On-Station Bioefficacy of Neem Seed Extract and Beauveria bassiana 115 for Managing Major Insect Pests of Cowpea in the Sahelian Region of Maradi, Niger

Laouali Amadou^1*, Souleymane Laminou¹, Ousseina Abdoulaye¹, Mahaman Nassirou Oumarou², Roufai Yarifou¹, Nana Hadiza Issa Labo³, Ramatou Bargui Abdoulaye⁴, Ibrahim Boukari Baoua³

¹Entomologie Laboratory II, Institut National de la Recherche Agronomique du Niger, Maradi, Niger.
²Centre Régional de la Recherche Agronomique de Tahoua, CERRA, Tahoua, Niger.
³Faculty of Agronomy, Université Dan Dicko Dan Koulodo de Maradi, Maradi, Niger.
⁴Faculté des Sciences Agronomiques, Université Boubacar Bâ de Tillabéry, Tillabéry, Niger.

DOI: 10.4236/as.2025.161001                

Abstract

Cowpea, Vigna unguiculata L. Walp, is an important food grain legume in Niger facing production losses due to insect pests. This study aims to determine the efficiency of non-chemical methods for managing these pests. A trial was conducted during the 2020 and 2022 cropping seasons at the INRAN station in the Maradi region. A Fischer experimental design with 6 repetitions was used to compare 4 treatments: synthetic chemical pesticide; the entomopathogenic fungus Beauveria bassiana; aqueous extracts of neem seeds, and control. Observations were carried out every three days. The cowpea pod-sucking bug, pod borer, and thrips were the main insect pests recorded. In terms of effectiveness, the synthetic pesticide was the best treatment. It reduced insect pest densities by 71.35% to 90.40% in 2020 and by 35.11% to 42.13% in 2022. Grain yields varied between treatments. Neem seed extract followed the synthetic pesticide and significantly reduced insect infestations in both years. The synthetic pesticide and neem seed extract resulted in yields 3 to 5 times higher than the control treatment in 2020. By contrast, B. bassiana 115 and neem seed extract produced similar yields in 2022. Therefore, the results of this study showed that B. bassiana 115 and neem seed extract have insecticidal potential and could be used as an ecological alternative for managing cowpea insect pests in the Sahel.

Keywords

Vigna unguiculata, Biopesticide, Cowpea, Insect Pest, Niger

1. Introduction

Cowpea, Vigna unguiculata L. Walpers (Fabaceae), is one of the main food grain legumes cultivated worldwide, particularly in West Africa. It is produced in peri-urban and rural regions of tropical and equatorial zones [1]. This crop helps reduce poverty and improves food security due to its high protein content and socioeconomic importance [2] [3] (Stoilova & Pereira, 2013). In addition, its agronomic benefits help improve the nitrogen content of the soil. West Africa produces around 83% of global production [4].

The crop is grown throughout the southern agricultural belt of Niger. In 2022, production was 2,865,884 tons [5]. Despite the crop’s advantages, the yield is less than 400 kg/ha in a farming environment. Abiotic and biotic constraints cause this low productivity. Abiotic constraints include drought, high temperatures, low soil fertility, and soil acidity. Biotic constraints include pathogens and parasitic weeds such as Striga gesnerioides [6]. Insects and pathogens are significant pests, causing yield losses ranging from 30% to 100% in extreme cases [7] [8].

The most frequent pests are Maruca vitrata Fabricius (Lepidoptera: Crambidae), Megalurothrips sjostedti Trybom (Thysanoptera: Thripidae), Aphis craccivora Koch (Homoptera: Aphididae), Clavigralla tomentosicollis Stäl (Hemiptera: Coreidae), and Callosobruchus maculatus F. (Coleoptera: Chrysomelidae Bruchinae) [9] [10].

To control these insect pests, several methods have been categorized into chemical control, biological control, cultural control, physical or mechanical control, integrated control, and varietal resistance [11]. However, chemicals are expensive, present supply difficulties, contribute to environmental pollution, cause loss of biodiversity, and are not safe for human and animal health [12].

It is necessary to develop alternative methods for cowpea pest management. One ecological alternative is the use of natural biopesticides. Among these, the neem (Azadirachta indica A. Juss) biopesticide is widely used and recognized for its insecticidal effect against cowpea insect pests [13]. Neem is a common species in the Sahel and has been quickly adopted as a control method in West Africa [14].

