J. stored Prod. Res. Vol. 29, No. 1, pp. 49-52,...
J. stored Prod. Res. Vol. 29, No. 1, pp. 49-52, 1993
0022-474X/93 $6.00 + 0.00
Prjnted in Great Britain. Al1 rights reserved
Copyright 0 1993 Pergamon Press Ltd
RESISTANCE TO CALLOSOBRUCHUS MACULATUS F.
5 Eb
(COL., BRUCHIDAE) IN SOME COWPEA VARIETIES
FROM SENEGAL
DOGO SECK*
Institut Sénégalais de Recherches Agricoles (I.S.R.A.), BP 17 Station de Nioro du Rip, Sénégal
(Received for publication 18 August 1992)
Ahstract-Seeds of 80 varieties from the Senegal cowpea breeding program collection were tested for
bruchid resistance in a five replication study. Significant differences among the varieties were found in
oviposition, progeny and bruchid emergence. The variety 58-57 which is that most grown in Senegal
appeared highly susceptible. On the other hand, 6 varieties (59-12; 58-28; 66-50; 66-S; 58-16 Dl and 59-26)
showed a high level of resistance. The basis of that resistance is under investigation SO that the incidence
of the cowpea weevil in Senegal cari be reduced by selective breeding of cowpea varieties.
Key words-bruchid resistance, Vigna unguiculata, Callosobruchus
maculatus, Senegal.
INTRODUCTION
Cowpea, Vigna unguiculata (L.) Walp. is an important food trop in tropical countries, specially
in West Africa where it is a cheap source of protein (Labeyrie, 1981).
This trop is prone to heavy damage by Callosobruchus maculatus F., the cowpea weevil. Initial
infestation occurs in the field prior to harvest and from there the insects are carried to storehouses
where the population cari build up rapidly (Prevett, 1961; Huignard, 1985). Caswell (1973)
estimated that in Nigeria alone, the dry weight loss due to C. maculatus exceeded 2900 tonnes each
year. In Senegal, damage in terms of holed seeds cari increase to 99% after 6 months of storage
(Seck et al., 1991). In addition, bruchid infestation affects seed quality and cari reduce germination
abiiity to less than 20% after 4 months (Seck, unpublished). The control of C. maculatus in
developing countries relies heavily on the use of synthetic chemicals which cause, numerous
environmental, social and financial side effects that are well documented (Huignard, 1985;
Egwuatu, 1987). TO reduce this dependence on chemicals and to assist farmers in reducing losses
due to bruchids, efforts could be placed in developing alternative control methods, such as varietal
resistance. The purpose of the present paper is to locate sources of resistance through an intensive
$creening of varieties collected and provided by the Senegal Cowpea breeding program.
MATERIALS AND METHODS
Eighty cowpea varieties the seeds of which were provided by ISRA (Institut Sénégalais de
Becherches Agricoles) were evaluated in order to assess their resistance to C. maculatus F.
Parental insects were allowed to mate and lay eggs on each tested variety for 10 days. They were
then removed and eggs laid on the boxes and on seeds were counted.
Bioassays for bruchid resistance were performed using 90 mm dia petri dishes. Ten healthy seeds
of each variety were infested in five replications with 3 freshly emerged C. maculatus adults
(1$ + 29). Test insects were taken from laboratory cultures maintained for several generations on
the Senegalese variety 58-57.
Experiments were conducted in constant conditions (30°C and 60% r.h.). About 25 days after
infestation (DAI) when Fl adults started emerging, a daily Count of bruchids emerged in each box
was performed unti142 DAI. Based on the total adults emerged from each variety and the number
of eggs laid on seeds, the percentage adult emergence was calculated. At the same time, the mean
number of eggs per seed was calculated for each variety. An analysis of variante and Duncan’s
multiple range test were performed to rank the varieties according to their resistance to the pest.
“Present address: Unité de Zoologie générale et appliquée, Faculté des Sciences agronomiques B-5030 Gembloux, Belgique.
