj8 and Boj9 were from "feltiae" species group of Steinernema. Another isolate, HBoj was a member of "bacteriophora" species group of Heterorhabditis. The phylogenetic analysis on sequence data of ITS showed that Boj1, Boj7, Boj8 and Boj9 attributed to “feltiae” group, while HBoj isolate belonged to “bacteriophora” group. Reconstruction of phylogenetic trees using ITS sequences showed that four isolates, Boj1, Boj7, Boj8 and Boj9 were grouped in a clade with other species of "feltiae" group (of Steinernema). Phylogenetic analysis on those genes for HBoj isolate grouped this isolate with H. bacteriophora species in a clade. Crossbreeding tests between Boj1, Boj7, Boj8 and Boj9 isolates and reference strain of S. feltiae showed that Boj1 belongs to the S. feltiae species. The other three isolates (Boj7, Boj8 and Boj9) were species from Steinernema genus. Current survey is the first study on native populations of EPNs in North Khorasan.

Most nematodes are free-living. They live in oceans, fresh waters and soil and feed on bacteria, fungi and other nematodes. Some are predators and some are parasites of plants and animals. Some of the latter group are insect-associated. There are different types of relations between insects and nematodes. Beneficial nematodes that cause disease in insects are referred to as “entomopathogenic” and have the ability to kill the insects. Entomopathogenic nematodes from the genera Stein¬ernema and Heterorhabditis have proven to be the most effective as biological control organisms. Only the infective juvenile stage of entomopathogenic nematodes will survive in the soil, find and penetrate insect pests. In this paper, different types of association between nematode and insect with emphazing on entomopathogenic nematode species have been reviewed.