In addition to neem, viruses and fungi are potential biological control agents and important components of integrated insect pest management systems [15]. The effectiveness of viruses against insect pests of agricultural importance has been highlighted by several authors [2] [16]-[20]. Furthermore, other authors have noted the effectiveness of fungi in controlling pests affecting agricultural production [21]-[26]. This study is conducted to evaluate the efficiency of biopesticide spraying on the insect pest population of cowpea crops.

2. Materials and Methods

2.1. Study Area

The study was conducted in Maradi at the experimental site of the Regional Center for Agronomic Research of Maradi (CERRA/INRAN) during the 2020 and 2022 cropping seasons. The INRAN station of Maradi is located in the southern Sahelian zone of Maradi city.

2.2. Plant Material

During the two experimental years, the cowpea variety IT90K-372-1-2 was used. It is resistant to aphids, sensitive to thrips, but resistant to drought (300 - 600 mm) with a vegetative cycle of 70 to 75 days.

The cowpea plants were naturally infested by insect pests on site, including the pod bug (C. tomentosicollis), the cowpea pod borer (M. vitrata), and thrips (M. sjostedti).

2.3. Tested Biopesticides

The neem seed extracts and the entomopathogenic fungus Beauveria bassiana 115 were used in trials conducted in 2020 and 2022. The doses per hectare of the products used are presented in Table 1.

Table 1. Biocides tested and recommended doses per hectare.

Pesticides	Actives ingredients	Doze/ha	References or addresses of companies
Pesticide (PACHA 25 EC)	Acetamipride 10 g/l + Lambda- cyhalothrine 15 g/l	1 liter (PACHA) + 300 ml water	Savana http://www.savana-france.com/ Distributed by: B.F_PROPHYMO: [phone]
Neem seeds extracts	Azadirachtine	12.5 kg (Neem kernel powder) + 250 liters of water	(Jackai et al., 1992)
B. bassiana 115	Microbial fungus (souche 115)	50 g (B.B Powder.) + 5.75 (Soya beam extract) +115 distilled water	IITA-Benin at Abome Calavi.

2.4. Experimental Design

A Fischer block with 4 treatments and 6 repetitions was established. The treatments were randomly assigned to plots. The seeds were sown at a density of 0.75 m × 0.30 m. Each plot consisted of 9 rows and 20 stands per row, totaling 180 stands per plot. The blocks are 3 m apart, with 2 m between plots. The nine rows are arranged for data collection as follows:

The two central rows were kept for grain yield evaluation;

The other two internal rows near the central lines were used for insect pest records. Five randomly selected stands were marked for insect pest data recording. The treatments were as follows: synthetic pesticide, neem seed extracts, Beauveria bassiana 115, and a control without pesticide application.

2.5. Cultural Practices

Land preparation was done with a tractor before the cropping season, and manure was applied for both the 2020 and 2022 campaigns. Sowing occurred on June 12^th, 2020, and June 14^th, 2022. Three weeding were conducted each year. A microdose fertilizer application of NPK 15:15:15 was used. Three phytosanitary treatments were applied in both campaigns. The first spraying occurred at the beginning of the flower buds’ emergence, and subsequent treatments were applied weekly. Harvesting involved manually collecting and weighing the pods from the two rows dedicated to yield and other rows.

2.6. Data Collection

Observations were conducted on 5 stands selected in each plot every three days. The following parameters were noted: total number of flowers per cowpea stand; for Thrips and larvae of M. vitrata, 10 flowers were picked per plot, including 2 flowers at each marked stand (5 stands/plot), and placed in a 90% alcohol solution, then brought to the laboratory and dissected to record the number of insect species; number of pod bug larvae and adults per observation; total number of pods per stand; number of pods damaged by M. vitrata; number of pods damaged by pods bugs; number of M. vitrata larvae in damaged pods. At crop maturity, the pods were harvested and dried. They were threshed, and the seeds obtained from each plot were weighed. The yield was calculated and extrapolated to a hectare. Data transformation was done using the formula:

$Tr=ASIN\sqrt{Proportion}$ (1)

The proportion was obtained by dividing the rate by 100 (Rate/100). The pod infestation rate by insect pests was calculated using the following formula:

$\text{T}=\left(\text{number of pods damaged}*100\right)/\text{Total number of pods}.$ (2)

The yield was calculated based on the following formula:

$\text{R}=\left(\text{Weight of seeds harvested in kg}\right)/\text{surface unit}.$ (3)

2.7. Data Analysis

The means and associated standard errors of all variables were calculated using SPSS20 (Statistical Package for Social Science) software. The analysis of variance (ANOVA) for pod infestation rates by insect pests was conducted after the ASIN transformation to compare the average insect and yield. A non-parametric test (Kruskal-Wallis) was used to compare the rates of pod infestations by insect pests.

