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ThesisItem Restricted Biology of Brown Planthopper, Nilaparvata lugens (Stal) on rice(Punjab Agricultural University, Ludhiana, 2011) Gavneet KaurThe biology of Brown Planthopper (BPH), Nilaparvata lugens (Stal) was studied during 2010-2011 on rice cultivar PR114 under screen house conditions at the Department of Plant Breeding & Genetics, PAU, Ludhiana. The oviposition occurred mostly from 19:30 to 21:30 hours into the leaf sheath near the base of the plant. The mating period lasted for 56 -113 seconds and one male copulated with a maximum of three females. Fecundity-cum-fertility varied from 98.40 to 136.70 eggs during different periods of study with range of 3-17 eggs per egg mass. Pre-oviposition, oviposition, incubation, total nymphal period, post-oviposition, male longevity and female longevity varied from 1.70 to 2.70, 21.00 to 14.10, 5.13 to 7.40, 17.40 to 22.73, 2.30 to 6.70, 17.40 to 21.50, and 23.50 to 25.00 days during May 22-June 20, 2010 (mean temperature 30.01±3.65˚C, mean RH 74.80±7.92%) to September 4 - 30 (mean temperature 26.82±1.72˚C, mean RH 82.00±7.97%), respectively. BPH passed through eight overlapping generations during the period from June 12, 2010 - July 4, 2011. The sex ratio (male:female), wing form ratio (macropterous: brachypterous) and survival percentage varied from 1:1.09 to 1:2.07, 1:1.17 to 1:1.87 and 85.53 to 94.16 per cent, respectively during the three periods of study from May to September 2010. In host range studies, BPH oviposited on Lolium temulentum and Eleusine indica and the adults survived for a short period on nine other weed species and three crop plants. During, August- October, 2010, 29-38 adult brown planthoppers per ten sweep net were recorded on rice crop. In light trap BPH started appearing in the month of June, 2010 and it was found maximum in the months of September-October and afterwards its population declined rapidly.ThesisItem Restricted BEHAVIOURAL PHYSIOLOGY OF SUSCEPTIBLE AND INSECTICIDE-RESISTANT POPULATIONS OF DIAMONDBACK MOTH, Plutella xylostella (Linnaeus)(Punjab Agricultural University, Ludhiana, 2011) Anureet KaurFeeding, locomotory and reproductive behaviour of insecticide-resistant and susceptible populations of diamondback moth, Plutella xylostella (Linnaeus), a challenging insect-pest of cruciferous vegetable crops round the globe, was studied. The larvae from resistant P. xylostella population registered significantly low value of ECD (efficiency of conversion of digested food to body substance) i.e. 18.20 as compared to their susceptible counterparts (ECD = 22.59); other nutritional indices were at par. The resistant larvae travelled significantly less distance (260.68 cm/5 minutes) on treated-surface (with LC50 value of endosulfan, quinalphos, fenvalerate and spinosad) with more value of turn angle (231.16˚) than the susceptible ones which moved faster (517.23 cm/5 minutes) with less value of turn angle (100.63˚). The resistant moths exercised more of leg autotomy (10 %) in response to the insecticides as compared to the susceptible moth (2.5 %) ; fenvalerate resulted in maximum value of leg autotomy (13.35 %) followed by endosulfan (6.65 %), quinalphos (3.35 %) and spinosad (1.65 %). Both resistant and susceptible P. xylostella preferred untreated surface (in comparison to insecticide-treated surface) for egg-laying. The value of fecundity was maximum (185.0) when the pairs from resistant population mated and the minimum value of fecundity (135.3) was registered when both the males and females were from the susceptible population. Inspite of the higher fecundity by the resistant moths, their reproductive effort (fecundity × egg-size) could not register a higher value given to the smaller egg-size (0.023 mm3) as compared to the bigger eggs (egg-size = 0.035 mm3) of the susceptible ones. Ultrastructural studies also revealed reduced dimensions (0.0015 ± 0.001 mm3) of the ovarian follicles in resistant moths. The resistant moths also laid 3.4 fold more eggs on the stem-base of the host plant when compared with the susceptible moths. Higher activity of general esterases and acetylcholinesterases was also recorded for the resistant P. xylostella.ThesisItem Restricted TOXICITY OF DIFFERENT INSECTICIDES AGAINST SPOTTED BOLLWORM, Earias spp.