BIONOMICS, POPULATION DYNAMICS AND STANDARDIZATION OF DIFFERENT DOSES OF POISON BAITS AGAINST FALL ARMYWORM, Spodoptera frugiperda (J. E. SMITH) INFESTING MAIZE 3743
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Date
2023-08
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Publisher
JAU JUNAGADH
Abstract
Investigations on “Bionomics, population dynamics and standardization of different
doses of poison baits against fall armyworm, Spodoptera frugiperda (J. E. Smith) infesting
maize” were carried out at Instructional farm, College of Agriculture, Junagadh
Agricultural University, Junagadh during 2022.
For this experiment, duration and measurement of different stages of S. frugiperda
viz., eggs, larva, pupa, adult and were studied. The data on the life cycle of S. frugiperda
revealed that the number of eggs laid by female was 327.4 ± 55.09. As far as the hatching
per cent and the incubation period is concerned, 81.0 ± 5.91 per cent and 2.43 ± 0.67 days
were recorded. Mean period of larval instars i.e., first, second, third, fourth, fifth, sixth was
2.56 ± 0.49, 2.30 ± 0.46, 2.03 ± 0.60, 2.00 ± 0.58, 2.40 ± 0.61, 4.63 ± 0.66, respectively
with a total larval period of 15.93 ± 1.48 days. Pre-oviposition, oviposition and post
oviposition periods were 4.2 ± 0.75, 3.6 ± 0.49, 4.4 ± 0.80 days, respectively. Period of
pupal stage was 9.37 ± 0.91 days. Male and female adult longevity were 8.8 ± 1.17 and
11.6 ± 1.02 days, respectively. Total male and female adult life span were 37.6 ± 1.36 and
40.4 ± 1.62 days, respectively having 1: 1.72 (Male: female) of sex ratio.
The average length and width of eggs was measured 0.34 ± 0.03 and 0.29 ± 0.008
mm. Average length of larval instars i.e., first, second, third, fourth, fifth, sixth was 1.57 ±
0.19, 3.44 ± 0.44, 5.98 ± 0.53, 9.94 ± 0.59, 16.3 ± 1.06, 33.9 ± 1.55 mm, respectively.
Average width of larval instars i.e., first, second, third, fourth, fifth, sixth were 0.31 ± 0.027,
0.64 ± 0.037, 1.88 ± 0.23, 3.08 ± 0.33, 4.74 ± 0.49, 5.89 ± 0.22 mm, respectively. Average
length and width of pupa was 15.94 ± 1.27 and 4.93 ± 0.12 mm. The mean body length
(mm) of the male moths was 15.42 ± 1.25 mm while that of the female moths was 15.08 ±
1.58 mm, respectively. The wing span (mm) of the male moth is 32.77 ± 2.08 mm while
that of the female moths was 32.15 ± 2.40 mm, respectively.
The activity of fall armyworm, S. frugiperda was commenced from 31st SMW i.e.
first week of August (0.98 larva per plant) which gradually increased and attained peak of
5.74 larva per plant during 38th SMW and reached minimum during the 46th SMW (0.21
larva per plant). Plant damage showed its peak by recording 83.33 per cent during the 3rd
week of September 2022 (38th SMW). Cob damage was ranged between 44.61 to 77 per
cent. Correlation studies between meteorological parameters and the S. frugiperda larval
population showed significant positive correlation with mean temperature (r = 0.635*
),
positive correlation with maximum temperature (r = 0.025), minimum temperature
(r = 0.461), bright sunshine hours (r = 0.255), morning relative humidity (r = 0.220), and
evening relative humidity (r = 0.128) and evaporation (r = 0.203), whereas non-significant
negative correlation with wind speed (r = -0.051), rainfall (r = -0.152).
Efficacy of poison baits after 24 hours revealed that S. frugiperda can be effectively
managed by Thiodicarb 75% WP (15 g/ liter of water) + 5 kg jaggery + 25 kg wheat bran/ha
with the highest per cent mortality (93.51%) at 60 g of bait. While, Spinetoram 11.7% SC
(10 ml/10 liter of water) + 5 kg jaggery + 25 kg wheat bran/ha and Indoxacarb 14.5% SC
(30 ml/ liter of water) + 5 kg jaggery + 25 kg wheat bran/ha were next effective treatments
over control.
The chronological order of effectiveness of different poison bait treatments based
on per cent mortality of larva was Thiodicarb 75% WP (15 g/ liter of water) + 5 kg jaggery
+ 25 kg wheat bran/ha (93.51 mean per cent mortality of larva) > Spinetoram 11.7% SC
(10 ml/10 liter of water) + 5 kg jaggery + 25 kg wheat bran/ha (81.73 mean per cent
mortality of larva) > Indoxacarb 14.5% SC (30 ml/ liter of water) + 5 kg jaggery + 25 kg
wheat bran/ha (76.71 mean per cent mortality of larva) > Emamectin Benzoate 5% SG 125
g/ha + 5 kg jaggery + 25 kg wheat bran/ha (75.11 mean per cent mortality of larva) >
Carbosulfan 25% EC 25 ml/liter of water + 5 kg jaggery + 25 kg wheat bran/ha (60.00
mean per cent mortality of larva) at both doses.
From the present investigation, it can be concluded that S. frugiperda passed
through four stages viz.; egg, larva, pupa, adult. It reached its peak activities (5.74 larva per
plant) during 3rd week of September (38th standard meteorological week). S. frugiperda
showed significant positive correlation with mean temperature, minimum temperature and
maximum temperature and negative correlation with rainfall and wind speed. So. For
economical management of S. frugiperda in maize, Thiodicarb 75% WP (15 g/ liter of
water) + 5 kg jaggery + 25 kg wheat bran/ha with 60 g dose is effective