3. Results

3.1. Evolution of Insect Population Density per Treatments

Thrips were noted from the 43^rd day after sowing (DAS) at the flowering stage during the 2020 cropping season and from the 30^th DAS for 2022 campaign. Maximum densities were observed at the 64^th DAS for 2020 and at the 52^nd DAS for 2022 campaign (Figure 1). During these peaks, the density was highest in the control treatment for both years and lowest for the pesticide treatment, followed by the Neem seed treatment.

Figure 1. Dynamics of the main insect pest pesticide per spraying and treatments.

The larvae of M. vitrata were noted from the 28^th DAS with the first emerged flowers during 2020 and 2022 agricultural campaigns. The control treatment had the highest density, while the chemical treatment had the lowest population, followed by neem seeds extracts in 2020. In 2022 campaign, the peak of M. vitrata was recorded at the 40^th DAS for all the treatments.

The Adults and larvae of C. tomentosicollis were observed from the 70^th and 58^th days after sowing (DAS) in 2020 and 2022, respectively, but at low densities. The maximum infestations were noted on the 88^th DAS for the pesticide treatment in 2020 campaign and at the 76^th DAS in 2022 and the 79^th day after sowing for the neem seed extracts. A proliferation of the pod bug was noted during the harvest periods for both years, even after the biocides were sprayed.

3.2. Average Number of Insect Pests per Treatment

In the 2020 agricultural campaign, the cumulative average number of thrips observed per 10 flowers varied between the treatments. The highest infestation was recorded in the control plots and those treated with B. bassiana. The second group consisted of treatment with neem seed extract, which had moderate infestations. The thrips population was 2.2 times lower compared to the untreated control plot (Table 2).

Table 2. Average number of thrips, M. vitrata larvae, and pod-sucking bugs per treatment.

Treatments	Year 2020			Year 2022
	Thrips/10 flowers	M. vitrata /10 flowers	Pod Bug/cowpea stand	Thrips/10 flowers	M. vitrata/10 flowers	Pod bugs/cowpea stand
Control	189.33 ± 27.52c	54.00 ± 2.61c	10.23 ± 1.8a	0.71 ± 0.12b	2.07 ± 0.16	5.7 ± 0.8b
B. bassiana 115	130.67 ± 11.52ab	36.50 ± 3.96b	4.83 ± 1.16b	0.78 ± 0.12b	1.76 ± 0.1	2.1 ± 0.3a
Neem seeds extract	86.33 ± 11.07b	16.67 ± 1.99a	4.43 ± 0.62b	0.77 ± 0.13b	1.96 ± 0.14	3.35 ± 0.5a
Pesticide	18.17 ± 4.29a	9.17 ± 2.02a	2.93 ± 0.4b	0.34 ± 0.07a	1.8 ± 0.14	2.55 ± 0.2a
ANoVA	F = 13.96; P < 0.00	F = 42.49; P < 0.00	F = 5.70; P < 0.00	F =3.53; P = 0.014	F = 1.07; P = 0.36	F= 7.23; P < 0.001

Means followed by the same letter are not significantly different (LSD, 5%). The same below.

Plots treated with the synthetic chemical pesticide recorded the lowest level of infestation. The density of thrips was 10.4 times lower compared to the control treatment.

In the 2022 agricultural campaign, the density of Thrips was low with chemical treatment and was comparable to the other treatments (Table 2).

For M. vitrata, the statistical analyses identified three groups during the 2022 agricultural campaign: The first group consists of the control treatment, where the highest levels of infestation were noted. The second group consists of the B. bassiana treatment, which showed a moderate infestation with densities 1.5 times lower compared to control treatments.

