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Molecular Identification of Entomopathogenic Nematode Isolates from the Philippines and their Biological Control Potential Against Lepidopteran Pests of Corn

Barbara L. Caoili
Barbara L. Caoili
, 
Romnick A. Latina
Romnick A. Latina
, 
Regina Faye C. Sandoval
Regina Faye C. Sandoval
 and 
Joey I. Orajay
Joey I. Orajay
   | Jun 03, 2018
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Article Category: research-article
Published Online: Jun 03, 2018
Page range: 99 - 110
DOI: https://doi.org/10.21307/jofnem-2018-024
Keywords
© 2018 Barbara L. Caoili et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Fig. 1

The Philippine map showing the sampling sites for entomopathogenic nematodes. The occurrence and distribution of Heterorhabditis indica (Δ), Steinernema abbasi (■), Steinernema minutum (●), and Steinernema tami (▢). Collection sites where no entomopathogenic nematodes (x) was isolated were also indicated. The figure was created using “maps” (Minka and Deckmyn, 2017) and “GIS tools” (Brunsdon and Chen, 2014) libraries in R software.
The Philippine map showing the sampling sites for entomopathogenic nematodes. The occurrence and distribution of Heterorhabditis indica (Δ), Steinernema abbasi (■), Steinernema minutum (●), and Steinernema tami (▢). Collection sites where no entomopathogenic nematodes (x) was isolated were also indicated. The figure was created using “maps” (Minka and Deckmyn, 2017) and “GIS tools” (Brunsdon and Chen, 2014) libraries in R software.

Fig. 2

Mean percentage mortality of Helicoverpa armigera, Ostrinia furnacalis, and Spodoptera litura 48 hr post infection exposed to 200 IJ per larva of the Philippine entomopathogenic nematode isolates namely, Heterorhabditis indica PBCB (Hi PBCB), Steinernema abbasi MBLB (Sa MBLB), Steinernema minutum (Sm ASPL3, Sm CCL4, Sm PIB2 and Sm SRTSB3), and Steinernema tami PKSC1 (St PKSC1). Different letters for mean percentage mortality show significant difference between the EPN isolates within the insect species after two-way ANOVA followed by Tukey’s multiple comparison test (alpha = 0.05).
Mean percentage mortality of Helicoverpa armigera, Ostrinia furnacalis, and Spodoptera litura 48 hr post infection exposed to 200 IJ per larva of the Philippine entomopathogenic nematode isolates namely, Heterorhabditis indica PBCB (Hi PBCB), Steinernema abbasi MBLB (Sa MBLB), Steinernema minutum (Sm ASPL3, Sm CCL4, Sm PIB2 and Sm SRTSB3), and Steinernema tami PKSC1 (St PKSC1). Different letters for mean percentage mortality show significant difference between the EPN isolates within the insect species after two-way ANOVA followed by Tukey’s multiple comparison test (alpha = 0.05).

Species identification of the entomopathogenic nematode (EPN) populations in the Philippines based on molecular data.

Collection site (sample code) Associated crop Soil type/pH/% OM Detected EPN species % Nucleotide identity/GenBank Acc. No. of significant hit Assigned GenBank acc. nos. (for this paper)
Atisan, San Pablo, Laguna (ASPL3) Bignay (Antidesma bunius) Loam/6.1/4.40 Steinernema minutum 98/GU647156.1 (Maneesakorn et al., 2010) KY807711
Curba, Calauan, Laguna (CCL4) Cassava (Manihot esculenta) Clay Loam/6.4/2.37 S. minutum 98/GU647156.1 (Maneesakorn et al., 2010) KY807712
Mataas na Bayan, Lemery, Batangas (MBLB) Sugarcane (Saccharum officinarum) Sandy Loam/4.4/0.99 Steinernema abbasi (=thermophilum) 99/AY248749.1 (Nguyen and Byron, 2003) KY807713
Puting Bato, Calaca, Batangas (PBCB) Mango (Mangifera indica) Sandy Loam/6.6/4.55 Heterorhabditis indica 100/GQ377411.1 (Khatri-Chhetri et al., 2010) KY807714
Poblacion, Impasug-ong, Bukidnon (PIB2) Sugarcane (S. officinarum) Clay/5.2/3.79 S. minutum 98/GU647156.1 (Maneesakorn et al., 2010) KY807715
Paraiso, Koronadal City, S. Cotabato (PKSC1) Sugarcane (S. officinarum) Sandy Loam/5.0/1.04 Steinernema tami 98/AY171280.1 (Spiridonov et al., 2004) KY807716
San Rafael, Santo Tomas, Batangas (SRSTB3) Corn (Zea mays) Silty Clay Loam/5.0/2.43 S. minutum 98/GU647156.1 (Maneesakorn et al., 2010) KY807717

Mean percentage penetration rate of Heterorhabditis indica PBCB and Steinernema abbasi MBLB in Helicoverpa armigera, Ostrinia furnacalis, and Spodoptera litura larvae at 48 hr post inoculation.

Mean penetration rate (%) ± SE
EPN isolate H. armigera O. furnacalis S. litura
Hi PBCB 14.35 ± 0.49a 14.25 ± 0.35a 18.18 ± 1.35a
Sa MBLB 28.15 ± 2.51b 14.54 ± 0.41a 23.15 ± 0.29b
Control 0.00c 0.00b 0.00c

Median lethal time (LT50) estimates of Philippine Heterorhabditis indica PBCB (HiPBCB) and Steinernema abbasi MBLB (SaMBLB) isolates on lepidopterous pests of corn Helicoverpa armigera, Ostrinia furnacalis, Spodoptera litura. Lethal times were estimated using 200 IJ/larvae within 48 hr post infection.

95% Fiducial limit
EPN isolate Insect species LT50 (h) Lower Upper Slope ± SE χ 2 df
Hi PBCB H. armigera 30.962c 29.835 32.015 6.947 ±0.954 0.224 5
O. furnacalis 21.901a 21.273 22.440 12.797 ±1.059 3.684 5
S. litura 24.309b 23.567 24.994 8.763 ±0.826 0.802 5
Sa MBLB H. armigera 32.264c 29.929 35.835 3.892 ±0.514 1.423 4
O. furnacalis 24.177a 23.322 24.960 10.282 ±0.882 0.253 3
S. litura 26.586b 25.847 27.312 12.036 ±0.938 2.119 3

Median lethal concentration (LC50) estimates of the Philippine Heterorhabditis indica PBCB (Hi PBCB) and Steinernema abbasi MBLB (Sa MBLB) isolates to lepidopterous pests of corn, Helicoverpa armigera, Ostrinia furnacalis, Spodoptera litura.

95% Fiducial limit
EPN isolate Insect species LC50 (IJs/larva) Lower Upper Slope ± SE χ 2 df
Hi PBCB H. armigera 19.98b 16.63 24.32 1.58 ±0.16 1.87 3
O. furnacalis 10.52a 8.82 12.74 1.65 ±0.16 1.65 3
S. litura 8.89a 6.98 10.98 2.857 ±0.24 3.46 3
Sa MBLB H. armigera 22.57b 18.80 27.61 1.60 ±0.16 0.98 3
O. furnacalis 10.98a 8.25 15.21 1.88 ±0. 17 3.60 3
S. litura 17.08ab 12.27 24.07 2.03 ±0.17 3.77 3
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