PHOSPHINE RESISTANCE MONITORING, MOLECULAR CHARACTERIZATION AND MANAGEMENT OF Tribolium spp. IN STORED RICE
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Date
2024-03-27
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Acharya N G Ranga Agricultural University
Abstract
Studies on “Phosphine resistance monitoring, molecular characterization
and management of Tribolium spp. in stored rice” was conducted at
Department of Entomology, S.V. Agricultural College, Tirupati and Institute
of Frontier Technology, Regional Agricultural Research Station (RARS),
Tirupati, Acharya N.G. Ranga Agricultural University (ANGRAU), Andhra
Pradesh, India during the year 2021-22.
The red flour beetle, Tribolium castaneum was collected from warehouses
located in seven different districts of Andhra Pradesh viz., Nellore, Chittoor,
Guntur, Krishna, Godavari, Kurnool and Srikakulam. Laboratory reared
susceptible populations collected from RARS, Tirupati storage godown have
been maintained for six to seven generations in insectary, Department of
Entomology, S.V. Agricultural College, Tirupati and used for bioassay
studies using modified FAO method (FAO, 1980). All the seven test
populations were found to be resistant to phosphine, but varied in their level
of resistance compared to susceptible lab population. There was no mortality
recorded in the untreated control. Probit analysis estimated LC50 and LC99
values at 0.80 and 3.86 ppm for laboratory susceptible population
respectively. The LC50 for different Tribolium populations ranged between
25.38 ppm (Nellore population) to 69.95 ppm (Kurnool population)
corresponding to 31.76 and 87.54 fold resistance compared to susceptible
laboratory population.
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Red flour beetle populations collected from eight different locations
were also molecularly characterized through total genomic DNA method
using partial mitochondrial COI gene. The multiple nucleotide sequence
analysis of mitochondrial gene sequences of eight populations revealed that,
Chittoor (T-2022-Ctr), Krishna (T-2022- Krs) and Nellore (T-2022-Nlr)
population shared 100 per cent similarity with Indian populations of
T. castaneum from Kerala (MT506942 and MT499228) and Maharashtra
(MH910055) and T. castaneum population from Bangladesh (MK411585),
Germany (KM439779) and South Korea (ON482353) while 99.8 per cent
similarity with T. castaneum-complete genome (KM244661) sequence from
China.
The mitochondrial COI gene sequences of all the eight populations
collected from Andhra Pradesh were submitted to NCBI (GenBank) and
allotted with accession number viz., Nellore (ON811628), Chittoor (OP024180),
Guntur (ON869466), Krishna (ON797460), Godavari (ON920194), Kurnool
(ON811639), Srikakulam (OP021501) and susceptible lab population
(ON869467).
Different life stages of red flour beetle viz., larva, pupa and adult stages
were irradiated at different doses of gamma radiation viz., 10, 25, 50, 70, 100,
250, 450 and 1000 Gy or left unirradiated as a control using Cobalt-60
Gamma irradiator (Gamma Chamber 5000) facility available at ICAR-Indian
Institute of Horticultural Research (IIHR), Bengaluru.
Mortality of adults was recorded at different time intervals, 1000 Gy
resulted in 100 per cent mortality after one week indicating that dose killed
the beetles efficiently compared to 3 to 4 months survival of Tribolium adults
in the untreated control. Radiation dose of ≥ 50 Gy resulted in complete
sterility of adults and 100 per cent pupal mortality. There was no F1 adult
emergence observed in the irradiated adults. The decreased survival of
emerged adults was recorded with increase in radiation dose and the emerged
adults were not survived from irradiated pupae at ≥ 250 Gy.
Among different life stages, Tribolium larvae were found to be more
susceptible to gamma irradiation with 100 per cent mortality at 250 Gy after
two weeks. None of the larvae had developed into pupae with irradiation dose
of 100 Gy and above. There was no adult emergence from the irradiated grubs
at all the test doses from ≥ 10 Gy. Weight loss of rice infested with immature
stages or adult beetles was significantly reduced by irradiation treatment
whereas 4.74 per cent weight loss was recorded with untreated control after
two months.
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The green synthesis of nano silica encapsulated bioformulations of
neem-azal, acorus oil and clove oil was done using dynamic light scattering
technique which formed the more effective nanoparticles with sizes of 42.2 nm,
130.9 nm and 112 nm and zeta potential of 10.8 mV, -27.4 mV and -61.5 mV
respectively compared to nano silica with 69.4 nm particle size and -23.4 mV
zeta potential.
Effect of nanoformulations and plant products viz., neem-azal, clove
oil, acorus oil, nano silica, nano chitosan, nano silica encapsulated neem-azal,
nano silica encapsulated clove oil and nano silica encapsulated acorus oil
were evaluated against larvae and adults of Red flour beetle, T. castaneum.
Among all biopesticides tested, nano silica encapsulated essential oils were
found to be most promising against T. castaneum as compared to normal
essential oils. Among the nano formulations, nano neem-azal was found very
effective against Tribolium larvae and adults with 100 per cent mortality after
15 days of exposure even in lowest test concentration