Effect of Constant Temperatures on Biological Parameters of Tuta absoluta (Meyrick, 1917) on Tomato Plants in Case of Asexual Reproduction (Parthenogenesis

Abstract

Tomato leafminer Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) is a key devastating pest worldwide, it has the capacity to develop on a wide range of Solanaceous plants but tomato (Solanum lycopersicum L.) is considered to be its preferred host. This study was carried out at the Agricultural Scientific Research Centre in Latakia in 2019 to estimate biological parameters of T. absoluta and evaluate the effect of temperature in its development, longevity, reproduction in parthenogenesis. The experiments were carried out at constant temperatures (10, 20, 30˚ C), 60-65% RH, and photoperiod (16L: 8D). Biological parameters were analyzed according to the theory of age-stage two-sex life table by using the computer program TWO-SEX MSchart. The highest value of intrinsic rate of increase (r), the final increase rate (λ), and net reproductive rate (Ro) were 0.0439±0.0028 females/female/day, 1.0449±0.0029, and 7.01±0.8705 females/female/generation, respectively, at 20˚C. The lowest value of net reproductive rate (Ro) was 0.92±0.1250 females/female/generation at 30˚C. Generation time (T) was the longest (44.3±0.203 days) at 20˚C and decreased to 26.38±1.156 days at 30˚C. T. absoluta completed its development at all these temperatures. The results obtained showed that the effect of temperature on the insect development from egg to adult decreased with increased temperature. The shortest development period on egg, larva and pupa development was 3.95±0.149, 11.975±0.075 and 4.95±0.086 days, respectively, at 30˚C. This means that the development time from egg to adult was shorter (20.8±1.151 days) at 30˚C as compared to 34.51±0.127 days at 20˚C, and longest at 10˚C (125.4±1.211 days). The female longevity was longer (61.35±0.25 days) at 20˚C. The highest rate of fecundity was 12.98±1.072 eggs/unmated female, and the lowest was 2.19±0.152 eggs/unmated female at 30˚C. Moreover, the unmated females kept at 10˚C did not lay eggs, and unfertilized eggs (asexually produced eggs) laid by unmated females at 20 or 30˚C did not hatch. The adult pre-oviposition period (APOP) of unmated females was 2.57±0.1368 days at 20˚C and 4.31±0.2629 days at 30˚C, whereas the total APOP of females was 36.86±0.1844 days at 20˚C and 24.21±0.3039 days at 30˚C. Keywords: Tomato leaf miner, Life tables, asexual reproduction, Parthenogenesis, Syria