The third group consists of neem seed extract and synthetic chemical pesticide treatments. The densities of M. vitrata for these treatments ranged from 3.2 to 5.9 times lower compared to the control treatment.

For the 2022 agricultural campaign, all treatments were statistically similar.

For C. tomentosicollis, pest density per treatment was higher in the control plots (Table 3). The number of larvae and adults of the pest was 3.5 to 8.1 times lower with the biocide compared to the control. In the 2022 cropping season, all treatments were comparable but differed from the control, where the density was maximal (Table 2).

3.3. Damaged Pod Rate

The C. tomentosicollis infestations varied depending on the treatments in 2020 and 2022. In 2020, the infestation level in the control plot was the highest, followed by B. bassiana, which was slightly lower than the control. The infestation was moderate with neem seed extracts and low with the synthetic pesticide treatment.

In 2022, infestations were higher in the control treatment and similar between the treated plots (Table 3).

Table 3. Average rate of pod infestations.

Treatments	Year 2020		Year 2022
	Pod infestations rate by M. vitrata	Pod infestations rate by C. tomentosicollis	Pod infestations rate by M. vitrata	Pod infestations rate by C. tomentosicollis
Control	58.54 ± 2.7d	80 ± 0.86d	16.12 ± 1.8b	14.64 ± 1.7b
B. bassiana	21.11 ± 3a	76 ± 1.7c	10.45 ± 1.6a	11.8 ± 1.5ab
Neem seeds extract	50.5 ± 3c	55.31 ± 3b	9.7 ± 1.3a	7.9 ± 0.86a
Pesticide	40.6 ± 3.6b	50 ± 3.3a	7.4 ± 0.9a	9.7 ± 1.4a
Kruskal W	P < 0.001	P < 0.001	P < 0.001	P = 0.004

3.4. Cowpea Grain Yield

The seed production of the plots varied between treatments. The yield obtained in plots treated with the entomopathogenic fungus B. bassiana was comparable to that obtained in the control treatment. The neem seed extracts recorded a production 3.1 times higher than that obtained in the control plots. The highest production was from plots treated with the synthetic chemical pesticide, with a yield 5.6 times higher than the control plots.

In 2022, the yield of fungus treatment B. bassiana was comparable to neem seed extracts and greater than the control. The highest yield was obtained with pesticide treatment, which was 8.6 times higher than the control (Table 4).

Table 4. Average grain yield per treatment.

Treatments	Average yield (kg/ha)
	2020	2022
Control	116.11 ± 20.82a	251 ± 70a
B.bassiana 115	209.87± 19.32a	817 ± 91.6b
Neem seeds extract	363.94 ± 46.65b	941.3 ± 8b
Pesticide	644.56 ± 49.24c	2161 ± 237.3c
ANoVA	F = 45.28; P < 0.001	F = 222.6; P< 0.001

4. Discussion

The study determined the effectiveness of the tested biocides on the pest population and their damage to the cowpea crop.

The untreated control plots demonstrated the legume’s sensitivity to pest attacks, as noted by several authors [1] [27]. The yield of 116.11 kg/ha obtained in 2020 may be attributed to high attacks by thrips (M. sjostedti), the bug C. tomentosicollis, and the pod borer M. vitrata. These pests were observed from the flowering stage, attacking the flowers and pods. These results confirm the need to develop agro-ecological technologies for pest management.

The synthetic chemical pesticide was significantly more effective in reducing the insect pest’s density, followed by neem seed extracts and the entomopathogenic fungus B. bassiana. This is due to differences in their active ingredients and modes of action.

In general, synthetic chemicals act quickly and remain active for a relatively long time after application compared to biological products and biopesticides [28], which are characterized by biodegradability due to sunlight. In this study, the pesticide was the most effective treatment, leading to a 90.4% reduction of thrips, 83% reduction of M. vitrata larvae, and 71.35% reduction of C. tomentosicollis compared to control plots. In Benin, its effectiveness was demonstrated by [2], a study reporting a 76.87% reduction in the population of thrips and M. vitrata. This information demonstrates the effectiveness of chemical control due to their action on a wide range of insect pests.

