Heterodera latipons (Scholz and Sikora, 2004)

Tatli, Yiğit Ali, Bozbuğa, Refik, Özer, Göksel, Mokrini, Fouad, Lahlali, Rachid, Dababat, Abdelfattah & İmren, Mustafa, 2021, Effects of temperature and duration of storage on the hatching behaviour of Heterodera latipons (Nematoda: Heteroderidae), Turkish Journal of Zoology 45 (1), pp. 1-10 : 3-7

H. latipons populations were determined in the wheatgrowing areas of 4 sampled sites in Adana, Hatay,

Gaziantep, and Kilis provinces, which were identified to be historically infested with H. latipons ( Table 1). The average number of cysts per g of soil was estimated to determine the density of H. latipons . The highest density of nematodes was 0.82 cyst g –1 of soil, obtained in samples from Kilis Province, while the lowest cyst density (0.23 cyst g –1 of soil) was recorded in samples from Hatay Province.

3.2. Molecular identification

The amplification product using the TW81 and AB28 primers for the cyst populations were fragments of approximately 1040 bp. BLAST analysis of the ITS sequences confirmed the morphological identification of the populations. All sequences of the populations from this study were deposited in GenBank under the accession numbers listed in Table 1, and compared based on the ITS loci of the Heterodera populations, as shown in Figure 1.

3.3. Hatching of the H. latipons second-stage juveniles at different temperatures

The hatching rate of the J2s of the eastern Mediterranean populations was significantly (P ≤ 0.05) different than that of the south-eastern populations, according to the incubation temperature for 12 weeks. In general, limited

priorincubations at 10 and 15 °C for 12 weeks, on the cumulative

hatching of H. latipons populations. J2s emerged from the incubated cysts of the populationsat 5 and 20 °C. However, hatching increased gradually and reached a maximum level at 10 and 15 °C for 12 weeks. The highest hatching from the incubated cysts for all of the tested populations occurred at a temperature of 10 °C, while the lowest emergence of J2s occurred at a temperature of 5 °C. The total cumulative percentages of hatching at 10 °C ranged from 74.8% to 62.4% for the eastern Mediterranean and the south-eastern populations, respectively. The second highest hatching appeared at 15 °C, and ranged from 58.8% to 48.4% for the eastern Mediterranean and the south-eastern populations, respectively. Moreover, they were statistically significantly different from those observed at 20 and 5 °C, which did not exceed 37%.

At 20 °C, the J2s of the 2 populations were initiated to hatch at various times.For all of the eastern Mediterranean populations, the J2s began to hatch 2 weeks after the beginning of the experiment, while the J2s of the south-eastern populations only started to emerge after 4 weeks ( Table 2, Figure 2 ). Despite the early onset of hatching in the J2s of the eastern Mediterranean populations, hatchability at 20 °C was the lowest among all of the populations when compared to the other temperatures (10 and 15 °C). After 12 weeks, the cumulative hatching of J2s was considerably lower (30.8%) in the south-eastern populations than those of the eastern Mediterranean populations (36.2%).

At 15 °C, the J2s of all of the H. latipons populations hatched from cysts at different times, and their cumulative hatching rate was higher than those noticed at 5 and 20 °C. Hatching of the J2s in the eastern Mediterranean populations began 3 weeks after the start of the experiment, while J2 hatching in the south-eastern populations started at 4 weeks after the beginning of the experiment. The final cumulative hatching rate of the J2s in the eastern Mediterranean populations was 58.8%, while the incidence of emergence of the J2s in the south-eastern populations was 48.8% after 12 weeks ( Table 2, Figure 2 ).

All of the populations tested showed higher cumulative performance (74.8%) at 10 °C than at the other temperatures (P ≤ 0.05) after 12 weeks. Hatching of the J2s in the eastern Mediterranean populations began 3 weeks after the beginning of the experiment, while J2 emergence in the south-eastern populations began 4 weeks after the start of the experiment. The final cumulative hatching rate of J2s in the eastern Mediterranean populations was 74.8%, while the incidence of J2 emergence in the south-eastern populations was 62.4% after 12 weeks.

