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Low susceptibility of two collected slugs, Deroceras laeve and D.reticulatum to Egyptian Heterorhabditis strains as compared with imported EPNs, S. carpoapsae (All strain) and H. bacteriophora (HP88 strain).
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Deroceras laeve Müller and D. reticulatum Müller are serious slugs of field crops in Egypt. Chemical control using metaldehyde baits is still the main control tactic. In 2018, a survey of terrestrial slugs at Belbis district, Sharkia Governorate, Egypt failed to find the molluscicidal nematode, Phasmarhabditis hermaphrodita. Dead slugs produced onl...
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... in D. reticulatum percentage mortalities were 28.89, 26.78 and 32.11% with the same mentioned nematode strains. Whereas, tested entomogenous nematodes at concentrations of 1000 and 500 IJs/cm 2 showed lower mean percent mortality against D.leave and D. reticulatum, nevertheless imported EPNs nematodes were more effective than Egyptian strains (Table 3). The estimation of the results of the molluscicidal activity of Egyptian isolates namely H.bacteriophora (Serag1 strain), H.bacteriophora (Ht strain) and H. bacteriophora (Ar-4 strain) based on percentage mortalities when compared to S. carpocapsae (All strain) and H.bacteriophora (HP88 strain) at the three concentrations (2000, 1000 and 500 IJs/cm 2 ) showed less encourage usage as a specific biological control agent against D.leave and D.reticulatum. ...Citations
Mortality of imported entomopathogenic nematodes, Heterorhabditis bacteriophora (HP88),H. indica, and Steinernema carpocapsae (All) compared with local EPNs isolates, H. bacteriophora (Ar-4), H. bacteriophora (Serag1), and H. bacteriophora (Ht) alone or combined with the recommended dose of abamectin and fenamiphos on juvenile mortality percentages of two land snail species, Eobania vermiculata (Müller) and Monacha cartusinana (Müller) have been studied in a series of laboratory experiments.
Results exhibited that, mortality percentages and combined effect in the two land snail species were obviously influenced by EPNs species/strains, concentrations and exposure time. Among EPNs, H. bacteriophora HP88, H. indica, and H. bacteriophora (Ar-4) achieved the highest means of mortality percentages (66.67 & 70.0, 65.33 & 68.67 and 54.67 & 62.0 %) after three weeks of exposure with E. vermiculata and M. cartusinana. Whereas, S. carpocapsae (All) achieved the least mortality means (46.0 & 49.33 %) respectively.
On the other hand, application of 500 IJs of EPNs conjunction with RD of abamectin and fenamiphos surpassed use EPNs or RD alone to reach (69.00, 70.00, 62.67 %), in fenamiphos and abamectin reached 71.33, 67.33 and 62.67 % in E. vermiculata with H. bacteriophora HP88, H. indica and H. bacteriophora (Ar-4), respectively.
While the parallel values with M. cartusinana were 81.33, 84.00, 76.00 % in fenamiphos treatments and 72.00, 46.67, 67.33 % with abamectin treatments. CF of the tested EPNs with nematicides and their response varied according to periods of exposures. Synergistic and additive effects were exposed with EPNs and tested nematicides after one week, whereas additive or antagonistic effects were recorded after two and three weeks with examined land snail species.
Biological control using entomopathogenic nematodes (EPNs) is known as an ecofriendly strategy in integrated pest management. The terrestrial slug Parmacella ibera is a major pest of vegetables and citrus trees in north of Iran. The heavy costs and environmental concerns of synthetic molluscicides led the study to use EPNs, against the slug P. ibera. The present study was arranged to evaluate and compare the performance of EPNs, Steinernema feltiae, S. carpocapsae and Heterorhabditis bacteriophora on P. ibera population (mortality rate) and the feeding rate in vitro, and also its damage (seedlings establishment rate) in vitro. Phasmarhabditis hermaphrodita, as a slug parasite nematode, and also the metaldehyde, as a molluscicide, were used as positive controls. The results of the study showed that the highest mortality rate (%) and the seedlings establishment rate (%) of the slug population were observed in S. carpocapsae, S. feltiae and H. bacteriophora treatments, respectively. The feeding rate (%) of the slug declined in the treatments with H. bacteriophora, S. feltiae and S. carpocapsae, respectively. The mortality rate of the pest was enhanced by extending the exposure time and increasing levels of the nematodes. Therefore, it can be concluded that the EPNs S. carpocapsae, S. feltiae and H. bacteriophora are able to control the slug P. ibera population.