Furthermore, their “knockdown” effect caused significant mortality of insect pests, reducing damage to cowpea pods. The number of pods damaged by the pod bug and M. vitrata per cowpea stand experienced reductions of 97.95% and 80.37%, respectively, compared to control plots. These results are similar to those obtained by [29] with pod damage by M. vitrata and the rate pf 40% to 85% by the pod bug [30]. Hence, synthetic pesticides have been attractive for their effectiveness in managing insect pests [31]-[33]. However, excessive use of synthetic pesticides leads to insect resistance and poses risks to human health, consumers, animals, and the environment, as well as causing a significant loss of biodiversity [34]-[36]. These reasons highlight the necessity of using biopesticides.

The neem seed extract was the second most effective treatment after the synthetic pesticide, reducing pest populations by 54.4% to 69.12% compared to untreated control plots. These results are similar to [36], a study conducted in Niger, where a reduction of 58.6% to 85.9% in insect populations was recorded. These findings confirm the efficacy of neem seed extracts on a broad spectrum of insect pests as reported by [37]. The performance of neem extracts as a biopesticide is well known, with documented effectiveness on cowpea insect pests such as C. tomentosicollis, M. vitrata, Anocplenomis curvipes and C. shadabi [37]-[40]. The use of the biopesticide also reduced pod bug damage compared to control plots, with a reduction in pods attacked by M. vitrata of 78.7%, which is close to the 74.5% rate reported by other studies [10].

Treatment with B. bassiana led to a population reduction of 52.8% for C. tomentosicollis and 32.4% for M. vitrata. The infectious effect of beauvericin contributed to affecting the cowpea insect pests.

The synthetic chemical pesticide demonstrates effectiveness, with pod produc-tion 5.6 times greater than the control treatment. Furthermore, the 81.98% increase in yield caused by this product proves its effectiveness. These results are similar to those obtained in a study conducted in Niger, where a yield increase of 88.41% was observed with the synthetic chemical pesticide compared to control plots [16].

The yield increase of 68.10% obtained with the aqueous extracts of neem seeds compared to control plots demonstrates the effectiveness of neem seeds. This can be attributed to the insecticidal effect of azadirachtin contained in the neem seeds. The insecticidal properties of neem, due to azadirachtin present in neem tree parts, are responsible for the plant’s valorization through its safe use in diverse areas. This biopesticide could be an alternative to synthetic chemical pesticides and could be included in the methods for integrated management of leguminous crops in Sahelian regions. To facilitate the adoption of this technology, animated videos in local languages are available on SAWBO: https://nigercowpeaipm.sawbo-animations.org/video/1767.

5. Conclusion

The study compared the effectiveness of biopesticides for controlling the main insect pests of cowpea crops. The results showed that the synthetic chemical pesticide, despite its multiple risks, was the best treatment for all parameters studied, followed by neem seed extracts. Nevertheless, using the entomopathogenic fungus B. bassiana reduced the main insect pests’ infestations and increased yield compared to the control treatment. The effectiveness of B. bassiana was not comparable to synthetic chemical pesticides.

Acknowledgements

This work is undertaken with the activities of axis 6 of the CSAT-IPM project of the National Institute of Agronomic Research of Niger (INRAN) funded by Norway Government. A special thanks to Sahel-IPM project which partially funded this research activity on cowpea insect pests.

Conflicts of Interest

The authors declare that there is no conflict of interest regarding the publication of this article.

