http://www.erepo.iihr.ernet.in/handle/123456789/497 2013-05-16T21:33:25Z http://www.erepo.iihr.ernet.in/handle/123456789/504 Title: Ecology and management of stone weevil Authors: D K, Nagaraju Abstract: Mango stone weevil, (MSW) Sternochetus mangiferae (Fabricius) (Coleoptera: Curculionidae) is an important monophagous pest of mango, its ecology and ethology have escaped the attention of entomologists, but its effects as a pest of mango fruit is highly pronounced affecting yield and exports. In order to understand the insect better, for better management, there is a need to follow the insect, into its niches like seed and bark in an intensive manner. Hence, the present study was conducted at the laboratory and fields of Indian Institute of Horticultural Research (IIHR), Bangalore (12o58’N; 77o35’E) during 2001-2005. The different linear and non-linear models employed could explain the variability in infestation at harvest due to the infestation in fallen fruits to the extent of 57 to 83% in different varieties. Further, per cent infestation at harvest was predicted using polynomial model order 2 equation in Alphonso and Banganpalli, and polynomial model order 3 in Totapuri. An adult infested by Beauveria bassiana (Balsamo) Vuillemin was found. The natural occurrence was < 1%, but under laboratory conditions, the fungus gave 100% mortality of adults in 2-7 days when sprayed at 1.3 x 109 spores per ml concentration. Carbaryl, acephate and deltamethrin with 3.33, 6.67 and 8.15% infestation, respectively were effective. Ethofenprox with 14.82% infestation gave intermediate control. Fish oil rosin soap and azadirachtin were not effective. The study clearly brought out for the first time that infestation begins on fruits of 2-4 cm diameter. This is the time to initiate management interventions. The discovery that majority of the adults eventually rest in junctions of main trunk and primary branches augur well to target spot application of insecticides on the main trunk prior to fruiting, thus obviating full canopy sprays. The fact that older trees harboured more MSW is also crucial in being vigilant to MSW infestation. This is environment friendly cost effective and time saving, as trunk spot application requires only 1/5th of spray liquid. The study showed that prediction of weevil infestation in a variety is possible. As stretches of mango of one variety are common in India, this will be useful in forecast and surveillance. The efficacy of B. bassiana demonstrated that the eco-friendly IPM is a potential future venture. 2005-01-01T00:00:00Z http://www.erepo.iihr.ernet.in/handle/123456789/503 Title: Population dynamics, biology and management of Amrasca splendens Ghauri Authors: S, Rudresh Abstract: The present investigations were made during 2003-04 on the different aspect of Amrasca splendens Ghauri at IIHR namely, seasonal incidence, biology, extent of damage, management of A .splendens and response of leaf hopper to Alphonso, Banganapalli and Totapuri varieties, All the aspects were summarized below. Seasonal incidence of A. splendens indicated that three population peaks were observed, with the second peak was observed during third week of April (23.20 mean leafhoppers per shoot). The first peak during third week of June (11.05 mean leafhoppers per shoot) and third peak was during last week of November (0.29 mean leafhoppers per shoot). Incidence of A. splendens was found on all the commercial varieties studied namely, Alphonso, Banganapalli and Totapuri from May 2005. On these varieties the incidence gradually increased from February to March and reached its peak during April, from then the population started declining and reached a minimum during July to October, July to March and May to January, in Banganapalli, Totapuri and Alphonso, respectively. The Incidence of A. splendens had showed positive significant correlation with maximum temperature(r=0.38) minimum temp. (r=0.36) and flushing(r= 0.67). Tender leaves were found to have positive effect. Further, the studied showed that co-occurrence of factors like maximum temperature at third week prior to leafhopper incidence and flushing at one week prior to leafhopper incidence explained the leafhopper density up to 65 per cent. Relative humidity and wind speed were not found to have any effect. Studies on the biology of A.splendens on mango were conducted under laboratory conditions, during April 2004. Previposition, oviposition, and post oviposition periods lasted for 8 to 10, 10 to 12 and 4 to 6 days, respectively. The total fecundity based a nymphal emergence ranged from 15 to 26 eggs per female. Eggs were slightly oval and transparent and were laid in the