Abstract
The Fall armyworm (
Author Contributions
Copyright© 2021
Elsheikh M. Kona Nada, et al.
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Introduction
The Fallarmyworm (FAW), Studies carried out on this pest showed that it is a polyphagous insect of enormous agricultural importance. The larvae can feed on more than 150 plant species, and the adult can produce several generations per year, and the moth can fly up to 100 km/night (Montezano, et, al.; 2018) The first reports on the distribution of FAW in Africa were from West Africa (Georgen, Concerning the economic importance of the FAW, surveys were carried out during 3-4 months in 8 states showed that 6 crops; namely. Maize, Sorghum, Millet, Sesame, Peanut and Tomatoes were affected by this pest. The damage ranged from high (100%) in 2 States (Khartoum and Sennar), to moderate (33.4%) in 2 States (Aljazira and South Kordofan) and low in 4 States (Blue Nile, Al Gadaref, Kassala and Western Darfur). Since its discovery in Sudan, no study has been carried out on its detailed biology. Accordingly, this research was carried out to study the biology of the FAW after its wide distribution in Khartoum State. As a new invasive pest, it is important to understand its life stages and biological parameters in order to allow for planning effective strategy for control measures.
Materials And Methods
During the period from September 2018 up to the end of August 2019, regular surveys were made in the Maize fields infested with FAW ( After adult emergence, ten pairs, each of a male and a female, were released in separate cages. The adults were fed on 10% sugar solution soaked on cotton pads offered in small plastic caps inside the cages and replaced daily. The pre-oviposition, oviposition and post-oviposition periods and number of eggs laid by each female were recorded. The eggs were collected and kept in a circular insect breeding dish and were examined at intervals of 12 hrs, for hatching. After hatching, thirty larvae (n = 30) were reared individually and fed on fresh maize leaf bits which were changed daily. The number of larval instars, larval and pupal durations and longevity of emerging adults and sex ratio were recorded. Annual generations of the FAW were also observed. These procedures of rearing adults and larvae were repeated regularly during the observation periods on the FAW development during the whole year.
Results
In the present study, the biological parameters observed and recorded during the development of the FAW from oviposition up to the adult emergence, within a period of twelve Months. The results are shown in the following During the past decades, large numbers of studies were made on the biology of the FAW in various countries in the world (Igyuve. et, al.; 2018; and Lamsal, et, al.; 2020) The regular observations of the (FAW) made in the present study in the fields, and in the laboratory, showed that its reproduction continued during the whole year round. Under normal laboratory conditions, six generations of the FAW were recorded during its development within Twelve Months. These are shown in According to the observations made, these generations of the FAW can be classified on seasonal bases to the following: two generations (the First and the Second generations) in the autumn, from September to late November. The third generation in the winter, from December to late March. The fourth and the fifth generations in the summer (from April to late June) and the sixth generation in autumn (during July and August). Considering the number of FAW generations per year, the results of the present study are in agreement with those reported by Abraham,
Stage
Range(Days)
Mean ± SD
Pre-oviposition Period
3.00 – 4.00
3.6 ± 0.49
Oviposition Period
2.00 – 3.00
2.8 ± 0. 40
Post-oviposition Period
4.00 – 5.00
4.3 ± 0.46
Female Fecundity (No. of Eggs)
890.00 - 1169
1029.8 ± 139.5
Egg Hatchability(%)
90% - 95%
92.5 ± 2.5
Adult Male Longevity
7.00 – 9.00
8.20 ± 0.75
Adult Female Longivity
9.00 – 12.00
10.80 ± 0.87
MaleTotal Life Cycle(Egg – Adult)
24 – 54
39 ± 15.00
FemaleTotal Life Cycle(Egg – Adult)
26 – 57
41.5 ± 15.5
Generations
Month
Incubation PeriodRange (Days)
Larval DurationRange(Days)
Pupal Duration Range (Days)
AdultL ongevityRange (Days)
Total Life cycle Range (Days)
Normal Lab. Conditions
Temp. oC
Humid.%
1st
9,10
3-5
13-24
7-12
1-13
24-54
27
65
2nd
10,11
3-6
15-39
7-15
2-15
40-74
25
68
3rd
12, 1,2,3
3-10
25-50
18-20
1-20
47-100
21
66
4th
4,5
8-13
29-40
15-20
1-12
53-85
22
70
5th
6,7
3-5
13-30
11-14
2-20
29-69
23
71
6th
7,8
3-5
15-25
7-10
1-15
26-55
30
69
Conclusion
The regular surveys and observations made on the FAW in the present study indicated that, its breeding is continuous through the year round, and so it represents a menace for the different crops in the field. Therefore , it is recommended that, more studies on the biology and ecology of the FAW would be of prime importance to determine a suitable time for its effective management in the future.