Inventory and Distribution of Mango Mealybugs Species in Western Burkina Faso: Relative Abundance and Population Fluctuation

Rastrococus invadens was the only reported mealybug species on the mango tree in Western Burkina Faso. This study aimed at carrying out the inventory and showing the importance and distribution of other mealybug species associated with the mango tree. It was also important to determine the periods of abundance of these species vis-a-vis R. invadens. For this purpose, the density of mealybugs was assessed in three study sites (Toussiana, Bérégadougou and Orodara) in Western Burkina Faso. The observations were made from June 2014 to June 2015 at a frequency of 15 ± 1 days. They focused on 20 leaves (5 leaves/cardinal point) levied on each mango tree. The species identified as Ferrisia virgata Cockerell and Icerya aegyptiaca Douglas were collected from mangos infested by R. invadens representing 98% - 99% of the density of the observed mealybug species. The periods of abundance of F. virgata and I. aegyptiaca were respectively the dry season and the rainy season. The effect of temperature, relative humidity and rainfall on the populations of F. virgata and I. aegyptiaca was also discussed. These results highlight the distribution range of F. virgata and I. aegyptiaca worldwide including Burkina Faso. R. invadens was the main mealybug species on mango in Burkina Faso in general and in the Western region of the country in particular.

Inventory and Distribution of Mango Mealybugs Species in Western Burkina Faso: Relative Abundance and Population Fluctuation

Rastrococus invadens was the only reported mealybug species on the mango tree in Western Burkina Faso. This study aimed at carrying out the inventory and showing the importance and distribution of other mealybug species associated with the mango tree. It was also important to determine the periods of abundance of these species vis-a-vis R. invadens. For this purpose, the density of mealybugs was assessed in three study sites (Toussiana, Bérégadougou and Orodara) in Western Burkina Faso. The observations were made from June 2014 to June 2015 at a frequency of 15 ± 1 days. They focused on 20 leaves (5 leaves/cardinal point) levied on each mango tree. The species identified as Ferrisia virgata Cockerell and Icerya aegyptiaca Douglas were collected from mangos infested by R. invadens representing 98% - 99% of the density of the observed mealybug species. The periods of abundance of F. virgata and I. aegyptiaca were respectively the dry season and the rainy season. The effect of temperature, relative humidity and rainfall on the populations of F. virgata and I. aegyptiaca was also discussed. These results highlight the distribution range of F. virgata and I. aegyptiaca worldwide including Burkina Faso. R. invadens was the main mealybug species on mango in Burkina Faso in general and in the Western region of the country in particular.

Incidence of the African Rice Gall Midge (AfRGM), Orseolia oryzivora H. &G. in Relation with Period of Rice Transplanting in the Kou Valley, Burkina Faso

The African Rice Gall Midge, Orseolia oryzivora H. & G., is an important insect pest recorded in 20 countries in Sub-Sahara Africa. In Burkina Faso, the insect pest particularly prevails in Western and South-Western of the country where both biotic and abiotic conditions favor its development. The insect pest can damage up to 60% of rice tillers in Western Burkina Faso. A study was conducted during the 2011 wet season in the Kou Valley, located 25 km North-West of Bobo-Dioulas- so, Western Burkina Faso. Its objective was to evaluate the damage of this insect pest in farmers’ fields in relation with rice transplanting periods. The Kou Valley rice scheme, 1200 ha, was divided into two zones within which 48 farmers’ fields were randomly selected in relation with rice transplanting periods: P1: 1st period;P2: 2nd period and P3: 3rd period;that is 16 fields per period. Both agronomic and entomological evaluations were performed each week starting from the 21th day after transplanting (DAT) up to 84 DAT. Results showed that the highest average damage level (16% of galls) was recorded in the 3rd transplanting period. The highest larval and pupal parasitism was recorded in P3 at 84 DAT. Pupal parasitism due to Aprostocetus procerae Risbec was higher than larval parasitism due to Platygaster diplosisae Risbec. Lastly, the lowest yield (4.78 t/ha) was recorded in P3. These results can be used in the implementation of an integrated pest management strategy for this insect pest in the Kou Valley.

Inventory, Geographical Distribution of <i>Caryedon</i>Species in Burkina Faso, and Evaluation of Their Impact on Stored Groundnut

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.

Influence of Host Plants on the Development of Caryedon serratus Olivier (Coleoptera: Chrysomelidae, Bruchinae), Insect Pest of Groundnut Stocks in Burkina Faso

The beetle Caryedon serratusOlivier is a major insect pest responsible for the infesta-tion and damage on groundnut during storage. To understand the infestation mecha-nism of groundnut stocks, studies have been carried out on this insect biology under laboratory conditions in relation with its host plants. The results have demonstrated that the pre-oviposition on groundnut lasts on average 1.28 days. The oviposition pe-riod is 12.04 days, during which 80.42 eggs on average are laid. From hatching to adult stage, C. serratus larvae development goes through four stages with variable durations according to the stage. Three families of host plants (Papilionaceae;Caesalpiniaceae and Mimosaceae) were selected for females C. serratusto lay on their seeds. The re-sults showed that more eggs were laid on the seeds of Papilionaceae (98.75% of in-fested seeds) followed by Caesalpiniaceae (28.59% of infested seeds). Studies were carried out on the laying behavior of C. serratus under laboratory conditions and have revealed that whatever the conditions, C. serratus females lay on all the plant species seeds exposed. Insects’ development duration has varied according to the plant species seeds used.