Search

The growth or Paecilomyces lilacinus (in buffered and unbuffered medium) in a pH range of 5-9; and its survival upon exposure to high temperatures (40-50°C for 0-10 days) was studied in Potato Dextrose Broth in vitro. P. lilacinus had the tendency to alter the initial pH (acidic or basic) towards neutrality. The fungus could grow at all pH levels. However, growth was better in unbuffered medium. P. lilacinus can survive exposure to 40°C for 10 days, 45°C for 6 days and 50°C for 24h. However, the resumption of normal growth at 28±1°C was delayed. more...

No incidence of Pasteurw spp. was recorded (except on Heterodera cajani) in field crops infected with Heterodera avenae, H. zeae, Rotylenchulus reniformis or citrus Infected with Tylenchulus semipenetrans. Grape vineyards infected with Meloidogyne javanica revealed 56 per cent incidence of Pasteuria penetrans. Ten-year-old vineyards showed maximum prevalence of the bacterium. Sugar centrifugal floatation technique was better than modified Baermann's funnel method for the recovery of Meloidogyne J2 encumbered with P. penetrans spores. Bioassay of soil samples from vineyards proved more useful than routine analysis to estimate the extent of infestation of P. penetrans. more...

The bacterial parasite, Pasteuria penetrans (ex Thorne) Sayre & Starr was tested as seed treatment against Meloidogyne javanica (Treub) Chitwood in okra-cowpea-chickpea sequence. In the first crop of okra, yield increase was not significant, but 21 per cent of the juvenile population at the end of the crop carried bacterial infection to the second crop. Yield differences became evident from the second crop of cowpea, which also left 46.5 per cent less juvenile population and the incidence of bacterium increased to 29 per cent. In the third crop of chickpea, besides 52.6 per cent increase in yield, a population reduction of 57.7 per cent was recorded, 50 per cent of which carried bacterial infection. more...

Studies on the spatial distribution and seasonal fluctuation of the bacterial parasite, Pasteuria penetrans infecting root-knot nematode, Meloidogyne javanica, were conducted in naturally infested grape vineyards. Within a vineyard, a negative correlation was evident between incidence of P. penetrans and population of M. javanica. The incidence of P. penetrans was maximum during the month of October. However, Nematode populations were more influenced by the ambient temperature. The vertical distribntion of P. penetrans was similar in 0-45cm-soil profile, while it was significantly less at 4S-60cm depths. more...

Studies on the spatial distribution and seasonal fluctuation of the bacterial parasite, Pasteuria penetrans infecting root-knot nematode, Meloidogyne javanica, were conducted in naturally infested grape vineyards. Within a vineyard, a negative correlation was evident between incidence of P. penetrans and population of M. javanica. The incidence of P. penetrans was maximum during the month of October. However, Nematode populations were more influenced by the ambient temperature. The vertical distribntion of P. penetrans was similar in 0-45cm-soil profile, while it was significantly less at 4S-60cm depths. more...

Five indigenous isolates of entomopathogenic nematodes (Steinernema abbasi, S. pakistanense, Steinernema sp. and two isolates of Heterorhabditis indica) were isolated and tested in vitro for their infectivity and virulence against phorid fly, Megaselia sandhui. Use of 24-welI tissue culture plates for testing infectivity was found not suitable. Sand barrier method revealed that only H. indica (isolate II) was promising in causing significant mortality of larvae of M. sandhui at nematode inoculum levels of 300 IJs and above per five larvae. more...

Indigenous strains of Heterorhabditis indica, Steinernema asiaticum and S, siamkayai caused 100% mortality in Pieris brassicae (after 48h) and Agrotis ipsilon (after 24h), whereas it was 80, 10 and 40%, respectively in Helicoverpa armigera (after 48 h) in vitro. On Galleria mellonella, mortality by H. indica was 100% at 30°C, 6.6% at 25°C and 33.3% at 20°C after 48h, and It increased to 100% only after 120h of exposure. IJs from insects killed at 25°C could be recovered only after transferring to 20°C. Average yield of Us at 30, 25 and 20°C was 1.02x105, 1.28x105 and 1.51x105 per insect larva, respectively. S. asiaticum resulted in 93.3% mortality at 25° and 30°, and 86.6% mortality at 20°C after 120h. Though emergence of IJs was delayed by 4 days at 30° and 20°C, the 1J yield per larva was not affected. S. siamkayai caused 100% mortality after 72h at all temperatures. In laboratory bioassays, both the Steinernema species revealed ambushing, whereas H. indica exhibited cruising behaviour. more...

The inability of most EPN isolates to withstand UV rays in solar radiation is one of the major impediments for their use against foliar insect pests. To overcome this, four chemicals viz., PABA (para amino benzoic acid), Congo red, zinc oxide and titanium dioxide were tested at four concentrations (0.5, 0.25, 0.1 and 0.05%) to identify a suitable UV protectant and to standardize its concentration for use of indigenous isolates of Heterorhabditis bacteriophora and two isolates (Janti and RB-5) of Steinernema species. Nematode suspensions (1000 IJs/ml) treated with the above chemicals at different concentrations were exposed to UV radiation in a laminar flow bench for 30 and 60 min. PABA and Congo red provided nearly absolute protection from UV radiation in all the three EPN isolates. Zinc oxide was not effective (70-90% mortality in exposed IJs). Titanium dioxide protected H. bacteriophora completely at 0.5% concentration only, whereas in Steinernema Janti isolate protection was only 76% and in RB-5 isolate 40% IJs were alive even at 0.5% cone. The IJs exposed to PABA and Congo red remained infective to Galleria mellonella larvae whereas titanium dioxide hampered the infectivity. PABA and Congo red at 0.25%, and zinc oxide and titanium dioxide at 1% were not phytotoxic to mungbean. The effect of UV protectants was not nematode density-dependent, since they were equally effective at nematode populations of 1000, 2000 or 4000 IJs per ml. more...