Search

Entomopathogenic nematodes (EPNs) are effective biocontrol agents against different insect pests. However, very little work has been done in Pakistan on the symbiotic bacteria associated with EPNs and their metabolites. In this laboratory study, two bacterial isolates i.e. Xenorhabdus spp. associated with EPN Steinernema glaseri (Steiner) (Steinernematidae) and Photorhabdus spp. associated with EPN Heterorhabditis bacteriophora (Poinar) (Heterorhabditidae), were evaluated against armyworm Spodoptera litura Fabricius (Lepidoptera: Noctuidae) which is a destructive lepidopterous pest. These EPNs associated bacterial isolates were applied @ 4×107 CFUs/mL against different larval instars of S. litura. At day one post-treatment, maximum larval mortality (59.40%) was exhibited by Xenorhabdus spp. against 2nd instar larvae followed by 52.80, 46.20 and 46.20% mortality of 5th, 3rd and 4th instar larvae, respectively. In case of Photorhabdus spp., maximum mortality (26.40%) was observed against 2nd instar larvae. In other bioassay, 40% suspensions of bacterial metabolites were evaluated against different larval instars of S. litura and were found significantly effective against all larval instars. Maximum average mortality (52.80%) was observed in Xenorhabdus spp. derived metabolites against 2nd instar larvae as compared to Photorhabdus spp. In both bioassays, mortality was increased along with the exposure time and reached 100% in all S. litura larval instars at fourth day posttreatment. Findings of this in-vitro study demonstrate that EPNs and their symbiotic bacterial isolates would be effective biorational control tools against S. litura. [ABSTRACT FROM AUTHOR]

A survey was carried out in five tehsils of District Sheikhupura for the assessment of guava decline. Maximum disease prevalence (100%) and disease incidence (36%) was recorded in Tehsil Sharaqpur. Samples of plant roots, shoots and soil were randomly collected for the isolation and identification of pathogens. Mean Colonization percentage of the Botryodiplodia theobromae Patouillard [Lasiodiplodia theobromae (Patouillard) Griffon and Maublanc] from 1987 tissues of 326 samples was counted to be (48.84%) maximum, followed by Fusarium oxysporum f.sp. psidii (44.10%), Phytophthora parasitica (38.10%), F. solani (35.10%) Helminthosporium spp. (15.20%) and Curvularia lunata (11.20%). Aspergillus flavus and A. niger were also isolated from the samples but mostly from twigs. Isolated fungi were multiplied and purified on PDA. Most dominating isolated fungus (B. theobromae) was evaluated for pathogenicity. Management of the B. theobromae was done under in vitro and in vivo conditions. In vitro efficacy of seven fungicides viz. carbendazim, thiophanate-methyl, alliette, acrobat MZ 75/667WP, dithan M-45 80% WP, mancozeb 80% WP and met al.axyl plus mancozeb 72% WP was evaluated against B. theobromae by poisoned food technique at different doses viz. recommended (R), 0.75R, 0.50 and 0.25R. All the employed doses of the test fungicides significantly reduced the biomass of the test fungal specie but recommended dose rate reduced more significantly. In field experiment, carbendazim was found to be more effective than other fungicides checked, in reducing the fungal infection in guava trees, suppressing the dieback and wilting with significant enhancement in vegetative growth of plants. © 2015 Friends Science Publishers [ABSTRACT FROM AUTHOR]

Keeping in view the staid health and ecological apprehensions coupled with the use of pesticides, entomopathogenic nematodes have the potential to supersede pesticides for the management of various pests. Brinjal is seriously affected by Meloidogyne incognita. Research was conducted on two important groups of nematodes, plant parasitic nematodes (RKNs) and insect parasitic nematodes (entomopathogenic nematodes). Steinernema asiaticum, S. glaseri, Heterohabditis indica and H. bacteriophora were evaluated at different time of application against M. incognita for invasion, development and reproduction of M. incognita. In a life cycle study, S. asiaticum and H. bacteriophora were proved more effective in influencing the life cycle of RKNs at all application times than S. glaseri and H. indica. However all application time of entomopathogenic nematodes (before, with and after) the application of M. incognita proved effective as compared to control. S. asiaticum and H. bacteriophora delayed penetration of nematode juveniles (J2) into roots of brinjal. © 2015 Friends Science Publishers [ABSTRACT FROM AUTHOR]