Development and Life-Fertility Tables for Diatraea lineolata (Lepidoptera: Pyralidae) at Constant Temperatures

Development, survival, and reproduction of Diatraea lineolata (Walker) were characterized at 22, 25, 28, and 31°C constant temperatures. Developmental times were inversely related to temperature; egg-to-adult duration decreased from 65 d at 22°C to 39 d at 31°C. Egg-to-adult developmental time was longer for females than for males only at 28 and 31°C (P < 0.05). Egg-to-adult development of D. lineolata males and females was 3.2 d longer on artificial diet than on field corn at 25°C (P < 0.05). Larval development was completed in five, six, or seven stadia; however, <75% of the individuals completed six larval stadia regardless of temperature, diet, and sex. Females exhibited a greater number of stadia than males only at 22 and 31°C (P < 0.05). A good linear model fit (R2 > 0.840) between developmental rate (y) and temperature (x) was observed for all D. lineolata stages. The lower developmental threshold was estimated at 8.5°C for egg-to-adult development and ranged from 5.2° (sixth instar) to 12.5°C (egg stage). Degree-days (above 8.5°C) required by D. lineolata males and females to complete the egg, larval, pupal, and egg-to-adult stages were 106, 563, 199, and 868, respectively. Fecundity, egg viability, oviposition period, and adult longevity were reduced with increasing temperature. The reproductive performance of D. lineolata was similar for females reared on either artificial diet or field corn. Age-specific life-fertility tables and survivorship curves were constructed for all cohorts (temperatures and diets). Although differences in egg mortality were attributed to temperature, larval and pupal mortality differences were caused only by diet. Population reproductive statistics (R0, Tc, rc, λc) were estimated from the life-fertility tables. The capacity for increase peaked at 25°C (rc = 0.054 females per female per day). The relation of these results to other crambine stalkborer species is discussed.