Life table studies of Helicoverpa armigera (Hübner) in tomato
Loading...
Date
2019
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Punjab Agricultural University, Ludhiana
Abstract
Life table studies of Helicoverpa armigera (Hübner) were carried out in tomato with respect to its biology and life tables under field and laboratory conditions during 2018 and 2019. The duration of different developmental stages of H. armigera was maximum in main season crop and minimum in spring season crop. As compared to the spring season crop, main season crop was more favourable for the development and reproduction of H. armigera. The maximum growth index was observed in main season crop (2.55±0.26) as compared to spring season crop (1.42±0.10) which indicated that H. armigera grew well on main season crop. The life table studies under field conditions in main and spring season crop revealed that in main season crop, highest mortality occurred in early larval instar stage followed by late larval instar stage, egg stage and pupal stage whereas, in spring season crop, egg stage was found to be the most vulnerable/susceptible stage due to various abiotic factors. Egg inviability, natural enemies and unknown factors were responsible for reduction in H. armigera population under natural conditions. The studies on effect of different alternating temperatures on biology and life table parameters of H. armigera on tomato revealed that the duration of different developmental stages of H. armigera decreased with increase in alternating temperature from 28:15°C to 36:18°C, resulting in shorter life cycle at higher temperatures. The fecundity of females varied from 166.83±3.31 to 557.49±5.17 eggs per female at different alternating temperatures. The highest intrinsic rate of increase (rm) of H. armigera was reported at 28:15oC (0.0764) and 28:18oC (0.0777), whereas lowest was at 36:18oC (0.0560). The net reproductive rate was maximum at 28:15oC (58.35) and minimum at 36:18oC (5.77). On the basis of tested alternating temperature combinations, 28:15oC and 28:18oC at 70±5 per cent relative humidity. were found to be the most favourable conditions for the growth and development of H. armigera.
Description
Keywords
null