International Journal of Applied Research
Vol. 3, Issue 11, Part G (2017)
Developmental ecology of sorghum chafer (P. interrupta Oliver, Coleoptera: Scarabaeidae) amid diverse physical and biological factors
Ethiopia is primarily an agrarian based economy with rich fertile lands with ancient type of agricultural farming systems. Among various agricultural products Sorghum [Sorghum bicolor
(L) Moench] is an extremely important staple food in Ethiopia. The sorghum production however, is threatened by a wide range of both pre and post-harvest pests of which the sorghum chafer, Pachnoda interrupta
(Oliver) (Coleoptera: Scarabaeidae) cause much damage due to lack of successful control methods.
Present work is the laboratory study report supported with field observations made to understand the life cycle and development of Pachnoda interrupta (Oliver), along with its interaction on impact of physical factors and soil types on its development. Soil samples collected from Afar, Tikur-Inchini and sandy soil from Guder River near Ambo were used separately and mixed with different proportion of cow-dung. Eight types of food substances were tested for their effect as bait in the infested area. In the life cycle study (at 25 ˚C & Moisture 17%) the average oviposition rate was found to be 0.58 eggs/ day/ female. Whitish soft shelled eggs were laid separately in soil varying (strata) from 3-18 cm. in depth. The mean number of days for egg hatching was 9.63±1.4 ranging between 8 and 13. Larval development took an average of 59.09± 1.94 days ranging between 42-73. Body length was constantly increasing up to around 52 days where it reached 30.2 mm and was shrinking to its last days and measured 28mm at about the 70th days. Larval head capsule width however showed discontinuous but constant increase and at an average 3.14+0.01mm was measured in final days (62-70). Papal development ranged from 18-30 days with an average of 24.47 ±3.5 days. When soil moisture is less the larvae went down deep in to the soil to pupate and when it is high, they remained in the upper layers. Soil temperature however did not show significant effect on pupation depth. The adults required an average of 93.79± 1.8 days, ranging from 68-116 to emerge.
The laboratory study and the field observation confirmed that P. interrupta are univoltine insects having two phases in their life cycle (emerging seasons). The presence of cow-dung in the soil was found necessary for the completion of life cycle in P. interrupta.
How to cite this article:
Gabeyehu Feleke. Developmental ecology of sorghum chafer (P. interrupta Oliver, Coleoptera: Scarabaeidae) amid diverse physical and biological factors. International Journal of Applied Research. 2017; 3(11): 437-441.