49
5 0
DOGO !sECK
Table 1. Average percentage adult emergeace of the cowpea seed
beetle in 80 varieties from Senegal
% adult
% adult
Varieties
emergence
Varieties
ememence
66-67
79.21
A
66-76
30.56
A-H
58-57
76.11
AB
59-13
30.27
A-H
58-79 T
70.49
A-C
58-191
29.09
A-H
66-65
67.37
A-D
58-74-D,-B,
29.98
A-H
58-79-D,-B,
63.92
A-E
58-39
28.57
A-H
58-29
62.20
A-F
66-47
28.13
A-H
58-12
50.04
A-G
58-74-D&,
27.63
A-H
66-14
58.12
A-G
58-95-D,
27.22
A-H
66-41
56.46
A-G
66-73
21.05
A-H
66-53
55.88
A-G
5H-81
27.03
A - H
66-69
55.78
A-G
66-2
26.61
A-H
66-48
55.04
A-H
59-30
26.56
A-H
66-61
53.22
A-H
58-3
25.15
A-H
59-24 T
51.42
A-H
66-21
25.15
A - H
66-36
SO.73 A-H
66-64
24.64
A-H
58-161
50.43
A-H
58-95-D,
24.50
A-H
66- 1
50.40
A-H
58-20
24.04
B-H
66-38
48.96
A-H
58-43
23.05
B-H
66-57
48.16
A-H
59-20 B
20.93
C-G
66-72
47.87
A-H
5X-51
20.82
C-H
58-52
43.95
A-H
66-22
20.40
C-H
66-40
43.41
A-H
5H- 154
20.18
C-H
63-6
42.87
A-H
5X-95-Dz-B,
19.68
C-H
66-42
41.99
A-H
58-16 T
19.56
C-H
58-44
40.78
A-H
58-80
18.67
C-H
66-66
40.12
A-H
58- 162
18.46
C-H
58-74-D&,
39.94
A-H
59-2 1
17.75
C-H
58-74
38.88
A-H
60-27
17.24
C-H
58-24
38.55
A-H
59-25
16.18
C-H
58-4
36.64
A-H
66-49
15.69
A-H
66-77
36.25
A-H
58-30
15.37
C-H
58-19
36.05
A-H
77-70
13.33
D-H
58-47
35.79
A-H
58-2
10.53
E-H
58-41
34.54
A-H
58-79-Dz-A,
10.29
E-H
58-47
33.69
A-H
58-16-D,
9.08
E-H
58-79-Dz-A,
33.16
A-H
66-5
7.06
F-H
58-32
32.36
A-H
6b-50
6.78
GH
58-151
31.14
A-H
58-28
6.55
GH
58-58
31.00 A-H
59-12
6.01
GH
5X-146
30.77 A-H
59-26
0.00
H
W i t h i n a c o l u m n , means followed b y t h e same letters a r e net
significantly different at the 5% level.
RESULTS AND DISCUSSION
Percentage adult emergence (Table 1) ranged from 79.2% in the variety 66-67 to 0% for 59-26.
Analysis of variante indicated significant differences between varieties at P = 0.05. Of 80 varieties
. .
tested, only 6 of them (59-26, 59-12, 58-28, 66-50, 66-5 and 58-16-Dl) scored less than 10%.
Mean number of eggs laid per seed (Table 2) ranged from 7.38 in the variety 58-57 to 0.16 eggs
per seed for variety 66-5. The comparison of this parameter with the percentage of adult emergence
shows that except for the variety 59-12 (6.08 eggs per seed), the other 5 varieties which permitted
less than 10% adult emergence also :had a low number of eggs per seed, ranging from 0.16 in variety
66-5 to 1.20 in variety 66-50, that is to say 46 to 6 times less than the most sensitive variety 58-57.
Adult progeny (Table 3) ranged from 54 in the variety 58-57 to 0 in 59-26. Once again data
revealed the same tendency as that observed for adult emergence and the number of eggs per seed.
Emergence patterns (Table 4) show that resistant variety 58-16Dl was characterized by a delayed
adult emergence in contrast to the :most sensitive one that showed an extremely rapid emergence
with most of the insects emerging during the first five days following the beginning of Fl emergence.
Similar observations have also been made by Singh et al. (1985) on three resistant cowpea
lines (TVu 2027, TVu 11952 and TVu 11953) compared to the very susceptible Nigerian variety
“Ife Brown”.
