To understand the mechanism of infestation of stored groundnut in farming areas, studies on the inventory and geographical distribution of Caryedon species were carried out in the tree savannah and in producers’ storage structures. The incidence of C. serratus in stored groundnut was evaluated. Inventory and geographical distribution of insects belonging to Caryedon genus was achieved through a sampling in the savannah and producers’ granaries. The inventory and geographical distribution of insects was made throughout Burkina Faso whereas the evaluation of the perforations of groundnut pods was made in the western zone of the country. The results of the inventory showed the presence of two species belonging to Caryedon genus which are C. serratus and C. crampelii. These species are found on the agro-ecological zones of the country. The survival and maintenance of Caryedon species genus are ensured by the presence of plants belonging to various families such as Caesalpiniceae and Mimosaceae. The evaluation of the losses caused by C. serratus in producer’s stored groundnut revealed that the pods perforation rate varied according to the locality. In Toussiana, the rate of perforated pods ranged from 53.72% to 100% in five months while in Karangasso Sembla , for the same conservation time, the rate was in the range from 2.8% to 35%. However it is C. serratus which is responsible for the losses observed in the stored groundnut. Indeed, in the western area of Burkina Faso where more than 25% of the production is realized, 70% of groundnut stocked without treatment is destroyed by this insect after only four months of storage.
The genus Caryedon to which the serratus species belongs was already described under about several names [
Inventory and geographical distribution of insects of the genus Caryedon was carried out in the three agro-ecological areas of Burkina Faso during three consecutive years [
The fruits of the wild host plants found in the different zones were collected. For the plants with pods, 30 fruits were collected on the host plants found in each area. Date and area of sampling were recorded.
SudSudanian zone
North Sudanian zone
Sahelian zone
On each sampled site and place where groundnuts are produced, the collection
of groundnut was carried out in the producers’ storage according to stocks availability. The sampling quantities per producer was 1 kg on average.
The samples of groundnut varieties (SH 470P; RMP12; RMP91; TS 32-1) collected in producer zones were isolated by locality in bottles and observed in the laboratory until the potential emergence of insects. The same procedure was followed for the fruits of the wild plants. At the emergence, the adult insects were identified by the male genitalia method according to Prevett’s determination key (4) for the species of beetles of the genus Caryedon. The identification of plant species was made according to the Sahel trees and shrubs description [
The impact of C. serratus on groundnut storage was evaluated in the localities of Toussiana and Karangasso Sambla. The choice of these localities is justified by the importance of groundnut production and the strong pressure exerted by insects on groundnut stocks. Five producers were selected in each of the two localities and five kilograms of unshelled groundnut, untreated and non-infested- groundnut was given to each producer. The varieties used are those cultivated in the area. Each month, samples were taken to track the level of infestation of groundnut stocks and identify the insects which are present. The samples were returned to the laboratory, the pods were observed to count those which are perforated and those which still contain larvae. To determine the rate of infested pods, the latter were shelled and observed to check those which really contain larvae. The parameters studied were:
- the rate of perforated pods = (Nbr of perforated pods/Nbr of total pods) × 100
- Insects species found in groundnut stocks
The analysis of variance on observed parameters were carried out by the means of XLSTAT software version 6.1.9. When the analysis of variance reveals significant differences, the test of Fisher (LSD) was applied for the comparison of averages at the probability threshold set at 5%. The formula of Abbott [
The sampling of fruits of plant species revealed 2172 adults which were compared with 1193 adults collected from the northern Sudanese zone. In total two species of the genus Caryedon namely C. serratus Olivier and Caryedon crampelii have been identified among the specimens which emerged.
The presence of species of the genus Caryedon was established on all the different zones where the samples were collected (
Results (
Order | Family | Species/genus | Status |
---|---|---|---|
Coleoptera | Bruchidae | Caryedon serratus | I |
Tenebrionidae | Tribolium castaneum | II | |
Sylvanidae | Oryzaephilus surinamensis | II | |
Lepidoptera | Phycitidae | Plodia interpunctella | II |
during storage was infested by four families of insects namely Bruchidae, Tenebrionidae and Sylvanidae which belong to the order of Coleoptera. The fourth family found is Phycitidae which belongs to the order of Lepidoptera.
