International Journal of Tropical Insect Science

Research Article

Effect of Anisopteromalus calandrae (Hymenoptera: Pteromalidae) in controlling residual populations of Rhyzopertha dominica (Coleoptera: Bostrichidae) in wheat stores

N. Mahala1, W. Islama2 c1, S. Parweena2 and K.A.M.S.H. Mondala1

a1 Department of Zoology, New Govt Degree College, Rajshahi, 6000, Bangladesh

a2 Institute of Biological Sciences, University of Rajshahi, Rajshahi, 6205, Bangladesh

Abstract

The parasitic wasp Anisopteromalus calandrae (Howard) was released at six (5, 10, 20, 30, 40 and 50 pairs) densities to evaluate the effects of different introduction rates in controlling residual populations of the lesser grain borer Rhyzopertha dominica (Fabricius) in wheat grain stored in bulk in 46 m2 rooms. At the 50-pair density, the parasitoid suppressed 83% of R. dominica in June–July and 74% in August–September. At the 5-pair density, the numbers of F1 progeny per female were 44 and 51, during the first and second period, respectively while at the 50-pair release rate, only 6 and 7 individuals were recorded, respectively. In a second test, the effects of different materials used for storing were evaluated on both insects. Five hundred (500) grain-residing 20–22-day-old R. dominica larvae were mixed with 250g fresh wheat stored separately in each of five types of bags, i.e. jute, calico (Americana cloth), polypropylene, polythene, nylon, then exposed to 50 pairs of A. calandrae. The parasitoid suppressed host populations in all types of bags, except in those made of polythene. The highest percentage (69 and 81%) suppression occurred in calico bags during the June–July and August–September periods, respectively. The lowest suppression of 51 and 57% was observed for polypropylene bags during the respective periods. The parasitoid-induced mortality was positively correlated with the parasitoid density.

(Accepted March 22 2005)

Correspondence

c1 *: Email: mwislam2001@yahoo.com

0Comments