Effect of temperature on development, survival and reproduction of the mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) on cotton

The effect of temperature on life cycle of the solenopsis mealybug, Phenacoccus solenopsis Tinsley, on cotton (Gossypium hirsutum L.) was assessed under laboratory conditions at ten constant temperatures (18–40 °C). The development duration of female and male nymphal instars linearly decreased with the increase in temperature from 18 to 32 °C. Cumulative developmental time of females ranged from 43.9 d (18 °C) to 15.0 d (32 °C). Survival of crawlers to adulthood was lowest (<53%) at 20 and 36 °C and highest (80%) at 32 °C. The solenopsis mealybug exhibited obligate sexual ovoviviparous reproduction and the pre-oviposition period in mated females showed a significant decreasing trend between 20 °C (23.0 d) and 30 °C (9.5 d). The oviposition period of 10.2–11.5 d at ≥25 °C was nearly half the duration than at 20 °C and the highest fecundity (245 eggs + crawlers) was observed at 30 °C. Longevity of mated females was significantly prolonged at 20 °C (46.0 d) compared to 30 °C (21.4 d). Proportion of females was highest (97.5%) at 25 °C. Males required higher degree-days (363.6) for their cumulative development compared to females (317.5). Lower temperature thresholds estimated from the linear model for cumulative female and male development were 11.7 and 10.1 °C, respectively. The estimated optimum temperature thresholds for nymphal instars (32–33.4 °C) from β type distribution function were closer to the observed maximum developmental rate compared to Lactin-2 model. The population trend index using survival, fecundity, and sex ratio of P. solenopsis with an initial population of 100 crawlers in the Morris-Watt life table model indicated a potential population increase of 170.3 and 97.6 times at 30 and 35 °C, respectively, in the next generation. The usefulness of the information on the temperature-dependent life cycle of P. solenopsis in understanding its field abundance and distribution on cotton and implications for management is discussed.

► Obligate sexual ovoviviparous reproduction observed with highest fecundity at 30 °C.
► For total ♀ development, Tmin, Topt & Tmax were 11.7, 32.3 & 39 °C, respectively.
► Males required higher degree days (363.6) for total development than females (317.5).
► Survival of crawlers to adults lowest at 20 & 36 °C (<53%) & highest at 32 °C (80%).