References

[1]	Ndjouenkeu, R., Nzossie, E.J.F., Kouebou, C., Njomaha, C., Grembombo, A.I. and Oudanan, K.M. (2010) Le maïs et le niébé dans la sécurité alimentaire urbaine des savanes d’Afrique centrale. In: ISDA, Cirad-Inra-SupAgro, 17p.
[2]	Mehinto, J., Atachi, P., Elegbede, M., Kpindou, O. and Tamo, M. (2014) Efficacité comparée des insecticides de natures différentes dans la gestion des insectes ravageurs du niébé au Centre du Bénin. Journal of Applied Biosciences, 84, 7695-7706. https://doi.org/10.4314/jab.v84i1.1
[3]	Stoilova, T. and Pereira, G. (2013) Assessment of the Genetic Diversity in a Germplasm Collection of Cowpea (Vigna unguiculata (L.) Walp.) Using Morphological Traits. African Journal of Agricultural Research, 8, 208-215.
[4]	FAO (2016) PD 3: Trogoderma granarium Everts. Organizacion de Las Naciones Unidas Para La Alimentacion y La Agricultura, 40. https://assets.ippc.int/static/media/files/publication/es/2016/01/DP_03_2012_Es_2016-01-29.pdf
[5]	MA (2023) République du Niger.
[6]	Horn, L.N., Nghituwamata, S.N. and Isabella, U. (2022) Cowpea Production Challenges and Contribution to Livelihood in Sub-Saharan Region. Agricultural Sciences, 13, 25-32. https://doi.org/10.4236/as.2022.131003
[7]	Harouna, M.A., Baoua, I., Rabe, M.M., Saidou, A.A., Amadou, L. and Tamo, M. (2020) Étude diagnostique des principales contraintes de la culture du niébé (Vigna unguiculata L. Walp) dans les régions de Maradi et Zinder au Niger. Afrique Science, 16, 32-43. http://www.afriquescience.net
[8]	Issoufou, O.H., Boubacar, S., Adam, T. and Boubacar, Y. (2017) Identification des insectes, parasites et évaluation économique de leurs pertes en graines sur les variétés améliorées et locale de niébé en milieu paysan à Karma (Niger). International Journal of Biological and Chemical Sciences, 11, 694-706. https://doi.org/10.4314/ijbcs.v11i2.13
[9]	Dugje, I., Omoigui, L.O., Ekeleme, F., Kamara, A.Y. and Ajeigbe, H. (2018) Production du niébé en Afrique de l’Ouest: Guide du paysan. 65.
[10]	Harouna, M.A., Baoua, I., Lawali, S., Tamò, M., Amadou, L., Mahamane, S., et al. (2019) Essai comparatif de l’utilisation des extraits du Neem et du virus entomopathogène MaviNPV dans la gestion des insectes ravageurs du niébé en milieu paysan au Niger. International Journal of Biological and Chemical Sciences, 13, 950-961. https://doi.org/10.4314/ijbcs.v13i2.30
[11]	Zakari, O.A., Baoua, I., Amadou, L., Tamò, M. and Pittendrigh, B.R. (2019) Les contraintes entomologiques de la culture du niébé et leur mode de gestion par les producteurs dans les régions de Maradi et Zinder au Niger. International Journal of Biological and Chemical Sciences, 13, 1286-1299. https://doi.org/10.4314/ijbcs.v13i3.6
[12]	Ali, S., Ullah, M.I., Sajjad, A., Shakeel, Q. and Hussain, A. (2021) Environmental and Health Effects of Pesticide Residues. Sustainable Agriculture Reviews 48: Pesticide Occurrence, Analysis and Remediation, 2, 311-336.
[13]	Niango, M.B., Sanon, A., Tamo, M., Clémentine/Binso, D. and Issa, D. (2008) Combinaison de la résistance variétale et d’insecticides à base de neem pour contrôler les principaux insectes ravageurs du niébé dans la région centrale du Burkina Faso. Science et Technique, Sciences Naturelles et Agronomie, 30, 113-121.
[14]	Rabe, M.M., Baoua, I., Adeoti, R., Sitou, L., Amadou, L., Pittendrigh, B., et al. (2017) Les déterminants socioéconomiques de l’adoption des technologies améliorées de production du niébé diffusées par les champs écoles paysans dans les régions de Maradi et Zinder au Niger. International Journal of Biological and Chemical Sciences, 11, 744-756. https://doi.org/10.4314/ijbcs.v11i2.17
