Thumbnail Image

Theses

Browse

20182
Reset filters
Subject: Entomology × End date: 2018 × Start date: 2018 × Type: Thesis × Thesis Type: Ph.D ×
Reset filters

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    ThesisItemOpen Access
    DIVERSITY OF SPIDERS (ARANEAE) IN TEA
    (AAU, Jorhat, 2018-01) Hazarika, Somar; Bora, D.K.
    A survey was conducted to study the diversity of spiders in different tea gardens viz., conventional, organic and small grower tea gardens of Jorhat district from May, 2016 to April, 2017. The results revealed a total number of 2954 specimens of spiders collected under 16 genera, 8 families and 20 species viz., Cyrtophoracicatrosa, Nephila kuhlii, Argiope pulchella, Cyclosa mulmeinensis, Neoscona sp, Cyclosa spirifera, Cyclosa bifida, Araneus mitifica, Oxyopes sitae, Oxyopes shweta, Oxyopes sp, Rhene danieli, Phintella vittata, Telamonia dimidiata, Tetragnatha sp, Leucauge decorata, Heteropoda ventoria, Xysticus sp and Perdosa peaudoannulata. Among all the species, Castianeira furva has been recorded for the first time from this region. Species richness (R = 3.07) and evenness (E = 0.96) was recorded the highest in Deha T.E. (organic garden) and was found lowest for Saikia T.E (small grower garden) i.e., 2.51 and0.89 respectively. However, species diversity was recorded highest in conventional garden, Dhloi T.E. (H’ = 2.88). The correlation studies revealed that the spider population exhibited significant positive correlation with total rainfall (r = 0.776) and non-significant for maximum temperature, minimum temperature and evening relative humidity while, a significant negative correlation was observed with morning relative humidity (r = -0.797) and bright sunshine hour (r = -0.676). Some morphological and biochemical characters of seven selected tea clones (TV 1, TV 2, TV 7, TV 9, TV 12, TV 18, TV 23) in the Experimental Garden of Plantation crops, Assam Agricultural University, Jorhat were examined to determine their effects on common insect pests and spider population. The results showed that all the clones were susceptible to the pests, TV 23 being more susceptible compared to others (H. theivora 6.22 no/bush, O. coffeae 18.35 no/leaf, Hyposidra sp 3.43 no/bush). However, no significant difference for spider populations was found to exist amongst the clones. With respect to morphological characters, the examined clones showed significant difference for total number of branches, leaf area and trichome densities. The differences in leaf moisture contentwere also significant. Moreover, it was found that the phenol content of examined clones gradually decreased due to pest infestation and the reduction was highest in TV 23 (22.43%). The linear correlation among morphological and biochemical attributes of selected tea clones with pests showed that total no of branches and leaf area had a non significant negative correlation with H. theivora (r = - 0.664, - 0.333), O. coffeae (r = -0.277, -0.175) and Hyposidra sp (r = -0.156, -0.179) while trichome density had significant negative correlation with H. theivora (r = -0.643) O. coffeae (r = -0.475) and Hyposidra sp (r = - 0.493). However, the moisture content showed a non-significant positive correlation for H. theivora (r=0.064) but established a negative association with O. coffeae (r = -0.446) and Hyposidra sp (r = -0.370). Regarding insect pests, both the reduction in phenol content and spider population exhibited a significant positive association. A field experiment was conducted in the Experimental Garden of Plantation crops, Assam Agricultural University, Jorhat, during 2016 and 2017 to investigate the effect of pesticides on common insect pests and spider population in tea plantation. On the basis of the pooled data of two year observations recorded at 1st, 5th and 10th days after application and revealed that all the treatments showed significant differences over control. Among the treatments thiomethoxam 25% WG @ 0.01% was found to be most effective against H. theivora followed by deltamethrin 2.8 EC @ 0.02% and azadirachtin @ 0.003%, whereas spiromesifen 240 SC @ 0.2% was found to be least effective against H. theivora population. The pooled data on the efficacy of different pesticides on O. coffeae revealed that spiromesifen 240 SC @ 0.2% was most effective followed by ethion 50EC @ 0.25%, deltamethrin 2.8 EC @ 0.02% and azadirachtin @ 0.003% whereas thiomethoxam 25% WG@ 0.01% @ was found to be least effective against O. coffeae population. Among all the treatments ethion 50EC @ 0.25% was found to be most toxic on spider population followed by deltamethrin 2.8 EC @ 0.02% and B. bassiana @ 2% was found safer to spider population which was followed by azadirachtin 5 EC 0.003%.
  • Thumbnail Image
    ThesisItemOpen Access
    POPULATION MONITORING AND MANAGEMENT OF RED ANT, Dorylus orientalis WESTWOOD (HYMENOPTERA: FORMICIDAE)
    (AAU, Jorhat, 2018-01) Devi, Elangbam Bidyarani; Bhattacharyya, Badal
    Field and laboratory experiments were carried out in the farmer’s field of Jorhat and Soil Arthropod Pests Laboratory, Department of Entomology, Assam Agricultural University, Jorhat during 2015-16 and 2016-17 to study the population monitoring and ecofriendly management of red ant, D. orientalis in potato and French bean. The population of red ants were recorded under flood free and flood prone conditions in three different villages each during potato growing season and were correlated with various meteorological parameters and soil physico-chemical properties. Highest population of red ants was observed in all the flood free villages during the 1st fortnight of January, 2016 and 2017 as compared to the flood prone villages, where very negligible population of red ants was noticed. Correlation studies between D. orientalis population and various meteorological parameters during 2015-16 revealed that minimum