Our present results on the testing of a part of the Senegalese cowpea gene pool indicate that the
following varieties: 59-12; 58-28; 66-50; 66-5; 58-16-Dl; 59-26 have resistance to attack by C.
maculatus. They also demonstrate the high sensitivity of 58-57 which is the most cultivated variety
Table 2. Number of eggs laid by Callosobruchux maculatus females on seeds
Table 3. Number of F, Cailosobruchur
maculatus adults from seeds of 80
of 80 cowpea varieties from Senegal
cowpea varieties from Senegal
Mean number of
Mean number of
Mean number of
Mean number of
Varieties
eggs/=d
Varieties
QJF/@
Var&ies
adults emerged
Varieties
adults emerged
58-57
7.38
A
58-24
1.84
C-F
58-57
54.00
A
58-154
9.40
C-G
5 8 - 9 5 - D ,
7.34
A
58-146
1.82
C-F
5 8 - 9 5 - D ,
35.00
B
66-2
9.20
C-G
66-40
6.96
AB
58-12
1.78
C-F
66-67
32.00
BC
58-51
9.20
C-G
59-12
6.08
A-C
66-73
1.76
C-F
5 8 - 7 9 - T
30.40
B-D
58-39
9.20
C-G
58-79-Dz-B,
5.50
A-D
66-27
1.76
C-F
6 6 - l
26.00
B - E
58-44
9.20
C-G
59-21
5.10
A-E
58-19
1.74
C-F
66-40
25.80
B - E
58-74-D,-B,
9.00
C-G
58-79 T
4.64
A-F
58-161
1.70
C-F
66-66
25.00
B-F
66-22
9.00
C-G
6 6 - l
4.34
A-F
58-43
1.64
C-F
58-79-D,-B,
24.00
B-G
5 8 - 1 6 - T
8.80
C-G
66-67
4.08
A-F
66-61
1.58
C-F
6.5-53
23.20
B-G
59-20-B
8.80
C-G
66-57
3.82
A-F
5 8 - 9 5 - D ,
1.48
D-F
66-14
22.00
B-G
58-95-4
8.60
C-G
59-20 B
3.74
A-F
58-162
1.48
D-F
66-41
21.10
B-G
66-76
8.40
C-G
66-3
3.68
A-F
58-47
1.46
D-F
66-36
21.20
B-G
59-21
8.40
C-G
58-16 T
3.64
A-F
58-74
1.32
D-F
66-69
19.00
B-G
58-32
8.00
C-G
66-41
3.54
A-F
66-2
1.28
D-F
63-6
18.80
B-G
59-13
7.80
C-G
66-38
3.52
A-F
58-39
1.28
D-F
66-61
16.20
B-G
59-30
7.20
C-G
66-66
3.48
A-F
58-29
1.22
D-F
66-42
16.20
B-G
58-3
7.00
C-G
66-21
3.46
A-F
66-50
1.20
D-F
66-38
15.60
B-G
58-79-Dz-A,
6.80
C-G
58-81
3.46
A-F
58-32
1.16 D-F
58-30
15.60
B-G
66-47
8.80
C-G
58-52
3.10
A-F
66-64
1.16 D-F
66-21
15.40
B-G
59-12
6.40
C-G
66-69
2.92
B-F
5 9 - 2 4 T
1.10 D-F
66-57
15.40
B-G
58-95-D,-B,
6.20
E - G
66-72
2.88
B-F
66-65
1.10 D-F
66-48
15.20
B-G
58-77
6.20
E - G
66-14
2.86
B-F
66-76
1.08 D-F
66-72
15.20
B-G
58-151
6.20
E - G
58-4
2.74
B-F
58-77
0.98
D-F
58-161
14.60
B-G
66-64
5.60
E - G
58-3
2.70
B-F
66-47
0.90
E F
58-19
14.40
B-G
58-58
5.00
E - G
66-36
2.58
C-F
66-77
0.82
E F
58-81
14.20
B-G
58-80
4.80
E - G
59-30
2.56
C-F
58-151
0.80
E F
58-12
14.00
B-G
66-77
4.20
E - G
58-20
2.54
C-F
59-25
0.70
E F
58-74-D&
14.00
B-G
58-191
3.80
E - G
58-154
2.42
C-F
58-58
0.66
E F
58-74-D&
13.80
B-G
59-25
3.60
E - G
66-42
2.38
C-F
58-41
0.62
E F
58-146
-
13.40
B-G
58-41
3.60
E - G
58-74-D&
2.36
C-F
58-28
0.62
E F
58-20
11.80
B-G
66-27
3.20
E - G
66-48
2.36
C-F
58-80
0.62
E F
58-52
11.60
B-G
66-49
3.00
E - G
59-13
2.30
C-F
58-95-Dz-Bz
0.62
E F
66-65
11.00
C-G
66-50
2.00
E - G
58-79-Dz-A,
2.26
C-F
66-49
0.54
F
5 9 - 2 4 - T
10.80
C-G
