Life hystory and bionomics of the argentine cotton-stainer Dysdercus chaquensis Freiberg, 1948 (Heteroptera: Pyrrhocoridae).

T. STADLER; M.M. SCHANG; M.E. LATTUCA; J. DIZ

Isla Margarita, estado de Nueva Esparta, Venezuela.

Congreso; V Congreso Latinoamericano XIII Venezolano de Entomología; 1993

Sociedad Venezolana de Entomología, Universidad Central de Venezuela.

Various aspects of the life cycle and natural history are summarized for the “cotton-stainer” D. chaquensis studied in laboratory conditions and in selected localities from salta-Argentina. The life cycle of D. chaquensis, reared on cotton seeds at 26ºC ± 3ºC and 80% ±5% HR, evolve in 42 days (STD= 2,66). The egg hatches in 4,63 (STD= 0,76) days and the average time in days for development of the different nymphal instars is: NI 2,76 (STD= 0,88); NII 7,66 (STD= 2,49); NIII 5,20 (STD= 2,19); NIV 6,64 (STD= 2,23); NV 10,04 (STD= 2,79). A one day interval mediate between the last moult and copula and the time span from copula to first oviposition is 4,12 (STD= 1,15) days. A female oviposits up to four times (X= 1,96; STD= 0,92), producing an average number of 100 eggs during the bulk of her lifetime; moreover the average number of eggs per oviposition is quite variable (X= 54,04, STD= 0,92, Xmin= 15 – Xmax= 103). The eggs were lied in loose clusters at 1 cm to 2 cm deep in soil splits and the selection of oviposition sites depends on several ecological factors like soil moisture and presence of food plants. D. chaquensis is polivoltine and field populations in NW-Argentina evolve from September to May due to overlapping of host-plant flowering. Up to now, three species of natural hosts-plants were identified: two Malvaceae (Wissadula densiflora and Spharalcea bonaerensis) and an Euphorbiaceae (Julocroton argenteus).