The Asian catfish, Clarias batrachus of the family claridae, commonly known as
„magur‟ has high commercial importance in India. Aeromonas veronii has been
reported as an important bacterial pathogen for aquatic animals and humans.
Several reports have demonstrated the pathogenic effect of other Aeromonas
species on aquatic animal; however in farmed C. batrachus no definitive data are
available about A. veronii infection. In the present study, a virulent A. veronii
strain BLB-01was isolated from the infected C. batrachus collected from
freshwater fish farm Balabhadrapuram, East Godavari district, Andhra Pradesh,
India and its identification was confirmed by 16S rRNA amplification and
sequencing (Gen Bank accession number.MF370515). In addition two genes
encoding aerolysin (aerA), haemolysin (hlyA) were found present in the isolate
which further confirmed its potential virulence. Histologically, the infected muscle
tissue showed erythrocyte and leukocyte infiltration due to bacterial infection. In
vitro antimicrobial susceptibility test was also conducted by using effective
antibiotic drugs to guide the treatment of the disease.
Fruit borer, Helicoverpa armigera (Hubner) is a persistent pest on okra among fruit borer complex throughout India. Experiments were undertaken to investigate the persistence of spinetoram 12 SC against larval stage of H. armigera in the laboratory and to evaluate the effectiveness in the field in two seasons. The results of persistence toxicity revealed that there was continuous larval reduction up to 14
DAT under the laboratory condition in different doses of biological green insecticide spinetoram (36, 45 and 54 g a.i/ha). This emphasizes the need to reapply spinetoram 10 – 14 days after the first application (peak of biological activity) for effective control. In field experiments spinetoram 12 SC was significantly effective at 45 and 54 g a.i./ha when sprayed thrice at 15 days interval and minimized the incidence of fruit borer and increased the fruit yield.
As a result of repeated application of insecticides on brinjal most of the lepidopteron pests may have developed resistance. In general, newly developed compounds are desired not to show cross resistance with existing insecticides. With this background, field population of
L. orbonalis from brinjal which was known to be tolerant to most of the conventional
insecticides were collected and subjected to the in vivo toxicity of spinetoram 12 SC to assess whether cross resistance exists. Untreated larvae of both field and laboratory strains showed no mortality during the 48 hours of feeding. After 48 hours of feeding on
spinetoram 12 SC-treated fruits, LC50s of field larvae were 0.097, 0.45, 3.13 and 6.58 ppm for the 2nd, 3rd, 4th and 5th in stars of L. orbonalis respectively. However, in the laboratory strain these values were 0.76, 1.92, 17.37 and 49.55 ppm for 2nd, 3rd, 4th and 5th in stars of
L. orbonalis respectively. The results confirmed the greater LC50 of the laboratory strain than of the field strain.
Survival and fertility characteristics of the third instar larvae of Spodoptera litura (Fabricius), on Bt-I and Bt-II cotton hybrids during 120-150 DAS were assessed in the laboratory. Life tables and population parameters of the S.litura were constructed in an
environment with unlimited food supply and that was free of natural enemies. The results revealed that the modest rate of mortality occurred in the immature stage, especially in the
third instar. The population parameters calculated are recorded as low in Bt-II hybrids compared to Bt-I hybrids. The net reproductive rate (R0) recorded highest 447.24 on NCS- 954 Bt-I whereas lowest on RCH-134 Bt-II as 169.35 with the mean generation time (Tc) 40.01 days. Intrinsic rate of increase (rm) was ranged from 0.12- 0.18, the highest rm was recorded on Bt-I hybrids. The population doubling time (DT) was 5.39 days on RCH-134 Bt-II. The Bt-II hybrids have shown a profound impact on the growth and development of S.litura during early stages of crop, as the crop matured the Cry toxin content decreased, survival rate recorded was more in 4th and 5th instar larvae in later stages of crop.`
Before proceeding to analyze the impact of PMKSY watershed projects pertaining to Batch IV in YSR kadapa district, it would be worthwhile to have an idea of the genesis of IWMP, objectives, mode of operandi at state level, etc which forms the basis for clear understanding of the research paper. Watershed based integrated development programme is the basic means for drought mitigation and control of desertification. The concept of integrated land and water management on watershed basis through active involvement of the people which alone could improve the environment and productivity of resources was focused. As per guidelines of DPAP and DDP, micro-watershed should be the management unit and in each selected block the micro-watersheds may be classified into high, medium and low priority areas according to their vulnerability to droughts. Developmental programs stress more on restoration of ecological balance through optimum utilization of natural resources which may disturb the optimum land-man-livestock ratio.