58-28
2.00
E - G
58-30
2.14
C-F
58-16-D,
0.52
F
5 8 - 4 7 - T
10.80
C-G
58-162
1.80
E - G
58-74-D,-8,
2.08
C-F
58-79-Dz-A,
0.52
F
58-4
10.60
C-G
58-79-Dz-A,
1.20
FG
66-22
2.04
C-F
58-191
0.46
F
58-29
10.40
C-G
58-2
1.00
FG
58-74-D&,
1.98
C-F
66-70
0.26
F
58-43
10.40
C-G
5 8 - 1 6 - D ,
1.00
FG
58-44
1.94
C-F
59-26
0.20
F
58-74
10.20
C-G
66-70
1.00
FG
66-57
1.88
C-F
58-2
0.18
F
58-24
10.00
C-G
66-5
0.60
G
58-51
1.86
C-F
66-5
0.16 F
66-73
9.80 C-G
59-26
0.00 G
Within a column, means followed by the same letters are not significantly
Within a column, means followed by the same letters are not significantly
different at the 5% level.
different at the 5% level.
52
DOGO SECK
Table 4. Brucbid ememence uattern in a selected resistant and a susceutible varietv
Number of bruchids emerged
(days post-infestation)
-
-
.-
Total adults
Variety
25
26
21
28
33
34
35
36
31
40
4 1
42
emeraed
58-16-D,
0
0
0
0
0
3
0
0
0
0
2
0
5
58-57
1 7
1 8
25
28
44
9
3
32
6
2 1
2
10
217
Data are based on 50 seeds samples.
in Center and Northern tenter of Senegal and suggest the need to improve its resistance to the
cowpea weevil.
From this point of view, the six cited varieties are potential sources of resistance to the cowpea
weevil. Nevertheless, further studies have to be conducted on their morphological and biochemical
characters. Nwanze et al. (1975, 19176), and Gatehouse et al. (1979) demonstrated the importance
of such factors in the resistance of V. unguiculattz varieties to C. maculatus.
Acknowledgementî-Sincere
thanks are due to N. Cisse for providing the varieties, B. Sidibe for his technical assistance
and Miss A. Van Meensel who kindly typed the manuscript. 1 am grateful to Dr J.-L. Hemptinne, Pr. Ch. Gaspar and
an anonymous referee for their valuable comments on the paper.
This work was supported in part by the Bean/Cowpea Collaborative Research Support Program (CRSP) under the
ISRA SenegallUniversity of California-Riverside Project.
R E F E R E N C E S
Caswell G. H. (1973) The impact of infestation on commodities. Trop. stored Prod. Inf. 25, 19.
Egwuatu R. 1. (1987) Cmrent status of conventional insecticides in the management of stored product insect pests in the
tropics. Insect Sci. Applic. 8, 695-701.
Gatehouse A. M. R., Gatehouse J. A., Dobie P., Kilminster P. and Boulter D. (1979) Biochemical basis of insect resistance
in Vignaf unguiculata.
J. Sci. Food Agric. 30, 948-958.
Huignard J. (1985) Importance des pertes dues aux insectes ravageurs des graines: problèmes posés par la conservation des
légumineuses alimentaires, sources de protéines végétales. Cuh. Nutr. Diét., XX 3, 193.-199.
Labeyrie V. (1981) Vaincre la carence proteique par le développement des légumineuses alimentaires et la protection de
leurs récoltes contre les bruches. Food Nutr. Bull. 3, 24-38.
