BIONOMICS OF A DESERT COCKROACH, HETEROGAMISCA-CHOPARDI UVAROV, 1936 AFTER THE SPRING RAINFALLS IN SAUDI-ARABIA (INSECTA, BLATTARIA, POLYPHAGINAE)

The habitat choice and population structure of Heterogamisca chopardi were studied in a middle altitude desert of Saudi Arabia (30 km east o f Taif) during June 1992. Two populations were compared, located, resp ectively, in a 3-year-old protected area and in a grazed area. Cockroa ches live in the sand beneath shrubs. They preferred shrub species acc ording to their cushion form, possibly depending on grazing pressure. Population densities ranged between 0.25 and 0.42 individuals per m(2) . Most individuals in June were middle-instar nymphs, with few first-i nstar nymphs and old females. Oothecae were frequently parasitized by Aies (Bombyliidae). In comparison with the protected area, the grazed area showed higher density, the presence of younger middle-instar nymp hs and of old females, higher fecundity, larger oothecae, a sex ratio less biased towards females, and probably lower nymphal survival. (C) 1995 Academic Press Limited