[15]	McGuire, M.R., Ulloa, M., Park, Y. and Hudson, N. (2005) Biological and Molecular Characteristics of Beauveria bassiana Isolates from California Lygus Hesperus (Hemiptera: Miridae) Populations. Biological Control, 33, 307-314. https://doi.org/10.1016/j.biocontrol.2005.03.009
[16]	Abdoulaye, O.Z., Baoua, I., Boureima, S., Amadou, L., Tamo, M., Mahamane, S., Mahamane, A. and Pittendrigh, B.R. (2018) Etude de l’efficacité des biopesticides dérivés du Neem et de l’entomopathogene MaviNPV pour la gestion des insectes ravageurs du niébé au Niger. Bulletin de La Recherche Agronomique Du Bénin, 83, 16-24.
[17]	Kumari, V. and Singh, N.P. (2009) Spodoptera litura Nuclear Polyhedrosis Virus (NPV-S) as a Component in Integrated Pest Management (IPM) of Spodoptera litura (Fab.) on Cabbage. Journal of Biopesticides, 2, 84-86. https://doi.org/10.57182/jbiopestic.2.1.84-86
[18]	Sokamé, M.B. (2012) Etude des interactions entre le baculovirus MaviNPV, les huiles de neem (Azadirachta indica Juss) et de pourghère (Jatropha curcas L.) pour la lutte contre trois principaux ravageurs du niébé, Vigna unguiculata (L). Walp. (Fabales: Fabaceae). Mémoire d’ingénieur: ESA/UL, 106 p.
[19]	Srinivasan, R., Lee, S.T., Lin, M.Y., Lee, C.Y., Huang, C.C., Hsu, Y.C. and Su, F.C. (2008) Developing an Integrated Pest Management (IPM) Strategy for the Legume Pod Border (Maruca vitrata). Proceedings 23th International Congress of Entomology.
[20]	Tamo, M., Goergen, G.E., Agboton, C. and Srinivasan, R. (2007) Putting Agrobiodiversity to Work: The Cowpea Story.
[21]	Doumandji-Mitiche, B., Halouane, F., Bensaad, H., Bissaad, F. and Cherief El-Harrach (Algeria). Dept. de zoologie agricole et forestiere), A. (Institut national agrono-mique (1999) The Efficiency of Beauveria bassiana (Bals.) against Locusta migratoria and Schistocerca gregaria (Orthoptera: Acrididae). Vol. 64, Mededelingen-Faculteit Land-bouwkundige en Toegepaste Biologische Wetenschappen Universiteit Gent (Belgium).
[22]	Halouane, F., Benzara, A., Doumandji-Mitiche, B. and Bouhacein, M. (2001) Effet de deux entomopathogènes, Beauveria bassiana et Metarhizium flavoviride (Hyphomycètes, Deuteromycotina) sur l’hémogramme des larves de 5èmestade et des adultes de Locusta migratoria migratorioides (Orthoptera: Acrididae). Journal of Orthoptera Research, 10, 331-334. https://doi.org/10.1665/1082-6467(2001)010[0331:eddenb]2.0.co;2
[23]	Inglis, G.D., Goettel, M.S., Butt, T.M. and Strasser, H. (2001) Use of Hyphomycetous Fungi for Managing Insect Pests. In: Butt, T.M., Jackson, C. and Magan, N., Eds., Fungi as Biocontrol Agents: Progress, Problems and Potential, CABI Publishing, 23-69. https://doi.org/10.1079/9780851993560.0023
[24]	Islam, M.T., Castle, S.J. and Ren, S. (2009) Compatibility of the Insect Pathogenic Fungus Beauveria bassiana with Neem against Sweetpotato Whitefly, Bemisia tabaci, on Eggplant. Entomologia Experimentalis et Applicata, 134, 28-34. https://doi.org/10.1111/j.1570-7458.2009.00933.x
[25]	Kpindou, O.K.D., Gbongboui, C., Badou, R., Paa-Kwessi, E., Ackonor, J.B. and Langewald, J. (2005) Optimisation de l’application du Metarhizium anisopliae var. acridum sur le criquet puant, Zonocerus variegatus (Orthoptera: Pyrgomorphidae). International Journal of Tropical Insect Science, 25, 251-258. https://doi.org/10.1079/ijt200585
[26]	Fatima, A., Zohra, K.-T.F., Ghania, T.-H. and Fairouz, S. (2017) Effets des traitements avec le Green muscle® en milieu naturel (Nord-Ouest de l’Algérie) sur les larves de Dociostaurus maroccanus (Thunberg, 1815) et sur l’histologie du tégument. Algerian Journal of Natural Products, 5, 530-540. https://doi.org/10.5281/zenodo.1129350
