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20192
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Subject: Entomology × End date: 2019 × Start date: 2019 × Thesis Type: Ph.D ×
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    Impact of neonicotinoids on honey bees (Apis mellifera Linnaeus) in cotton
    (Punjab Agricultural University, Ludhiana, 2019) Brar, Pushpinder Kaur; Kang, B. K.
    The impact of neonicotinoids on Apis mellifera Linneaus in cotton was studied w.r.t. toxicity studies, effect of imidacloprid on colony development parameters and bees in the cotton field and determination of residues in cotton flowers, nectariferous tissue, pollen and hive products. The dermal toxicity laboratory tests revealed that thiamethoxam was the most toxic (LD50 = 7 ng µL-1) followed by clothianidin (LD50 = 10 ng µL-1), imidacloprid (LD50 = 12 ng µL-1), dinotefuran (LD50 = 3767 ng µL-1), acetamiprid (3780 ng µL-1) and thiacloprid (4460 ng µL-1). In oral toxicity studies, the LD50 oral (48 hr after feeding) was clothianidin (0.032 ng µL-1) > thiamethoxam (0.309 ng µL-1) > imidacloprid (3.832 ng µL-1) > dinotefuram (5.420 ng µL-1) > acetamiprid (420.00 ng µL-1) > thiacloprid (463.807 ng µL-1). The effect on colony development can be attributed to sub lethal effects affecting the memory and orientation of bees. The foraging activities of the bees were also influenced. To estimate imidacloprid residues in cotton flower, nectariferous tissue, pollen, bee bread and honey, QuEChERS method was modified and validated according to SANTE guidelines. Experiment was conducted at Raja Harindra Singh Seed Farm, Faridkot and Regional Research Station, Bathinda with four treatments: seed treatment (of cotton crop var. LH 2076) with imidacloprid at single and at double the recommended dose, foliar application of imidacloprid 200 SL at flowering stage at single (40 g/ acre) and double the recommended dose (80 g/ acre) and Apis mellifera colonies were placed on the edge of the treated crop. In spray treatments at RHSSF, Fdkt, average initial deposits in flowers were found to be 1.84 and 3.36 mg/kg; 0.22 and 0.56 mg/kg in nectariferous tissue and 0.88 and 1.58 mg/kg in pollen and 0.01 and 0.02 mg/kg after 7 days of foliar treatment in unsealed honey and 0 .01 mg/kg at 15 days and 0.01 mg/kg at 21 days after foliar treatment at recommended and double the recommended dosages, respectively while at RRS Bathinda, the initial deposits were found to be 1.95 and 3.50 mg/kg in flowers; 0.24 and 0.66 mg/kg in nectariferous tissue, 0.96 and 1.49 mg/kg in pollen and in unsealed and sealed honey were below determination level at 15 and 21 days at recommended and double the recommended dosages, respectively. The samples of all the substrates in the seed treated and control plots did not reveal the presence of imidacloprid. The half-life of imidacloprid at recommended dose was 1.18 and 1.17 days in cotton flower, 0.70 and 0.67 days in cotton nectariferous tissue and 0.41 and 0.44 days in cotton pollen at RHSSF, Faridkot and RRS Bathinda, respectively.
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    Ecology and management of shoot and fruit borer, Leucinodes orbonalis Gunée in brinjal
    (Punjab Agricultural University, Ludhiana, 2019) Dhaliwal, Navneet Kaur; Aggarwal, Naveen
    The studies on effect of constant and alternating temperatures on development, survival and nutritional indices along with carry-over, genetic variability and management of Leucinodes orbonalis Gunée on brinjal were conducted during 2016-2018 at PAU Ludhiana. The duration of egg, larval, pupal and adult stages declined with increase in constant temperature from 15 to 35oC, indicating accelerated development with rising temperature. Favourable temperature range for total development was found to be 20±1 to 35±1oC. Fastest development was recorded at 35±1oC (21.76±0.28 days) and slowest at 20±1oC (60.55±0.23 days). Survival of different stages was highest at intermediate temperatures of 25 to 30oC, with highest overall survival (62.06%) at 30oC. Pupae exposed to constant temperature of 15oC did not develop in to adults as they enter in diapause. Thermal requirements of immature and adult stages ranged from 62.27 to 160.67 degree days (DD) with threshold of 7.97 to 14.32oC. L. orbonalis required 455.24 DD above a threshold of 14.04oC to complete development from egg to adult stage. With increase in alternating temperatures, duration of life stages of L. orbonalis decreased, with shortest total developmental period of 21.17±0.35 days at highest temperature combination of 35:20oC and longest at 20:15oC (33.43±0.33 days). Maximum fecundity (189.22±5.34 eggs/female) was recorded at 25:20oC, while minimum (114.29±3.79 egg/female) at 35:15oC. Effect of six alternating temperatures on nutritional indices of L. orbonalis revealed that consumption index (CI) and growth rate (GR) were highest at 35:20oC with respective values of 2.72±0.07 and 0.333±0.006. On the other hand, approximate digestibility (AD), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD) were highest at 30:20oC with values of 43.42±0.92, 23.51±0.37 and 55.99±1.37 per cent, respectively. Studies on carry-over revealed that ratoon crop was a major source of carry-over of L. orbonalis to the next season, followed by pruned ratoon (cutting with one hoeing) and uprooted brinjal stalks. Eight alternate host plants (4 vegetables; 4 weeds) of the pest were identified during the surveys at farmers’ field. Among these hosts, European black nightshade (Solanum nigrum Linnaeus), potato (Solanum tuberosum Linnaeus) and tomato (Solanum lycopersicon Linnaeus) were found to be the most preferred hosts, while thorneapple (Datura stramonium Linnaeus) was least preferred on the basis of number of infested samples and under free choice conditions. Genetic variability of L. orbonalis population samples could not be ascertained through RAPD primers. Among the four management modules, bio-intensive IPM (BIPM) module (8.40%) had lowest shoot infestation, while farmers practice (20.67%) had the lowest fruit infestation (number basis). Farmer’s practice and BIPM module produced higher yield of marketable fruits of 464.93 and 442.01 q per ha, providing net returns of Rs. 4,77,865/- and Rs. 4,64,201/-, respectively. But B:C ratio among these two modules was higher in case of BIPM module (4.35), while overall, highest B:C ratio of 4.86 was recorded in chemical control.