midrib, vienlets and occasionally in leaf lamina. Oviposition per days varied from 1 to 4 during peak season for per female. It took 4 to 5 days for hatching. The nymphs passed through five instars and they lasted for 0.69, 1.25, 1.94 and 2.63 days, respectively. During the course of the study three predators namely Isyndus heros Fab. And Mantis religiosa Lab., were found attacking the different stages of the leafhopper. However these were of no major consequence. The female adults caused the major damage by ovipositing in midrib towards anterior region of tender leaf, which resulted in blockage of phloem tube due to which, drying of leaf apex backward was observed. However in majority of damaged leaves the dried tip just break off leaving a typical “tip cut” symptom. After emergence nymphs cluster on the lower side of the tender leaves and suck sap from midrib and vienlets. Under server infestations, the leaves of sprouting shoots withered and ultimately fell down. The oviposition in the midrib caused anatomical changes in the leaf midrib and as well as in lateral veins of the leaves. The healthy midrib stained in toluidine blue mercuric bromophenol blue and periodic acid Schiff’s reagent has indicated the presence of vascular bundles and other related structures, where as in infested tissue the staining was either blank or very lightly indicated the degeneration of tissue or the presence of chitinaceous materials in the midrib (left out material of chorion). Further, it could be clearly seen that there was an opening in the midrib to indicate the escape of nuymphs by rupturing midrib. Studies were conducted on the management of A.splendens during April 2005. The botanicals namely viz., Pongamia soap 10 g/l, Neem soap 10 g/l, Neemazal 1.5ml/l, Neemark+ 1.5ml/l, Neem oil 10ml/l, NSKE 4% were used for the study. Endosulfan 2ml/l was used to compare the efficacy of botanicals. The results showed that neem oil 10ml/l and NSKE 4% giving 100 per cent control of the leafhoppers. 2004-01-01T00:00:00Z http://www.erepo.iihr.ernet.in/handle/123456789/502 Title: Bio-ecology, population dynamics, pest-predator-ant interactions with reference to the aphid, Aphis punicae Passerini in pomegranate ecosystem Authors: K, Sreedevi Abstract: Studies on "Bio-ecology, population dynamics and prey-predator-ant interaction with special reference to pomegranate aphid, Aphis punicae Passerini" were carried out during 2000-2003 at the Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessaraghatta Lake - PO, Bangalore (12˚58'N; 77˚35'E), India. The major conclusion drawn from the present study were - The aphid, A. punicae has 4 nymphal instars of duration 1 – 1.5 days each. Thus total nymphal duration was found to be 4 – 5 days and adult longevity ranged from 2 – 8 days. Total life cycle was observed to range from 6 to 13 days. The seasonal incidence of A. punicae has shown two peak periods. A major peak during January – February and a minor one during July – June were observed. Predators were found in abundance during both the peaks and showed numerical response to its prey, A. punicae The fungus, E. aphidis was found to occur in epizootic form on aphids. The ants were not associated with aphid during January – March, however, they were found associated during July – September. The crop phenology factors that influenced aphid population the most were tender shoots, which favoured the aphid multiplication while the full matured leaves and medium to large fruits that did not favour the population build up. Predators were also negatively correlated with the full matured leaves. Ants were positively related with full matured leaves and negatively with tender shoots showing just opposite relationship with what aphids showed. Among meteorological factors, the relative humidity and minimum temperature showed negative influence on A. punicae population. However, predators were not influenced by weather parameters, once again confirming that they were prey- dependent. Ants were positively related to the wind speed and temperature. The aphid infestation had negative impact on fruit size and development. Among different predators, C. sexmaculata was found to be the most abundant species followed by Scymnus on A. punicae in pomegranate ecosystem. Prediction models were developed for A. punicae with three independent variables viz., tender shoot, relative humidity and minimum temperature. These findings can serve as a basis to develop further IPM strategy 2003-01-01T00:00:00Z http://www.erepo.iihr.ernet.in/handle/123456789/501 Title: Studies on short hole Xylosandrus crassiusculus on grapes cv. Bangalore Blue Authors: G, Keshava Reddy Abstract: The investigations