STUDIES ON BIOLOGY OF PHENACOCCUS SOLENOPSIS TINSLEY (HEMIPTERA: PSEUDOCOCCIDAE) IN PUNJAB, PAKISTAN - A PEST OF COTTON AND OTHER CROPS

An introduced species of mealybug (Hemiptera: Pseudococcidae) severely damaging cotton (Gossypium hirsutum L.) was found in Pakistan in 2005. Phenacoccus solenopsis Tinsley is highly polyphagous and is considered to be a potentially invasive pest for many economic crops throughout the tropics and subtropics. Biology of P. solenopsis, was undertaken at the University of Faisalabad, Pakistan, where laboratory cultures were kept at 25±2°C and 65±5% relative humidity on excised leaf-discs. Mortality was highest (75%) in the first and (20%) second instars; after the second instar, the paedomorphic female s normal lifespan (hatching to death) was 16-43 (mode 38) days. Female developmental stages had the following mean durations (in days): first instar 6.8, second instar 6.4, third instar 7.3, adult 4.6 days. Mean developmental stage durations for the winged male were: first instar 6.8, second instar 6.4, “prepupa” + “pupa” (in cocoon) 5.0, adult 2.2, with a total lifespan cumulative average (hatching to death) 16.0 days. Females were probably ovoviviparous, each producing an average of 2.6 crawler sacs; the mean number of crawlers produced per female was 77.9. Successful reproduction is through mating of male and females. The male: female sex ratio studied in the laboratory and field conditions cumulatively remained 1:1.29 which was not significantly different between laboratory and field populations, or between populations on three different host plants.