موقع الدكتورة / مروة عزمى جنينة

 IMPACT OF EIGHT  BACTERIAL ISOLATES OF BACILLUS THURINGIENSIS AGAINST THE TWO LAND SNAILS, Monacha cantiana AND Eobania vermiculata (GASTROPODA: Helicidae).

Marwa, A. M. Genena and Fatma, A. M. Mostafa

Agric. Zoology Dept., Fac. Agric., Mansoura Univ., Mansoura,Egypt.

  ABSTRACT

Under laboratory conditions, eight native bacterial isolates of Bacillus thuringiensis, were tested for their molluscicidal activity against the two land snails, Monacha  cantiana (Montagu) and Eobania vermiculata (Muller) at a constant concentration (7×10­­­­­⁶ cfu/ ml) using three methods of application. Results revealed that all tested isolates applied via food or soil had no adverse effect on the tested land snails and resulted no mortality in M. cantiana  and E. vermiculata as well.  However, results clearly indicate the molluscicidal properties of the tested isolates and identify Bt-k64  ,Bt- B33 as well as Bt- W123  as potentially effective against M. cantiana and  E. vermiculata when bacterial isolates were introduced to snails via food and soil simultaneously (concomitant treatment). For eight bacterial isolates, the percentage mortality ranged from 33% to 86.6% for the land snail, M. cantiana , while in the land snail, E. vermiculata the percentage mortality ranged from 6.6% to 53%. after four weeks of treatment. B. thuringiensis  designated as Bt- K64 was the most effective one against the two land snails, M. cantiana and E. vermiculata with percentage mortality 86.6% and 53.0% , respectively whereas, B. thurinigensis  designated as Bt- B123 was the least toxic isolate  with mortality 33% and 6.6% respectively. M. cantiana was more sensitive to the tested isolates than Eobania vermiculatum.

       Moreover, the molluscicidal activity of the three isolates of the bacterium, B. thurinigensis designated as  Bt-W123 ,  Bt-B33  and Bt-K64  at  three concentrations (1×10­­­­­⁶ , 1×10⁷ and 1×10⁸ cfu/ ml) against M. cantina under laboratory condition at 15튏3 and 60 5% RH. was undertaken.  Isolate Bt –B33 and isolate Bt –W123 showed higher toxicity  to the target snail than isolate Bt –K64 with mortality increasing with an increase in the concentrations of isolates as well as the period of exposure. At the highest concentration ( 1×10⁸) the bacterial isolate Bt –B33 was the most toxic which killed 53% of the land snail M. cantiana after two weeks from treatment and     and 86.4% after three and four weeks of experiment.

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MOLLUSCICIDAL ACTIVITY OF SIX PESTICIDES AGAINST THE TWO LAND SNAILS, Monacha cantiana AND Eobania vermiculata (GASTROPODA: Helicidae) UNDER LABORATORY CONDITIONS.

Marwa, A. M. Genena,   and Fatma, A. M. Mostafa

Agric. Zoology Dept., Fac. Agric., Mansoura Univ., Mansoura, Egypt.

ABSTRACT

The following six pesticides namely, bensultap, chlorpyrifos-ethyl, deltamethrin, diazonixy, lambda-cyhalothrin and methomyl were laboratory tested for their molluscicidal activity against the two land snails, Monacha cantiana (Montagu) and Eobania vermiculata (Muller) as poisonous baits at a constant concentration of 2%. Results revealed the toxic effect of all tested pesticide baits with mortality percentage increasing with an increase in the period of exposure. It was evident that deltamethrin belonging to pyrethroid group exceeded other pesticides and showed high initial toxicity  of 70.0% and 93.3% against M. cantiana  and E. vermiculata, respectively after three days of exposure. However, methomyl belonging to carbamate group surpassed other pesticides and gave 100.0% mortality after seven and 12 days for the two land snails, M.  cantiana and E. vermiculata, respectively. On the other hand, chlorpyrifos-ethyl exhibited the lowest mortality percentages against the tested land snails. Obviously, methomyl proved to be the most effective pesticides followed by deltamethrin, bensultap, lambda-cyhalothrin, diazonixy then chlorpyrifos-ethyl against the two land snails. Moreover, the brown garden snail, E. vermiculata showed more sensitivity to the tested pesticides especially methomyl and deltamethrin than the clover snail, M. cantiana.

