Please use this identifier to cite or link to this item: http://prr.hec.gov.pk/jspui/handle/123456789/21479
Title: Bionomics and sustainable management od Red Palm Weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) on Date Palm (Phoenix dactylifera L.)
Authors: Rehman, Gul
Keywords: Agriculture and Veterinary Sciences
Agriculture
Date palm, red palm weevil, entomopathogenic nematodes, fungus, IPM
Issue Date: 2022
Publisher: Gomal University, Dera Ismail Khan
Abstract: The red palm weevil, (Rhynchophorus ferrugineus Olivier) [Coleoptera: Curculionidae] is a notorious insect pest of the palm family around the palm growing areas of the world. As three out of four developmental stages of the red palm weevil are concealed inside the palms, whereas; the adults mostly remain in the same host and leave it only when the apical portion of the palm is completely destroyed, so it is practically difficult to control red palm weevil through the currently available synthetic chemicals. In addition to this, the indiscriminate use of synthetic chemicals causes many serious problems like development of resistance in insect pests, accumulation of residues on date palm, deterioration of environment and causes serious health hazards to human being. In this scenario, the integrated management looks promising paradigm for the control of red palm weevil. A series of experiments were conducted under laboratory and field conditions to collect information about the bionomics and sustainable management of red palm weevil under agro-ecological conditions of Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan. The biology of red palm weevil was studied on six commercially important date palm varieties viz. Dahki, Muzaft, Aseel, Gulistan, Begum Jungi and Fasley under controlled environmental conditions whereas, in another experiment biology of red palm weevil was studied under a range of temperatures i.e. 15, 20, 25, 30, 35 and 40°C with 65% R.H and 10:14h D:L regimes. The findings revealed that the Dhakki variety was the most susceptible for red palm weevil having maximum number of eggs hatching and weight losses whereas; Fasley variety was found the least susceptible having least egg hatching percentage and weight losses. The maximum total larval developmental duration of 87.2 days was recorded on the variety Fasley which decreased to 64.8 days when red palm weevils were cultured on Dhakki variety. The maximum survival (93.42%) was recorded on variety Dhakki while the lowest survival (66.41%) was recorded on variety Fasley. The maximum adult longevity of female weevils (110 days) was recorded on variety Dhakki while minimum adult longevity of 50.27 days was recorded on variety Fasley. The rearing temperature also significantly influenced the biology and reproduction of red palm weevil. Among the tested temperature regimes, the 30°C was found most suitable for the development, survival and reproduction of the red palm weevil. The maximum eggs hatching (79.60 %), minimum total larval developmental duration (1-7 instar) (39.41 days), maximum larval survival (44.60), pupal formation (73.40), adult emergence (100%), life span of adult weevils (123.20 and 120.80 days) and fecundity (181.40) was noted at 30°C. In contrast to this, the minimum eggs hatching, longest developmental duration, minimum survival and reproduction was recorded at the minimum temperature (15°C). Overall, the lower temperatures (15°C, 20°C) and highest temperature (40°C) were found unsuitable and had negative effects on the development, survival and reproduction of red palm weevil. The experiments to investigate the efficacy of trunk injection technique indicated that the chemical insecticide emamectin benzoate was found most effective on both naturally infested and artificially infested date palm plants. maximum reduction in the infestation level of palm weevil was recorded on palms treated with Emamectin benzoate at all the post treatment intervals followed by Fipronil. Among the treatments, viii the minimum reduction (75.20%) in the population of palm weevils was recorded on palms treated with Tenekil at all the post treatment intervals Studies on the evaluation of sex pheromone traps during 2018-19 and 2019-20 showed that the peak population of the weevils was noted during the months of April to October at all the surveyed locations indicating that these months were favorable for the survival of red palm weevil. The population of red palm weevil started declining during the month of October. The minimum population was recorded during the cooler months of November, December, January and February. The interaction between the meteorological factor and number of adult weevil captures revealed strong correlation between the temperature and number of weevils captured at all the surveyed locations. The entomocidal evaluation of entomopathogenic fungi, B. bassiana indicated that the maximum larval duration was noted when 5th instar larvae of red palm weevil were cultured on the maximum concentration (1 × 108) of B. bassiana, whereas; minimum total larval duration was recorded on the lowest concentration (1 × 104) of B. bassiana. In contrast to this, the larval and pupal weight and adult longevity of weevils decreased by increasing the concentration of the fungus, B. bassiana. The maximum longevities of adult male and females were noted at the lowest concentration, whereas; the minimum values were noted at the highest concentration. The rate of mortality of 5th, 6th instar and adult weevils varied significantly at different post-treatment intervals and concentrations tested. The maximum mortality of red palm weevil was observed at the highest concentration which decreased by decreasing the concentration of B. bassiana. Studies on the infective potential of entomopathogenic nematodes indicated that S. carpocapsae and H. bacteriophora with 94.68 and 92.68% infection were found most effective EPN species against red palm weevil larvae. The aforementioned EPNs were found most infective when pupae of red palm weevil were treated and resulted into 83.60 and 80.20% infested pupae. It was noted that adult emergence is the better option for EPN evaluation compared to dissection of insect. The S. carpocapsae was found most effective against 6th instar larvae of red palm weevil and caused 100% mortality at 240 hours after treatment; whereas; S. glesri and S. feltiae were found least pathogenic and caused 70 and 76% mortality. All the evaluated nematode species were found highly infective under field conditions. The S. carpocapsae was found most pathogenic causing 83.60% mortality of red palm weevil. The experiments to evaluate the effect of different integration tactics under field conditions, revealed that the combination of B. bassiana and S. carpocapsae provided maximum control of the weevils followed by the combination of S. carpocapsae + emamectin benzoate, the combination of B. bassiana + S. carpocapsae + emamectin benzoate and by the combination of entomopathogenic fungus, B. bassiana + emamectin benzoate. The combine use of chemical insecticide (emamectin benzoate) and entomopathogenic fungus (B. bassiana) and nematode (S. carpocapsae) provided additive and synergistic effects against red palm weevil in comparison to single use of nematode, fungus or chemical insecticide. Overall; the integrated use of chemical insecticide, emamectin benzoate, the entomopathogenic fungus (B. bassiana) and nematode (S. carpocapsae) is better option for the sustainable management of red palm weevil.
Gov't Doc #: 27485
URI: http://prr.hec.gov.pk/jspui/handle/123456789/21479
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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