on different aspects of grape shot hole borer, Xylosandrus crassiusculus (Motshulsky) (Coleoptera: Scolytidae) were carried out during 2002-03. The studies included distribution of the beetle infestation on grapes in and around Bangalore, potential of ethanol in trapping scolytid beetles, effect on growth parameters of grape vide with relation to infestation, spatial distribution of beetle damage on main trunk and management of X. crassiusculus. During the survey, two species of scolytid beetles viz., Xylosandrus crassiusculus and compactus (Eichooff) were recorded on grapes vines. Of these, the latter is new record, which has been sighted only on cuttings of Vitis vinifera. The present study revealed that Xylosandrus crassiusculus mainly preferred cv. Bangalore Blue grapes and its infestation was more in Bangalore North (Urban) area than other areas like in Bangalore rural and Kolar districts. Significant relationship was not observed between beetle infestation and number of vines in a garden or type of irrigation. However, infestation was more as the age of the vines increased. Traps with 20% ethanol were found most effective in trapping scolytid beetles. The trap catches of scolytids showed significant negative relationship with minimum temperature and wind speed. However, there was no significant correlation with other abiotic factors viz., maximum temperature, relative humidity and rainfall. The number of scolytid damaged holes on the main trunk was significantly and negatively correlated with total number of sprouts. This implied that as the infestation levels of scolytids increased on the vine trunk, the number of sprouts produced by the vines after pruning reduced. Due to the stress caused by the beetle attack on the main trunk of the vines, the flow of water and nutrients to the growing tips and leaves, after bud sprouting may have been affected. Similarly as the number of sprouts decreased with the severity of the shot hole borer infestation, the number of bunches per vine also decreased. However, within a bunch, the number of berries, which directly contributed to the weight of the bunch, was not affected. But overall productivity was affected. From the study carried out at the IIHR vineyard, it was found that if control measures are taken immediately after noticing the shot hole borer attack on the trunks by regular and close monitoring for pest attack, the growth and development of the vines and yield (No. of bunches) are not affected. Distribution of Xylosandrus crassiusculus damage holes was found to be clumped or aggregated at all height intervals on the main trunk as variance-mean ratio was more than unity. This was further confirmed by indices like negative binomial of ‘ k’ and David and Moore Index. The correlation coefficients were worked out to know whether the infestation(bored holes) at different height intervals, was related to the overall density of holes on a trunk. It was found that scolytid holes density at all height intervals was significantly and positively correlated with total number of holes on the trunk. However, the number of holes present at 0-30 cm and 60-90 cm height intervals showed highly significant ‘r’ values with total number of bored holes on the trunk. Based on these ‘r’ valued, different models were developed. The models which had higher ‘R2 values were used for predicting the total number of holes on a vine. At 0-30 cm height, power model, y=6.28 x 0.95 and 60-90 cm height power model, y= 18.780.66 would explain the reliability of variation of total number of scolytid holes of a vine up to 81% and 94%, respectively. So these models can be recommended for further sampling and prediction. Further, the predicted estimates using the above said models were not significantly different from observed values(based on ‘t’ test). Management studies showed that the efficacy of chemicals viz., dichlorvos 76 EC @ 0.228%, acephate 7SSP @ 0.225%, dichlorvos + acephate, dichlorvos+ acephate + carbendazim 50% WP @ 0.30%, Neem oil @ 1% and cypermethrin 25EC @ 0.225% were evaluated against Xylosandrus crassiusculus on grape vine trunk in the form of two swabbing at 30 days interval. Of these, dichlorvos + acephate + carbendazim , dichlorvos+ acephate and dichlorvos emerged as the most promising treatments from two trials. Accephate, neem oil and cypermethrin had moderate effect in controlling Xylosandrus crassiusculus. For low levels of infestation, especially if detected early, dichlorvos is sufficient. The swab with combination of chemicals was more efficacious, cost-effective and less hazardous, in terms of drift to non-target areas compared to sprays taken by farmers. 2003-01-01T00:00:00Z