Evaluation of two native entomopathogenic nematodes against Odontotermes obesus (Rambur) (Isoptera: Termitidae) and Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae)

Background Entomopathogenic nematodes (EPNs) are one of the widely studied biological control agents. The present study was conducted to evaluate the efficacy of two EPNs species, Heterorhabditis bacteriophora (Poinar) (Rhabditida: Heterorhabditidae) and Steinernema aciari (Qui, Yan, Zhou, Nguyen and Pang) (Rhabditida: Steinernematidae), isolated locally from soils of Majuli river island, Assam, India against two important subterrenean pests; Odontotermes obesus (Rambur) (Isoptera: Termitidae) and Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) under laboratory conditions. Results In case of O. obesus, mortality percent was recorded by H. bacteriophora after 72 h. at 300 IJs/termite and by S. aciari at 250 and 300 IJs/termite after 96 h. The lowest LD50 and LT50 values obtained for H. bacteriophora were 13.054 IJs/termite and 26.639 h., respectively, while those of S. aciari were 42.040 IJs/termite and 31.761 h., respectively. With respect to A. ipsilon, H. bacteriophora registered a highest mortality rate at 300 IJs/larvae after 144 h. S. aciari showed 100 percent mortality at 300 IJs/larva after 168 h. The lowest values of LD50 and LT50 for H. bacteriophora were 35.711 IJs/larva and 83.050 h., respectively. The lowest values of LD50 and LT50 for S. aciari were 71.192 IJs/larvae and 97.921 h., respectively. Overall, H. bacteriophora displayed more virulence toward O. obesus and A. ipsilon than S. aciari. Conclusion Both native EPNs were found effective against O. obesus and A. ipsilon. However, H. bacteriophora was more virulent toward O. obesus and A. ipsilon than S. aciari under the laboratory conditions.

Termite Occurrence And Damage Assessment In Urban Trees From Different Parks Of Lahore, Punjab, Pakistan

Termite infestation is one of the fundamental problems associated with the loss of urban trees and ecological services. However, no such study has been performed in Pakistan to investigate the termite occurrence and assess such damages to urban trees caused by termites. For Lahore, research and comparable data on urban tree damages are rare or missing. This study surveyed six different microhabitats, including Bagh-e-Jinnah, Canal vegetation, Model Town Park, Jallo forestry, Race-course Park, and F.C. College vegetation employing three belt transects (100×5 m) method. We geo-referenced termite infested trees to investigate the termite occurrence on living and dead standing trees, termite diversity and assess the tree damage by termites' attack. We recorded four termite species (Odontotermes obesus, Coptotermes heimi, Heterotermes indicola, and Microtermes obesi) representing two families (Rhinotermitidae and Termitidae). However, the diversity indices result revealed that O. obesus (higher termite) and C. heimi (lower termite) were dominant and key species with 46.60 and 36% of occurrence among observed trees, respectively. Kernel density function indicated that the Lahore Canal and Bagh-e-Jinnah plantation shared all four termites' infestation evenly compared to other study sites. We observed the maximum number of damaged trees by termites in canal plantations with the most damaged exotic tree species Populus euramericana along the canal green belt.Additionally, we observed significant (P < 0.05) termite-tree interactions with exotic, living, and dead standing tree species and found termite colony size positively (R = 0.985) correlated with the tree trunk diameter up to breast height DBH. The average population of termites per unit volume of deadwood log was (0.39/cm3) within all plantations-sites. In conclusion, this study provides simple, reckless, and inexpensive knowledge about the assessment of termite damage of trees, which may give a better idea in making decisions on tree selection and management in urban ecosystems.

Pseudomonas Can Prevent the Parasitic Fungus, While Keeping the Crop Fungus Unaffected, in the Gardens of Odontotermes Obesus.

Insects that farm monocultures of fungi are canonical examples of nutritional symbiosis as well as independent evolution of agriculture in non-human animals. But just like in human agriculture, these fungal crops face constant threat of invasion by weeds which, if unchecked, takes over the crop fungus. In fungus-growing termites, the crop fungus (Termitomyces) faces such challenges from the parasitic fungus Pseudoxylaria. The mechanism by which Pseudoxylaria is suppressed is not known. However, evidence suggests that some bacterial secondary symbionts can serve as defensive mutualists by preventing the growth of Pseudoxylaria. However, such secondary symbionts must possess the dual, yet contrasting, capabilities of suppressing the weedy fungus while keeping the growth of the crop fungus unaffected. This study describes the isolation, identification and culture-dependent estimation of the roles of several such putative defensive mutualists from the colonies of the wide-spread fungus-growing termite from India, Odontotermes obesus. From the 38 bacterial cultures tested, a strain of Pseudomonas showed significantly greater suppression of the weedy fungus than the crop fungus. Moreover, a 16S rRNA pan-microbiome survey, using the Nanopore platform, revealed Pseudomonas to be a part of the core microbiota of Odontotermes obesus. A meta-analysis of microbiota composition across different species of Odontotermes also confirms the wide-spread prevalence of Pseudomonas within this termite. These evidence indicate that Pseudomonas could be playing the role of defensive mutualist within Odontotermes.

Pseudomonas can prevent the parasitic fungus, while keeping the crop fungus unaffected, in the gardens of Odontotermes obesus

Insects that farm monocultures of fungi are canonical examples of nutritional symbiosis as well as independent evolution of agriculture in non-human animals. But just like in human agriculture, these fungal crops face constant threat of invasion by weeds which, if unchecked, takes over the crop fungus. In fungus-growing termites, the crop fungus (Termitomyces) faces such challenges from the parasitic fungus Pseudoxylaria. The mechanism by which Pseudoxylaria is suppressed is not known. However, evidence suggests that some bacterial secondary symbionts can serve as defensive mutualists by preventing the growth of Pseudoxylaria. However, such secondary symbionts must possess the dual, yet contrasting, capabilities of suppressing the weedy fungus while keeping the growth of the crop fungus unaffected. This study describes the isolation, identification and culture-dependent estimation of the roles of several such putative defensive mutualists from the colonies of the wide-spread fungus-growing termite from India, Odontotermes obesus. From the 38 bacterial cultures tested, a strain of Pseudomonas showed significantly greater suppression of the weedy fungus than the crop fungus. Moreover, a 16S rRNA pan-microbiome survey, using the Nanopore platform, revealed Pseudomonas to be a part of the core microbiota of Odontotermes obesus. A meta-analysis of microbiota composition across different species of Odontotermes also confirms the wide-spread prevalence of Pseudomonas within this termite. These evidence indicate that Pseudomonas could be playing the role of defensive mutualist within Odontotermes.