Abstract

ARRIECHE, Norayda; PAZ, Ramón; MONTAGNE, Aquiles  and  MORALES, José. Biological studies of Thrips tabaci Lindeman (Thysanoptera: Thripidae) from onion fields, Lara State, Venezuela. Bioagro [online]. 2006, vol.18, n.3, pp.149-154. ISSN 1316-3361.

Studies were conducted to gain new understanding on the biology of the insect pest, Thrips tabaci Lindeman, using onion as the host plant. Onion leaves infested with thrips were obtained during years 2000 and 2001 in a farm located in Quíbor, Lara State, Venezuela. In the laboratory, individually caged Texas Grain 438 onion plants were infested with five adult thrips per plant. Findings were as follow: the average development time of T. tabaci from egg to adult lasted 14.2 ± 1.7 days (egg = 3.2 ± 0.52; larvae I = 2.7 ± 0.21; larvae II = 2.9 ± 0.18; prepupae 1.9 ± 0.33; pupae = 3.5 ± 0.45 days). Average values for preoviposition, oviposition and postoviposition were 2.0, 8.0 and 2.0 days, respectively, while the average egg number laid per female during its life was 39 ± 10.5. The average adult female longevity was 11.5 ± 1.8 days. Thrips sex ratio progeny revealed no presence of males, since only females emerged. The elliptical eggs are white with average values of 0.22 ± 0.05 mm long and 0.1 ± 0.4 mm wide. First instar larvae were from white to yellow pale with values of 0.45 ± 0.1 mm long, while second instar larvae were from yellow to brown with average values of 1.1 ± 1 mm in length. The prepupae were yellow with average values of 0.81 ± 0.2 mm in length, while pupae were from pale yellow to brown with average values of 0.95 ± 0.2 mm. The adult stage was pale yellow to dark brown with average values of 1.4 ± 0.2 mm in length. Knowledge on this insect pest biology will allow establishing control strategies in a future integrated pest management program.

Keywords : Pests; eggs; longevity; developmental stage; IPM.