The number of hatched J2s at 5 °C was lower than those at 10, 15, and 20 °C (P ≤ 0.05) for all of the tested populations. In the south-eastern populations, the hatching of J2s began 7 weeks after the start of the experiment, while J2 hatching in the eastern Mediterranean region populations started only 6 weeks after the beginning of the experiment. The final cumulative hatching rate of the J2s in the eastern Mediterranean populations was 29.8%, while the incidence of emergence of the J2s in the south-eastern populations was 22.3% after 12 weeks.

3.4. Hatching of H. latipons second-stage juveniles following storage temperature

Percentages of the cumulative hatched J2s of the eastern Mediterranean and the south-eastern populations were recorded weekly at 15 and 10 °C for 12 weeks, following prior exposure to storagetemperatures 5 and 20 °C for 8 weeks. These treatments were compared to the control treatments, which were incubated directly at 10 and 15 °C, without an initial storage period. J2s that were incubated at 15 and 10 °C following prior exposure to storage periods showed higher hatching in all of the populations after 12 weeks than in the previous hatching experiment at the other temperatures.

Variations in the J2s hatching patterns between the eastern Mediterranean and south-eastern populations were observed after 8 weeks of cyst storage at 5 and 20 °C, followed by incubational periods at 10 and 15 °C for 12 weeks. The storage period at 5 °C, followed by incubation at 10 °C, delayed hatching in the eastern Mediterranean and south-eastern populations. Hatching of the J2s in the populations tested at 10 °C occurred 3 weeks after a storage period of 8 weeks at 5 °C, while hatching of the J2sin the eastern Mediterranean and south-eastern populations for at 15 °C occurred immediately after the 8-weekstorage period at 5 °C. The final cumulative hatching for the eastern Mediterranean populations ranged between 80.2 and 63.8%, for 10 and 15°C, respectively. Moreover, the overall incidence of emergence of the J2s in the south-eastern populations was between 71.4 and 60.8% at 10 and 15°C, respectively ( Table 3, Figure 3 ).

incubations at 10 and 15 °C for 12 weeks, on the cumulative

hatching of H. latipons populations.

An increase in J2s hatching was observed in the eastern Mediterranean and south-eastern populations when stored at 20 °C for 8 weeks, and then incubated at 10 and 15 °C. Hatching of the J2s in the eastern Mediterranean populations after 8 weeks of prior exposure of the cysts to 20 °C for 10 and 15 °C started in the first week, at a hatching rate that ranged between 74.2% and 64%, respectively. Furthermore, J2s in south-eastern population hatched in the first week after prior exposure to 20 °C for 8 weeks and showed final cumulative hatching of 66.4%–60.8% ( Table 4, Figure 4 ).

Figures

Figure 1.Neighbour-joining treeconstructedbased onthe ITS sequencealignment of the H. latipons populations from this study and corresponding populations representing species fromGenBank.Numbers on the branches represent bootstrap values obtained from 1000 bootstrap replications.

Figure 2. Effect of various temperatures on the emergence of J2s (J2s) of H. latiponspopulations. Cumulative percentages of hatched J2s followed by the same letter were not significantly different according to the Tukey HSD test at P ≤ 0.05. Vertical bars indicate standard deviation of the means.

Figure 3. Effect of storage temperature at 5 °C, for 8 prior incubations at 10 and 15 °C for 12 weeks, on the cumulative hatching of H. latipons populations. Cumulative percentages of hatched populations. Vertical bars indicate the standard deviation of the means.

Figure 4. Effect of storage temperature at 20 °C, for 8 prior incubations at 10 and 15 °C for 12 weeks, on the cumulative hatching of H. latipons populations. Cumulative percentages of hatched populations. Vertical bars indicate the standard deviation of the means.