temperature, soil temperature (morning and evening) and evaporation rate showed significantly negative correlationship whereas relative humidity (morning and evening) exhibited significant positive correlationship in case of flood free villages. However, in flood prone villages minimum temperature as well as morning soil temperature showed significant negative correlation with D. orientalis population. During 2016-17, the population of D. orientalis showed significant negative correlation with temperature (minimum and maximum), soil temperature (morning and evening) and evaporation rate but relative humidity (morning and evening) as well as bright sunshine hours had significant positive correlation with D. orientalis population. Whereas in flood prone villages, relative humidity (morning and evening) showed significant positive correlation with D. orientalis population. In case of soil physico-chemical parameters, bulk density, clay content, CEC, available N and soil microbial biomass carbon showed significant negative correlation while sand, silt content, soil organic carbon and available K2O had significant positive correlation in all the flood free villages. In flood prone villages, sand, silt and clay content, available P2O5, available K2O and CEC had showed positive correlation with D. orientalis population on the other hand, soil pH and available N showed significant positive correlation. Six different eco-friendly managment modules were evaluated against D. orientalis in potato crop. All the tested modules viz., Module-I (with only pre sowing treatment with MOC @ 150 kg/ha + wood ash @ 150 kg/ha + panchagavya @ 3%), Module-II (pre sowing treatment plus soil drenching with neem oil @ 5 ml/lit after 1st & 2nd earthing up (25 & 60 DAS), Module-III (pre sowing treatment plus soil drenching with jatropha oil @ 5 ml/lit after 1st & 2nd earthing up (25 & 60 DAS), Module-IV (pre sowing treatment plus soil drenching with pongamia oil @ 5 ml/lit after 1st & 2nd earthing up (25 & 60 DAS), Module-V (pre sowing treatment plus soil drenching with castor oil @ 5 ml/lit after 1st & 2nd earthing up (25 & 60 DAS) and Module-VI (pre sowing treatment plus soil drenching with sesamum oil @ 5 ml/lit after 1st & 2nd earthing up (25 & 60 DAS) were found to be significantly superior in suppressing red ant infestation as compared to the untreated control. Out of all modules, Module-II was found to be significantly superior and recorded the lowest tuber damage on weight (8.65%) and number (10.70%) basis which was at par with the Recommended package of practices (RPP) (malathion 5% dust @ 40 kg/ha + mustard oil cake @ 150 kg/ha in the soil after 1st & 2nd earthing up) which registered 8.18 and 10.20 per cent tuber damage respectively. The same module also registered highest tuber yield (119.37 q/ha) which was at par with the RPP (120.12 q/ha). The maximum benefit cost ratio (1.43) was recorded in RPP followed by Module-II (1.35) and Module-VI (1.26). Similar trend was also observed when six different eco-friendly managment modules were tested against, D. orientalis in French bean crop. Module-I comprised of only pre sowing treatments (application of MOC @ 150 kg/ha + wood ash @ 150 kg/ha + panchagavya @ 3%) and was common for rest of the modules (M-II to VI). Experimental findings revealed that all the tested modules viz., Module-I, Module-II (soil drenching with neem oil @ 5 ml/lit after 1st weeding up), Module-III (soil drenching with jatropha oil @ 5 ml/lit after 1st weeding up), Module-IV (soil drenching with pongamia oil @ 5 ml/lit after 1st weeding up), Module-V (soil drenching with castor oil @ 5 ml/lit after 1st weeding up) and Module-VI (soil drenching with sesamum oil @ 5 ml/lit after 1st weeding up) were found to be significantly superior in reducing red ant infestation as compared to the untreated control. Out of all the modules tested, Module-II was found to be the best and significantly superior with lowest plant mortality (9.14% and 14.00%) at 40 and 60 DAS respectively, which was found at par with the RPP (8.47 and 13.32 per cent at 40 and 60 DAS respectively). As regards to green pod yield, the RPP registered highest yield (103.23 q/ha) and found at par with Module-II (102.74 q/ha). The maximum benefit cost ratio (1.53) was recorded in RPP followed by Module-II (1.43) and Module-VI (1.37). Laboratory and field evaluation of four groups of baits materials (sugar, lipid, protein and waste) were assessed. Out of the four sugar based bait materials tested, mixture of honey with boric acid was found to be the most effective in attracting maximum (83.00) number of ants followed by the mixture of molasses with boric acid (55.00). In case of lipid based bait materials, mixture of rice bran oil with boric acid was found to be superior in attracting highest (47.33) numbers of ants followed by mustard oil with boric acid (37.00 nos.). Likewise, in case of protein based bait materials, maximum numbers of ant (35.00) were attracted to the mixture of gram flour with boric acid followed by mixture of dog biscuits with boric acid recording (27.67). Similarly, from the waste based bait materials, mixture of sugarcane trash with boric acid attracted maximum red ants (96.67) followed by mixture of banana peel with boric acid (36.67). Based on the laboratory performance, the above bait materials were evaluated against red ant in both potato and French bean crops under field conditions and compared with an untreated control. Out of eight bait materials, the application of rice bran oil with boric acid was found significantly superior as compared to the rest of the bait materials and could attract highest numbers of red ants in potato (1564.66, 1972.33 and 2636.33 at tuber formation, tuber maturity and harvesting stage) and French bean (1277.00, 1436.66 and 1655.33 at pod formation, pod maturity and harvesting stage) respectively.