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First record for the slug parasitic nematode, Phasmarhabditis hermaphrodita (Schneider) in Egypt.

, Marwa, A. M.Genena ,  Fatma, A. M. Mostafa, Fouly, A. H. and Yousef, A.A.

Agric. Zoology Dept., Fac. Agric., Mansoura Univ., Mansoura, Egypt.

ABSTRACT

 The rhabditid nematode, Phasmarhabditis hermaphrodita was first isolated in Egypt, from different species of terrestrial gastropods found associated with various crops at Aga and Mansoura districts of Dakhalia Governorate during the year 2000/2001. Females and dauer larvae (IJs) were described and illustrated based on the light microscope. Males are not found as this species seemed to be protandrous. PCR analysis confirmed nematode identification. Egyptian isolate of P. hermaphrodita was found to be shorter and less in width than British one.  V% , a, b and c parameters showed detectable variations between two isolates with values of 54% , 17.7, 4.28, 13.7 in the Egyptian isolate, and 51%, 19.5, 7.2 and 15.8 for the British one respectively

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EFFICACY OF FOUR PESTICIDES APPLIED AGAINST THE LAND SNAIL Theba cantiana (Montagu) (Gastropoda: Helicidae) AT THREE EXPOSURE PERIODS.

A.H., Fouly.; A. A. Yousef; Fatma, A. M. Mostafa and Marwa, A. M. Genena

Department of Agricultural Zoology, Fac.of  Agric., Mansoura Univ.

ABSTRACT

   The efficacy of four pesticides bendiocarb, carbaryl, fenitrothion and methomyl against the land snail, Theba cantiana (Montagu) was evaluated under three different exposure periods. Each of the tested pesticides was applied as baits at three concentrations. Data indicated that all pesticides presented the highest snail mortality in the first day of the examination. For the time being, the mortality values showed a gradual decrease to reach the minimum level on the third and fourth day after inspection. The snail mortality percentages were directly associated with the toxicant concentration. It was also clear that methomyl proved to be the most effective material followed by fenitrothion, bendiocarb and carbaryl.

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Susceptibility of different terrestrial gastropod species to the native rhabditid nematode, Phasmarhabditis  hermaphrodita.

Genena, Marwa, A. M* and  Mohsen, Fatma, A. M.

Agric. Zoology Dept., Fac. Agric., Mansoura Univ., Mansoura, Egypt

ABSTRAC

The susceptibility of four common adult helicid land snail species; Cebaea hortensis , Eobania vermiculata , Monacha cantiana  and Theba pisana ,  and the tree slug, Lehmannia marginata to the rhabditid nematode, P. hermaphrodita was carried out in vivo after one, two and three weeks of exposure to constant inoculum nematode level (3000 IJs/ cup). The screened snails and slugs showed remarkable reaction to nematode infection with different degrees. After four weeks of exposure the slug, L. marginata  proved to be the highest susceptible one to P. hermaphrodita with value of 100% followed by the clover land snail, M. cantiana and the white land snail, T. pisana with values of 76.6 and 63.3%, respectively after four weeks of exposure. However, E. vermiculata and C. hortensis gave the least mortality percentages with values of 56.7% and 40.0%, respectively. Moreover, the susceptibility of three different size-classes of M. cantiana to P. hermaphrodita indicated that the small sized snails (4mm wide &1mm high), the intermediate sized snails (7mm wide &3mm high) and the big sized snails (13 mm wide & 7mm high) were found to be susceptible to the rhabditid nematode, P. hermaphrodita but in different proportions. After two weeks of exposure to 3000 IJs/cup mortality percentage reached 100.0% in small sized, followed by intermediate and the big sized snails with values amounted to 92.0 and 40.0%, respectively. On the other hand, the impact of, P. hermaphrodita against M. cantiana under three different temperature degrees revealed an inverse correlation between mortality percentages of M. cantiana and temperature degrees after one, two and three weeks of exposure to the target nematode. The capability of P. hermaphrodita to infect and kill M. cantiana has significantly increased as the temperature declined from 30°C to 20°C after three weeks of exposure. Hence, the mortality percentages ranged from 63.6 to 87.0%.