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Title Isolation, identification and virulence of the local entomopathogenic nematode Heterorhabditis indica in the southern Philippines against the sugarcane white grub, Leucopholis irrorata (Chevrolat) (Coleoptera: Scarabaeidae)
Posted by Nanette Hope Sumaya
Authors Rolando Jr. Ramos , Cynthia Ann Dichusa, Sitaram Aryal, Elorde Jr. Crispolon, Neil Pep Dave Sumaya, Nanette Hope Sumaya
Publication date 2022/05/11
Journal International Journal of Tropical Insect Science
Volume 42
Pages 2739-2750
Publisher Springer Nature
Abstract Entomopathogenic nematodes (EPNs) are used as biocontrol agents of diverse insect pests. EPN diversity study was con- ducted in the southern Philippines (Cotabato province), encompassing a total of 5 municipalities with 25 Barangays (vil- lages) for the potential biocontrol of the sugarcane white grub, Leucopholis irrorata. Of the 25 soil samples collected, only 5 harbored nematodes by using the Galleria-baiting technique. Through preliminary assessment of morphological data and confirmation analysis of D2-D3 segments of the 28S rDNA, locally-isolated nematodes were identified as Heterorhabditis indica (1 isolate), Metarhabditis rainai (3 isolates) and Oscheius rugaonensis (1 isolate). Moreover, the virulence of the H. indica (KRR4) infective juveniles (IJs) isolated from sugarcane soils was assessed against the target local insect pests, L. irrorata grubs under laboratory conditions. The mean mortality (%) caused by H. indica isolate KRR4 on L. irrorata at dif- ferent dosages (10, 50, 100, 150, 200 and 300 IJs/grub) ranged from 37.5–100% after 24 h of exposure. The LD50 required to kill 50% of the L. irrorata grub population was 5.5 ± 2 IJs/grub. The virulence indicated that local H. indica isolate can be a promising control measure in curbing local insect pests (e.g. coleopterans and lepidopterans) and this may present fundamental information in the application of EPNs for scarab pest control and other soil-dwelling pests. The biocontrol potential of other recovered facultative necromenic or entomophilic nematodes in this study will be further investigated.
Index terms / Keywords Biocontrol, D2-D3 of 28S rDNA, EPN diversity, Local insect pests