Effect of temperature on reproduction parameters of potato tuberworm, Phthorimaea operculella (Lepidoptera: Gelechiidae)

The potato tuberworm, Phthorimaea operculella (Zeller), is the most destructive pest of potato crops (Solanum tuberosum L.) worldwide, especially in tropical and subtropical zones. The larvae attack foliage and tubers in the fields and in storages. The development and reproduction of the potato tuberworm is strongly influenced by temperature as a key climatic factor. Reproduction parameters of P. operculella were studied at six constant temperatures (16, 20, 24, 28, 32 and 36ºC), 65±5% RH and a photoperiod of 8:16 (L:D) hours on potato tuber. The population failed to survive at 36ºC. All measured parameters were significantly were significantly affected by temperature. The egg hatching rates varied from 0.71 to 0.91 at 32 and 24 ºC, respectively. The gross fecundity rate ranged from 46.1±10.0 at 16ºC to 133.8±19.7 at 24ºC. The gross fertility rate had similar variation and varied from 38.3±8.3 at 16ºC to 121.3±17.8 at 24ºC. The net fecundity and fertility rates were increased with increasing temperature up 28°C and the decreased at 32°C. The highest value of net fecundity and fertility rates were 82.8±10.3 and 72.1±9.0 at 28°C, respectively. The lowest value of both related parameters was observed at 16°C. The number of eggs laid by female per day was ranged from 2.8±0.6 at 16°C to 17.5±2.2 at 28°C. Moreover, the mean number of fertile eggs per female per day was ranged 2.3±0.5 at 16°C to 15.2±1.9 at 28°C. These findings could be considered in pest management program for potato tuberworm in potato fields and storerooms.