The effect of the dry and wet seasons on chiasma frequency in male Taphronota thaelephora Stal. 1873 and Zonocerus variegatus L. 1753 (Orthoptera: Pyrgomorphidae) in Cameroon

A study of the male meiotic systems in dry and wet season populations of the African pest grasshoppersnTaphronota thaelephora and Zonocerus variegatus (Orthoptera: Pyrgomorphidae) was carried out. Data obtained revealed that mean chiasma frequency was significantly higher in the dry than wet season populations of these species. However, Duncan Multiple Range Test revealed that mean chiasma frequency was not significantly different (P>0.05) between dry and wet season populations of T. thaelephora but was significantly higher (P<0.05) in the dry than wet season populations of Z. variegatus. Differences in the number of rod and ring shaped bivalents in Diplotene were not consistent in the dry and wet season populations of both species nor were the number of bivalents with 1, 2 and 3 chiasmata. These results indicated that this environmental cue is not responsible for the observed differences in chiasma frequency in these pest species.