[27]	Agboton, C. (2004) Potentialités biologiques et écologiques de Ceranisus femoratus (Gahan) (Hymenopzera: Eulophidae) un nouvel ennemi naturel pour lutter contre Megalurothrips sjostedti (Trybom) (Thysanoptera: Thripidae) ravageur du niébé au Bénin. Thèse pour l’obtention du Diplôme d’Etudes Approfondies, Université d’Abomey.
[28]	Tounou, A.K., Sokame, B.M., Akpavi, S., Ganyo, K.K., Ketoh, K.G. and Gumedzo, Y.M.D. (2012) Effets des extraits vegetaux sur la dynamique de populations des insectes ravageurs de niebe, Vigna unguiculata walp, dans le Sud du Togo. Journal de la Recherche Scientifique de l’Université de Lomé, 14, 25-34.
[29]	Muhammad, A., Malgwi, A.M. and Adamu, R.S. (2017) Maruca vitrata (Fabricius) [Lepidoptera: Pyralidae] Larval Population Dynamics as Affected by Intra-Row Spacing, Sowing Dates and Biopesticides on Cowpea. Journal of Scientific Agriculture, 1, 352-364. https://doi.org/10.25081/jsa.2017.v1.887
[30]	Dreyer, H., Baumgärtner, J. and Tamò, M. (1994) Seed‐Damaging Field Pests of Cowpea (Vigna unguiculata L. Walp.) in Benin: Occurrence and Pest Status. International Journal of Pest Management, 40, 252-260. https://doi.org/10.1080/09670879409371893
[31]	Sane, B., Badiane, D., Gueye, M.T. and Faye, O. (2018) Évaluation de l’efficacité biologique d’extrait de neem (Azadirachta indica Juss.) comme alternatif aux pyréthrinoïdes pour le contrôle des principaux ravageurs du cotonnier (Gossypium hirsutum L.) au Sénégal. International Journal of Biological and Chemical Sciences, 12, 157-167. https://doi.org/10.4314/ijbcs.v12i1.12
[32]	Gueye, M.T., Seck, D., Wathelet, J.P. and Lognay, G. (2012) Typologie des systèmes de stockage et de conservation du maïs dans l’est et le sud du Sénégal. BASE.
[33]	Rebek, E.J., Frank, S.D., Royer, T.A. and Bográn, C.E. (2012) Alternatives to Chemical Control of Insect Pests. In: Insecticides-Basic and Other Applications, InTech, 171-196.
[34]	Multigner, L. (2005) Effets retardés des pesticides sur la santé humaine. Environnement, Risques & Santé, 4, 187-194.
[35]	Adam, S., Edorh, P., Totin, H., Koumolou, L., Amoussou, E., Aklikokou, K., et al. (2011) Pesticides et métaux lourds dans l’eau de boisson, les sols et les sédiments de la ceinture cotonnière de Gogounou, Kandi et Banikoara (Bénin). International Journal of Biological and Chemical Sciences, 4, 1170-1179. https://doi.org/10.4314/ijbcs.v4i4.63054
[36]	Abdourahamane, H.M., Ibrahim, B., Tamo, M., Laouali, A., Saadou, M. and Barry, P. (2018) Etude des paramètres de reproduction et de développement de Clavigralla tomentosicollis Stål, 1855 (Hemiptera: Coreidae) et son incidence sur le rendement du niébé dans la région de Maradi au Niger. Revue RAMReS, Science de la Vie, de la Terre et Agronomie, 6, 42-48.
[37]	Jackai, L.E.N., Inang, E.E. and Nwobi, P. (1992) The Potential for Controlling Post‐flowering Pests of Cowpea, Vigna unguiculata Walp. Using Neem, Azadirachta indica A. Juss. Tropical Pest Management, 38, 56-60. https://doi.org/10.1080/09670879209371646
[38]	Prajapati, S., Kumar, N., Kumar, S. and Maurya, S. (2020) Biological Control a Sustainable Approach for Plant Diseases Management: A Review. Journal of Pharmacognosy and Phytochemistry, 9, 1514-1523.
[39]	Epidi, T.T., Alamene, A. and Onuegbu, B.A. (2005) Influence of Different Concentrations of Some Plant Extracts on the Yield and Insect Pests of Cowpea (Vigna unguiculata (L.) Walp). Nigerian Journal of Plant Protection, 22, 65-67.
[40]	Malick, N., Dabire, C.B., Drabo, I., Sanon, A. and Tamoÿ, M. (2008) Combinaison de la résistance variétale et insecticides à base de neem pour contrôler les principaux insectes ravageurs du niébé dans la région centrale du Burkina Faso. Sciences Naturelles et Appliquées, 30, 113-121.