Tolerances of hybridized entomopathogenic nematode Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae) strains to heat and desiccation

Abstract

Heat and desiccation are two major problems of entomopathogenic nematodes (EPNs) for outdoor applications. The factors decrease their survival and effectivity in the field. Thus, the success ratio drops dramatically especially in hot and drought prone regions. Hybridization of EPNs is a way to overcome these major stress problems. In the present study, heat and desiccation tolerances of ten hybrid strains, which were hybridized from six domestic strains isolated from different climatic regions in Turkey, were determined. The heat tolerance experiments were performed at 32, 34, 36, 38, 40 and 42 °C and desiccation tolerance experiments were performed at PolyEthylene Glycol (PEG) concentrations of 10, 20, 30, 40, 50, 60, 70 and 80 %. The results of the tolerance experiments are shown as mean temperature tolerated by 50% of the population (MT) and mean temperature tolerated by 10% (MT) of the strains for heat testing, and as Lethal Concentration (LC and LC) for the desiccation test. For the heat tolerance experiments, the results showed that hybrid strains had slightly higher heat tolerance levels than their parents. In the desiccation experiments, it was determined that most of the hybrid strains had greater tolerances than their parents. The outcome of the study was promising for conducting further research and trials.

Keywords

• Heat, desiccation, hybrid, tolerance, Heterorhabditis bacteriophora

Hibrit entomopatojen nematod Heterorhabditis bacteriophora ırklarının yüksek sıcaklık ve su kaybına olan toleransları

Öz

Yüksek sıcaklık ve su kaybı, entomopatojen nematodların (EPN) açık alan uygulamalarındaki en büyük iki olumsuz faktördür. Bu faktörler, arazideki etkinliği ve hayatta kalma oranını düşürmekte ve bu nedenle özellikle sıcak bölgelerde zararlılara karşı başarı oranı ciddi oranda azalmaktadır. EPN’lerin hibridizasyonu, bu iki stres faktörünün önüne geçilmesinde önemli bir yöntemdir. Bu çalışmada, Türkiye’nin değişik coğrafik bölgelerinden izole edilen 6 farklı yerli ırktan hibritlenmiş 10 farklı hibrid ırkın yüksek sıcaklık ve su kaybına olan toleransları belirlenmiştir. Yüksek sıcaklık denemeleri 32, 34, 36, 38, 40 ve 42 ºC’lerde gerçekleştirilirken, su kaybı denemeleri PolyEthylene Glycol (PEG) adlı desikatörün % 10, 20, 30, 40, 50, 60, 70 ve 80 konsantrasyonlarında gerçekleştirilmiştir. Denemelerin sonuçları yüksek sıcaklık için popülasyonun % 50’sinin hayatta kalabildiği ortalama sıcaklık (MT) ve % 10’unun hayatta kalabildiği ortalama sıcaklık (MT) olarak belirtilmişken, su kaybı için lethal konsantrasyon (LC ve LC) olarak belirtilmiştir. Yüksek sıcaklık denemesinde hibrit ırkların sıcaklığa ebeveynlerinin biraz üzerinde tolerans gösterebildiği saptanırken, su kaybı denemesinde hibrit ırkların hemen hepsinin su kaybına ebeveynlerinden daha iyi tolerans gösterdiği belirlenmiştir. Bu çalışmada elde edilen sonuçlar, bu konuda yapılacak gelecek çalışmalar için ümit verici olarak görülmektedir.

Anahtar Kelimeler

• Yüksek sıcaklık, su kaybı, hibrit, tolerans, Heterorhabditis bacteriophora

Kaynakça

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