“MONITORING OF PHOSPHINE RESISTANCE IN Callosobruchus maculatus (Fabricius) AND ITS MANAGEMENT”
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Date
2024-03-20
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Acharya N G Ranga Agricultural University
Abstract
The research work entitled “Monitoring of phosphine resistance in
Callosobruchus maculatus (Fabricius) and its management” was conducted at
Department of Entomology, S.V. Agricultural College and Institute of Frontier
Technology, Regional Agricultural Research Station, Acharya N. G. Ranga
Agricultural University, Tirupati, Andhra Pradesh during 2020-2021.
A detailed survey of warehouses storing pulses was carried in major pulse
growing districts viz., Chittoor, Kurnool, Guntur, East Godavari and Srikakulam
of Andhra Pradesh to assess the frequency and distribution of phosphine resistance
in Callosobruchus maculatus. Five C. maculatus populations were collected from
five different warehouses primarily storing pulses at the surveyed locations. The
frequency of resistance to phosphine in C. maculatus was evaluated based on the
response of adult insects to discriminating concentration (0.04 mgL-1) of
phosphine over 24 hours of exposure period as suggested by FAO, 1980. The
phosphine bioassay results revealed medium level (51-75%) of resistance to
phosphine in the populations collected from Renigunta (56.66%) in Chittoor
District and Nandyal (53.33%) in Kurnool District whereas, the population from
Amadalavalasa (50%) in Srikakulam District, Kakinada (43.33%) in East
Godavari District and Sattenapalli (36.66%) in Guntur District were found to have
low level (0-50%) of resistance to phosphine. The correlation analysis between the
number of aluminium phosphide fumigations and the percentage of resistance
showed a correlation co-efficient (r) of 0.972.
Molecular characterisation of the five C. maculatus populations collected
from major pulse growing districts of Andhra Pradesh viz., Chittoor, Kurnool,
Guntur, East Godavari and Srikakulam was carried out by using partial
mitochondrial cytochrome B (Cyt B) primer. The nucleotide sequence obtained
were blasted in NCBI database and they were confirmed as C. maculatus with 98
per cent similarity. Intra specific variation of C. maculatus sequences assessed
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through multiple sequence alignment revealed that there were no nucleotide
variations in the nucleotide sequences of the populations collected from five
surveyed location in Andhra Pradesh.
The phosphine resistant C. maculatus populations (Chittoor and Kurnool
Districts) identified through phosphine bioassay were used for resistance
management studies using essential oils viz., clove oil, acorus oil, eucalyptus oil,
orange oil, cedar wood oil and neem oil (each at 1%, 3% and 5% concentrations) at
the rate of 5 ml/kg of seed (green gram) alone and in combination with phosphine
(0.04 mgL-1). The data on adult mortality, fecundity, oviposition inhibition, adult
emergence, grain damage and grain weight loss due to C. maculatus were
recorded. All the essential oils at five per cent concentration in combination with
phosphine recorded 100 per cent mortality of adults of C. maculatus. Neem oil at
five per cent concentration in combination with phosphine recorded lowest
number of eggs (5.33 eggs) and highest per cent oviposition inhibition (94.12%)
whereas orange oil at one per cent concentration recorded highest number of eggs
(75.66 eggs) and lowest per cent oviposition inhibition (16.73%). All the essential
oils at five per cent concentration in combination with phosphine, neem oil alone
at five per cent concentration recorded 100 per cent inhibition of adult emergence,
reduced grain damage (0 to 0.98%) as well as grain weight loss (0 to 0.06%).
Orange oil at one per cent concentration recorded highest per cent of adult
emergence (66.11%), grain damage (19.78%) and grain weight loss (9.20%).
Essential oils at five per cent concentration were found effective by recording
highest adult mortality, lowest oviposition, adult emergence, grain damage and
grain weight loss than essential oils at three per cent and one per cent
concentration.
The germination percentage of green gram seed treated with essential oils
of various concentrations was tested. The per cent seed germination of green gram
treated with five per cent concentrations of essential oils recorded 68.88 to 92.22
per cent whereas seeds treated with one per cent concentration of essential oil
recorded 51.11 to 86.66 per cent. The germination percentage of green gram seeds
treated with essential oils increased with increase in concentration of essential oils
due to low damage caused to green gram seed by C. maculatus at higher
concentrations.