The main host plants of C. serratus are listed on
Host plants | Family | Northern Sudanese Zone | Southern Sudanese Zone |
---|---|---|---|
Bauhinia rufescens (Lam.) | Caesalpiniceae | + | + |
Cassia sieberiana (D.C) | Caesalpiniceae | + | + |
Piliostigma reticulatum (DC.) Hochst | Caesalpiniceae | + | + |
Piliostigma thonningii (Schum.) Miln-Redh | Caesalpiniceae | + | |
Tamarindus indica (L.) | Caesalpiniceae | + | + |
Albizia lebbeck (L.) Benth | Fabaceae | + | + |
Senna siamea (ex cassiasiamea) | Fabaceae | + | |
Daniella oliveri (R.) Hutch & Dalz | Meliaceae | + | |
Acacia nilotica (L.) Wildvar. Adansonii (L.) | Mimosaceae | + | + |
Acacia sieberiana (D.C) | Mimosaceae | + | + |
Dichrostachys cinerea (L.) Wight et Arn. | Mimosaceae | + | + |
Prosopis juliflora (Sw.) DC., | Mimosaceae | + | + |
Faidherbia albida (Chev.) | Mimosaceae; | + | |
Prosopis africana (G. & Perr.) | Mimosaceae; | + | + |
Arachis hypogaea (L.) | Papilionaceae | + | + |
+: Present in the zone.
zone. In the family of Mimosaceae, six plant species were collected: Acacia nilotica var. adansonii (
The fruits collected in the different geographical areas of the country and under observation allowed to obtain adults (
In the southern Sudanese zone (
Analysis of the results (
In Karangasso Sambla (
The inventory of Caryedon carried out in the different agro-ecological zones showed that only two species was identified and our results confirm the presence of two species of Caryedon distributed throughout the Burlkina Faso. These species were found in the whole of the agro-systems of Burkina Faso with a clear prevalence for C. serratus species. Its presence in all the prospected sites is explained by a homogeneous distribution of its host plants. In fact, on the faunistic inventory carried out, six host plants are well-distributed on the whole country allowing the development of the populations of C. serratus. Thus in the Sahelian
zone of Dori, C. serratus was found on B. rufescens, a perennial plant that can live and develop in arid regions where the pluviometry is bellow 600 mm. This situation represents an adaptation of this plant species which was also found in wet zones as in Congo Brazaville [
During groundnut storage, several groups of insects associated to this crop during were found that confirms the observations which report that groundnut is attacked by several groups of insects at the time of storage among which C. serratus, E. cautella, P. interpunctella and T. castaneum [
The low number of C. crampelli species is related to the reduced number of its host plants whose geographical distribution is not always homogeneous. It is the case of P. africana main host plant of C. crampelii. The important use of the pods of this plant in animal feed led to the scarcity of its pods and thus of C. crampelii in some areas. The identified species of Caryedon differ from those identified by other authors [
The plants play an important role in the development of the beetle like the species Caryedon. Indeed, the presence of P. thonningii and T. indica constitute sources of infestation in groundnut in Congo and Senegal [
The host plants which ensure the survival and distribution of bruchidae in Burkina Faso are favorable to the evolution of these insects. The absence of secondary substances in these plants unfavorable to the evolution of the larvae of these insects that explain the preference of these plants by these insects [
As for groundnut, very little research work on the losses caused by C. serratus in farming areas on this leguminous plant is available apart from those reported in Congo Brazaville [
In fact, in Congo Brazaville, P. thonningiiis one of the sources of infestation of groundnut stocks [
The inventory work carried out in the agro-ecological zones of the country has permitted to identify the presence of two species of Caryedon which are C. serratus and C. crampelii. Studies on the geographical distribution of these species indicate that they are present in various agricultural zones of Burkina Faso. C. serratus is the widely spread species; it was found in all the agro-ecological zones of the country. In the western zone of Burkina Faso, the checking of groundnut stocks showed that only C. serratus infests groundnut stocks. The laying and nutrition activities of the larvae of C. serratus in groundnut stocks are at the basis of the perforation of groundnut pods which can reach 70% without any protection methods. The importance of the damage observed in groundnut stocks is explained by the presence of old stocks of groundnut “infested with beetles” but also by the gathering and conservation of some wild fruits such as the pods of T. indica and P. thonningii which generally are infested by C. serratus and which constitute sources of infestation of groundnut stocks. The results showed us the mode of infestation of groundnut stocks in the rural areas of Burkina Faso and this study can foster ways and means for the reduction of the perforations of groundnut pods related to the presence of C. serratus.
This work was achieved thanks to the financial support of the International Foundation for Science (IFS).
Authors have declared that no competing interests exist.
Ouedraogo, I., Sembene, M. and Dakouo, D. (2017) Inventory, Geographical Distribution of Caryedon Species in Burkina Faso, and Evaluation of Their Impact on Stored Groundnut. Advances in Entomology, 5, 55-67. https://doi.org/10.4236/ae.2017.52005