Abstract:

【Aim】To clarify the impact of humidity change on the growth, development and fecundity of Tuta absoluta.【Methods】At the relative humidities of 15%, 35%, 55%, 75% and 95% indoor, the developmental parameters including developmental duration, pre-oviposition period, generation time, larval survival rate, adult survival rate, and number of eggs laid per female of T. absoluta were measured. The age-stage, two-sex life table s of T. absoluta were constructed, and population parameters including survival rate, fecundity, life expectancy, and reproduction value were calculated using the age-stage, two-sex life table.【Results】At the relative humidities of 15%－95%, the egg duration at the relative humidity of 15% and 95% were significantly longer than those at the relative humidities of 35%, 55%, and 75%. The 4th instar larval duration first shortened and then lengthened with the relative humidity increased. The male adult longevity increased with the rising relative humidity, reaching the maximum at  the relative humidity of 95%. The female adult longevity was the longest at the relative humidity of 75%. The generation time was significantly longer at relative humidity of 95% than those at other relative humidities. The number of eggs laid per female increased with the increasing relative humidity. The initial oviposition time of female adults was affected by the relative humidity, the initial oviposition time were 31, 27, 27, 27 and 31 d at the relative humidities of 15%, 35%, 55%, 75% and 95%, respectively. The population age specific net maternity and age-stage-specific reproductive value increased with the rising relative humidity, reaching the maximum at the relative humidity of 95%. The intrinsic rate of increase and finite rate of increase initially increased and then decreased with the rising relative humidity, the net reproductive rate increased with the rising relative humidity. The mean generation time initially decreased and then increased with the rising relative humidity. According to the parameters of the population life table, the prediction of population dynamics within next 60 d indicated that the relative humidity of 95% was conducive to the increase of population size, relative humidities of 15% and 95% were unfavorable to the increase of the population generation number. The impacts of different relative humidities on the survival rates of eggs and larvae were significant through linear regression fitting. 【Conclusion】Within the test setting relative humidity range, the optimal relative humidities for the growth and development of T. absoluta are 55% and 75%, and the optimum relative humidity for reproduction are 95%.

Key words: Tuta absoluta, relative humidity, age-stage, two-sex life table, growth and development, reproduction