(Punjab Agricultural University, Ludhiana, 2011) ShellyThesisItem Restricted “Pathogenic potential and metabolite production of stalk and midrib isolates of Colletotrichum falcatum Went on sugarcane(Punjab Agricultural University, 2011) Rakesh Kumar; Bipen KumarRed rot caused by Colletotrichum falcatum Went is one of the most important disease of sugarcane and frequent breakdown of varietal resistance is due to variation in the pathogen. Keeping in view, seven stalk and midrib isolates of C. falcatum were obtained from different sugar mill areas of Punjab was studied for morphological and cultural characteristics like colony diameter, colony colour, growth pattern, sporulation and conidial size and also for pathological variability. The average conidial size of seven stalk and midrib isolates varied from 26.8-35.0 X 7.6-8.0 μm and 23.0-27.0 X 5.7-7.0. Two midrib isolates namely MR-5 and MR-6 from CoJ 85 and one stalk isolate CF-06 from CoJ 85 were relatively fast growing with an average colony diameter in the range of 13.3-13.6 mm, 36.5-36.9 mm and 84.1-84.2 mm and 13.5-13.9, 38.5 and 84.9 after 3, 5 and 7 days of incubation, respectively. All the midrib isolates showed low and stalk isolates low, medium and high sporulation which ranged from 2.08 to 16.67 X 105/ 9 mm disc (low), 16.67 to 29.17 X 105/ 9 mm disc (medium) and 29.17 to 41.67 X 105/ 9 mm disc (high). On the basis of morphological characters midrib isolates produced dark type and stalk isolates produced with light and dark type colony colour. Pathogenic variability in midrib and stalk isolates of C. falcatum was studied on fourteen host differentials. On the basis of reaction expressed by seven midrib red rot isolates were grouped into five pathotypes based on their virulence. Group I designated as MR Pb-1 from CoJ 85 (Isolate MR-5 and MR-6) was highly virulent and produced intermediate reaction on 6 differentials and stalk red rot isolates were grouped into four pathotypes based on their virulence. Group I designated as CF Pb-1 from CoJ 85 (Isolate MR-5 and MR-6) was highly virulent and produced susceptible reaction on 10 differentials. However, no differences among isolates from a particular variety were observed. Stalk and midrib red rot isolates produced crude toxic metabolite capable of inducing part of the disease symptom on the host. Their toxicity was increased with increasing days, susceptibility of variety and its concentrations. In vitro selection system for ameliorating problem like susceptibility to red rot through somaclonal variation can be successfully addressed, especially in popular genotype CoJ 64 which has desirable traits in all other aspects except resistance to red rot disease. Three to four months old calli of CoJ 64 were screened in vitro against different concentrations of crude pathogen culture filtrate (PCF) 5, 10, 15, 20 and 25% v/v for two selection cycles, each of three weeks duration. Calli survived and exhibited further proliferation at 5, 10, 15 and 20% v/v PCF concentrations whereas, at higher concentration (25% v/v) survival and/ or proliferation was completely inhibited. Shoot regeneration percent was higher in calli selected on 5% PCF concentration than those selected on 10, 15 and 20% concentrations. PCF had markedly inhibits survival and multiplication of sugarcane tissues at all stages viz., survival, proliferation and shoot regeneration of callus. Effect of PCF on callus survival, proliferation and shoot regeneration was observed to directly related to its concentration in the selection medium.. The plantlets regenerated from selected calli, after two selection cycles each of three weeks duration, using varied concentrations of PCF were likely to produce red rot resistant plants