Nwanze K. F. and Horber E. (1976) Seed coats of cowpeas affect oviposition and larval development of Cullosobruchus
maculatus. Environ. Enf. 5, 213-218.
Nwanze K. F., Horber II. and Pitts C. W. (1975) Evidence for ovipositional preference of Cullosobruchus
muculatus for
cowpea varieties. Environ. Ent. 4, 409-412.
Prevett P. F. (1961) Field infestation of cowpea (Vigna unguiculuta)
pods by beetles of the families Bruchidae and
Curculionidae in Northern Nigeria. Bull. Ent. Res. 52, 635-646.
Seck D., Sidibé B., Haubruge E., Hemptinne J.-L. and Gaspar Ch. (1991) La protection chimique des stocks de Ni&é et
de maïs contre les inse:ctes au Sénégal. Med. Fac. Landbouww. Rijksuniv. Gent. 56/3b, 1225-1234.
Singh B. B., Singh S. R. a.nd Adjadi 0. (1985) Bruchid resistance in cowpea. Crop Sci. 25, 736739.
0022-474X/93 $6.00 + 0.00
Prjnted in Great Britain. Al1 rights reserved
Copyright 0 1993 Pergamon Press Ltd
RESISTANCE TO CALLOSOBRUCHUS MACULATUS F.
5 Eb
(COL., BRUCHIDAE) IN SOME COWPEA VARIETIES
FROM SENEGAL
DOGO SECK*
Institut Sénégalais de Recherches Agricoles (I.S.R.A.), BP 17 Station de Nioro du Rip, Sénégal
(Received for publication 18 August 1992)
Ahstract-Seeds of 80 varieties from the Senegal cowpea breeding program collection were tested for
bruchid resistance in a five replication study. Significant differences among the varieties were found in
oviposition, progeny and bruchid emergence. The variety 58-57 which is that most grown in Senegal
appeared highly susceptible. On the other hand, 6 varieties (59-12; 58-28; 66-50; 66-S; 58-16 Dl and 59-26)
showed a high level of resistance. The basis of that resistance is under investigation SO that the incidence
of the cowpea weevil in Senegal cari be reduced by selective breeding of cowpea varieties.
Key words-bruchid resistance, Vigna unguiculata, Callosobruchus
maculatus, Senegal.
INTRODUCTION
Cowpea, Vigna unguiculata (L.) Walp. is an important food trop in tropical countries, specially
in West Africa where it is a cheap source of protein (Labeyrie, 1981).
This trop is prone to heavy damage by Callosobruchus maculatus F., the cowpea weevil. Initial
infestation occurs in the field prior to harvest and from there the insects are carried to storehouses
where the population cari build up rapidly (Prevett, 1961; Huignard, 1985). Caswell (1973)
estimated that in Nigeria alone, the dry weight loss due to C. maculatus exceeded 2900 tonnes each
year. In Senegal, damage in terms of holed seeds cari increase to 99% after 6 months of storage
(Seck et al., 1991). In addition, bruchid infestation affects seed quality and cari reduce germination
abiiity to less than 20% after 4 months (Seck, unpublished). The control of C. maculatus in
developing countries relies heavily on the use of synthetic chemicals which cause, numerous
environmental, social and financial side effects that are well documented (Huignard, 1985;
Egwuatu, 1987). TO reduce this dependence on chemicals and to assist farmers in reducing losses
due to bruchids, efforts could be placed in developing alternative control methods, such as varietal
resistance. The purpose of the present paper is to locate sources of resistance through an intensive
$creening of varieties collected and provided by the Senegal Cowpea breeding program.
MATERIALS AND METHODS
Eighty cowpea varieties the seeds of which were provided by ISRA (Institut Sénégalais de
Becherches Agricoles) were evaluated in order to assess their resistance to C. maculatus F.
Parental insects were allowed to mate and lay eggs on each tested variety for 10 days. They were
then removed and eggs laid on the boxes and on seeds were counted.
Bioassays for bruchid resistance were performed using 90 mm dia petri dishes. Ten healthy seeds
of each variety were infested in five replications with 3 freshly emerged C. maculatus adults
(1$ + 29). Test insects were taken from laboratory cultures maintained for several generations on
the Senegalese variety 58-57.
