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Subject: Entomology × Author: Dhaliwal, Navneet Kaur × Start date: 2018 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    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.