دراسة مخبرية لتأثير درجات الحرارة في فاعلية بعض عزلات النيماتودا الممرضة للحشرات من الجنسين Heterorhabditis و Steinernema المستخلصة من ترب بعض بساتين الفاكهة في ريف دمشق

الملخص EN

Study was conducted to verify the pathogenic efficacy of six nematodes strains isolated from soil of some fields of Damascus Countryside using the concentration of 250 individual / ml on the last stage wax worm, Galleria mellonella larvae under different temperatures (15, 20, 25 and 30°C), where three isolates, belong to the genus Heterorhabditis and three isolates belong to Steinernema.

The assessment of effectiveness was calculated depending on the knowledge of the death and reproduction rate of the nematodes under different temperature levels.

Results showed that the temperature 25°C is optimal for all isolates used in terms of the death rate, as results showed that the isolates of the genus Steinernema more adapted to low temperatures compared to Heteerorhabditis isolates, where these isolates had the highest percentage of death at 15°C, while the Heterorhabdditis isolates achieved the highest rate of death when the temperature was 30°C.

The time required to kill 50% of the wax worm larvae at different temperatures was calculated, it decreased with increasing temperature for each of the isolates.

The results showed that the shortest life cycle was at the temperature 25°C, whereas at 1515°C Steinernema isolates were the fastest in the life cycle, while the life cycle of the Heterorhabditis isolates was slow and long at this temperature.

Where infectious individuals exited after long of infection, when the temperature was 30°C Heterorhabditis isolates were the fastest in life cycle.

The reproduction rate of the isollates were calculated under different temperatures and the results showed that Steinernema isolates gave the highest density of the infectious stage at the temperature 15°C, also Heterorhabditis isolates had achieved the highest concentration of the infectious stage at 30°C whereas infectious individuals of Steinernema isolate RST did not exit at this temperature.

And the few infectious individuals that emerged from the isolates RM and RTA of the genus Steinernema at the temperature 30°C were vitality weak