Experiments were conducted in constant conditions (30°C and 60% r.h.). About 25 days after
infestation (DAI) when Fl adults started emerging, a daily Count of bruchids emerged in each box
was performed unti142 DAI. Based on the total adults emerged from each variety and the number
of eggs laid on seeds, the percentage adult emergence was calculated. At the same time, the mean
number of eggs per seed was calculated for each variety. An analysis of variante and Duncan’s
multiple range test were performed to rank the varieties according to their resistance to the pest.
“Present address: Unité de Zoologie générale et appliquée, Faculté des Sciences agronomiques B-5030 Gembloux, Belgique.
49
5 0
DOGO !sECK
Table 1. Average percentage adult emergeace of the cowpea seed
beetle in 80 varieties from Senegal
% adult
% adult
Varieties
emergence
Varieties
ememence
66-67
79.21
A
66-76
30.56
A-H
58-57
76.11
AB
59-13
30.27
A-H
58-79 T
70.49
A-C
58-191
29.09
A-H
66-65
67.37
A-D
58-74-D,-B,
29.98
A-H
58-79-D,-B,
63.92
A-E
58-39
28.57
A-H
58-29
62.20
A-F
66-47
28.13
A-H
58-12
50.04
A-G
58-74-D&,
27.63
A-H
66-14
58.12
A-G
58-95-D,
27.22
A-H
66-41
56.46
A-G
66-73
21.05
A-H
66-53
55.88
A-G
5H-81
27.03
A - H
66-69
55.78
A-G
66-2
26.61
A-H
66-48
55.04
A-H
59-30
26.56
A-H
66-61
53.22
A-H
58-3
25.15
A-H
59-24 T
51.42
A-H
66-21
25.15
A - H
66-36
SO.73 A-H
66-64
24.64
A-H
58-161
50.43
A-H
58-95-D,
24.50
A-H
66- 1
50.40
A-H
58-20
24.04
B-H
66-38
48.96
A-H
58-43
23.05
B-H
66-57
48.16
A-H
59-20 B
20.93
C-G
66-72
47.87
A-H
5X-51
20.82
C-H
58-52
43.95
A-H
66-22
20.40
C-H
66-40
43.41
A-H
5H- 154
20.18
C-H
63-6
42.87
A-H
5X-95-Dz-B,
19.68
C-H
66-42
41.99
A-H
58-16 T
19.56
C-H
58-44
40.78
A-H
58-80
18.67
C-H
66-66
40.12
A-H
58- 162
18.46
C-H
58-74-D&,
39.94
A-H
59-2 1
17.75
C-H
58-74
38.88
A-H
60-27
17.24
C-H
58-24
38.55
A-H
59-25
16.18
C-H
58-4
36.64
A-H
66-49
15.69
A-H
66-77
36.25
A-H
58-30
15.37
C-H
58-19
36.05
A-H
77-70
13.33
D-H
58-47
35.79
A-H
58-2
10.53
E-H
58-41
34.54
A-H
58-79-Dz-A,
10.29
E-H
58-47
33.69
A-H
58-16-D,
9.08
E-H
58-79-Dz-A,
33.16
A-H
66-5
7.06
F-H
58-32
32.36
A-H
6b-50
6.78
GH
58-151
31.14
A-H
58-28
6.55
GH
58-58
31.00 A-H
59-12
6.01
GH
5X-146
30.77 A-H
59-26
0.00
H
W i t h i n a c o l u m n , means followed b y t h e same letters a r e net
significantly different at the 5% level.
RESULTS AND DISCUSSION
Percentage adult emergence (Table 1) ranged from 79.2% in the variety 66-67 to 0% for 59-26.
Analysis of variante indicated significant differences between varieties at P = 0.05. Of 80 varieties
. .
tested, only 6 of them (59-26, 59-12, 58-28, 66-50, 66-5 and 58-16-Dl) scored less than 10%.
Mean number of eggs laid per seed (Table 2) ranged from 7.38 in the variety 58-57 to 0.16 eggs
per seed for variety 66-5. The comparison of this parameter with the percentage of adult emergence
shows that except for the variety 59-12 (6.08 eggs per seed), the other 5 varieties which permitted
less than 10% adult emergence also :had a low number of eggs per seed, ranging from 0.16 in variety
66-5 to 1.20 in variety 66-50, that is to say 46 to 6 times less than the most sensitive variety 58-57.
Adult progeny (Table 3) ranged from 54 in the variety 58-57 to 0 in 59-26. Once again data
revealed the same tendency as that observed for adult emergence and the number of eggs per seed.
Emergence patterns (Table 4) show that resistant variety 58-16Dl was characterized by a delayed
adult emergence in contrast to the :most sensitive one that showed an extremely rapid emergence
with most of the insects emerging during the first five days following the beginning of Fl emergence.
Similar observations have also been made by Singh et al. (1985) on three resistant cowpea
lines (TVu 2027, TVu 11952 and TVu 11953) compared to the very susceptible Nigerian variety
“Ife Brown”.
Our present results on the testing of a part of the Senegalese cowpea gene pool indicate that the
following varieties: 59-12; 58-28; 66-50; 66-5; 58-16-Dl; 59-26 have resistance to attack by C.
maculatus. They also demonstrate the high sensitivity of 58-57 which is the most cultivated variety
Table 2. Number of eggs laid by Callosobruchux maculatus females on seeds
Table 3. Number of F, Cailosobruchur
maculatus adults from seeds of 80
of 80 cowpea varieties from Senegal
cowpea varieties from Senegal
Mean number of
Mean number of
Mean number of
Mean number of
Varieties
eggs/=d
Varieties
QJF/@
Var&ies
adults emerged
Varieties
adults emerged
58-57
7.38
A
58-24
1.84
C-F
58-57
54.00
A
58-154
9.40
C-G
5 8 - 9 5 - D ,
7.34
A
58-146
1.82
C-F
5 8 - 9 5 - D ,
35.00
B
66-2
9.20
C-G
66-40
6.96
AB
58-12
1.78
C-F
66-67
32.00
BC
58-51
9.20
C-G
59-12
6.08
A-C
66-73
1.76
C-F
5 8 - 7 9 - T
30.40
B-D
58-39
9.20
C-G
58-79-Dz-B,
5.50
A-D
66-27
1.76
C-F
6 6 - l
26.00
B - E
58-44
9.20
C-G
59-21
5.10
A-E
58-19
1.74
C-F
66-40
25.80
B - E
58-74-D,-B,
9.00
C-G
58-79 T
4.64
A-F
58-161
1.70
C-F
66-66
25.00
B-F
66-22
9.00
C-G
6 6 - l
4.34
A-F
58-43
1.64
C-F
58-79-D,-B,
24.00
B-G
5 8 - 1 6 - T
8.80
C-G
66-67
4.08
A-F
66-61
1.58
C-F
6.5-53
23.20
B-G
59-20-B
8.80
C-G
66-57
3.82
A-F
5 8 - 9 5 - D ,
1.48
D-F
66-14
22.00
B-G
58-95-4
8.60
C-G
59-20 B
3.74
A-F
58-162
1.48
D-F
66-41
21.10
B-G
66-76
8.40
C-G
66-3
3.68
A-F
58-47
1.46
D-F
66-36
21.20
B-G
59-21
8.40
C-G
58-16 T
3.64
A-F
58-74
1.32
D-F
66-69
19.00
B-G
58-32
8.00
C-G
66-41
3.54
A-F
66-2
1.28
D-F
63-6
18.80
B-G
59-13
7.80
C-G
66-38
3.52
A-F
58-39
1.28
D-F
66-61
16.20
B-G
59-30
7.20
C-G
66-66
3.48
A-F
58-29
1.22
D-F
66-42
16.20
B-G
58-3
7.00
C-G
66-21
3.46
A-F
66-50
1.20
D-F
66-38
15.60
B-G
58-79-Dz-A,
6.80
C-G
58-81
3.46
A-F
58-32
1.16 D-F
58-30
15.60
B-G
66-47
8.80
C-G
58-52
3.10
A-F
66-64
1.16 D-F
66-21
15.40
B-G
59-12
6.40
C-G
66-69
2.92
B-F
5 9 - 2 4 T
1.10 D-F
66-57
15.40
B-G
58-95-D,-B,
6.20
E - G
66-72
2.88
B-F
66-65
1.10 D-F
66-48
15.20
B-G
58-77
6.20
E - G
66-14
2.86
B-F
66-76
1.08 D-F
66-72
15.20
B-G
58-151
6.20
E - G
58-4
2.74
B-F
58-77
0.98
D-F
58-161
14.60
B-G
66-64
5.60
E - G
58-3
2.70
B-F
66-47
0.90
E F
58-19
14.40
B-G
58-58
5.00
E - G
66-36
2.58
C-F
66-77
0.82
E F
58-81
14.20
B-G
58-80
4.80
E - G
59-30
2.56
C-F
58-151
0.80
E F
58-12
14.00
B-G
66-77
4.20
E - G
58-20
2.54
C-F
59-25
0.70
E F
58-74-D&
14.00
B-G
58-191
3.80
E - G
58-154
2.42
C-F
58-58
0.66
E F
58-74-D&
13.80
B-G
59-25
3.60
E - G
66-42
2.38
C-F
58-41
0.62
E F
58-146
-
13.40
B-G
58-41
3.60
E - G
58-74-D&
2.36
C-F
58-28
0.62
E F
58-20
11.80
B-G
66-27
3.20
E - G
66-48
2.36
C-F
58-80
0.62
E F
58-52
11.60
B-G
66-49
3.00
E - G
59-13
2.30
C-F
58-95-Dz-Bz
0.62
E F
66-65
11.00
C-G
66-50
2.00
E - G
58-79-Dz-A,
2.26
C-F
66-49
0.54
F
5 9 - 2 4 - T
10.80
C-G
58-28
2.00
E - G
58-30
2.14
C-F
58-16-D,
0.52
F
5 8 - 4 7 - T
10.80
C-G
58-162
1.80
E - G
58-74-D,-8,
2.08
C-F
58-79-Dz-A,
0.52
F
58-4
10.60
C-G
58-79-Dz-A,
1.20
FG
66-22
2.04
C-F
58-191
0.46
F
58-29
10.40
C-G
58-2
1.00
FG
58-74-D&,
1.98
C-F
66-70
0.26
F
58-43
10.40
C-G
5 8 - 1 6 - D ,
1.00
FG
58-44
1.94
C-F
59-26
0.20
F
58-74
10.20
C-G
66-70
1.00
FG
66-57
1.88
C-F
58-2
0.18
F
58-24
10.00
C-G
66-5
0.60
G
58-51
1.86
C-F
66-5
0.16 F
66-73
9.80 C-G
59-26
0.00 G
Within a column, means followed by the same letters are not significantly
Within a column, means followed by the same letters are not significantly
different at the 5% level.
different at the 5% level.
52
DOGO SECK
Table 4. Brucbid ememence uattern in a selected resistant and a susceutible varietv
Number of bruchids emerged
(days post-infestation)
-
-
.-
Total adults
Variety
25
26
21
28
33
34
35
36
31
40
4 1
42
emeraed
58-16-D,
0
0
0
0
0
3
0
0
0
0
2
0
5
58-57
1 7
1 8
25
28
44
9
3
32
6
2 1
2
10
217
Data are based on 50 seeds samples.
in Center and Northern tenter of Senegal and suggest the need to improve its resistance to the
cowpea weevil.
From this point of view, the six cited varieties are potential sources of resistance to the cowpea
weevil. Nevertheless, further studies have to be conducted on their morphological and biochemical
characters. Nwanze et al. (1975, 19176), and Gatehouse et al. (1979) demonstrated the importance
of such factors in the resistance of V. unguiculattz varieties to C. maculatus.
Acknowledgementî-Sincere
thanks are due to N. Cisse for providing the varieties, B. Sidibe for his technical assistance
and Miss A. Van Meensel who kindly typed the manuscript. 1 am grateful to Dr J.-L. Hemptinne, Pr. Ch. Gaspar and
an anonymous referee for their valuable comments on the paper.
This work was supported in part by the Bean/Cowpea Collaborative Research Support Program (CRSP) under the
ISRA SenegallUniversity of California-Riverside Project.
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