Effects of temperature and parasitoids on the growth and development of Spodoptera frugiperda
Abstract:
[Aim] To investigate
the impact of temperature and the parasitoid Microplitis pallidipes on
the growth and development of Spodoptera frugiperda, thereby assessing
the potential of using M. pallidipes as a biological control for this
pest. [Methods] The body length,
head width, body weight and food intake of S. frugiperda larvae raised at
temperatures of 14, 20, 26, and 32 ℃ were measured using vernier calipers and an electronic
balance, and the effects of temperature and parasitism on the growth rate and
survival of S. frugiperda larvae were analyzed. [Results] Our findings indicate that both temperature
and parasite infestation significantly affected the body length, head width,
weight, and food intake, of S. frugiperda larvae. Unparasitized
larvae raised at 32 ℃ had
1.76 times the body length, 1.68 times the head width, 7.29 times the
weight, and consumed 14.25 times more food, than those in the parasitized
treatment group at the same temperature. They were also 2.85 times the body
length, 2.77 times the head width, 19.96 times the body weight, and consumed
19.90 times more food, than those raised at 14 ℃ without parasitism, and had 3.30 times
the body length, 3.08 times the head width, 34.70 times
the weight, and consumed 106.38 times as much food, than those raised at 14 ℃ with parasitism. The body length, head
width, and body weight, of unparasitized larvae were all greater than those of
parasitized larvae at all four temperatures. The highest growth rate was
observed in unparasitized larvae raised at 32 ℃, and the lowest in parasitized larvae
raised at 14 ℃. The
mortality rate of parasitized larvae was also significantly higher than that of
non-parasitized larvae under all four temperatures (P<0.05).
Furthermore, the mortality rate of non-parasitized larvae decreased with
increasing temperature, whereas the larval stage of non-parasitized larvae and
the survival time of parasitized larvae decreased with increasing temperature.
[Conclusion] These findings
suggest that M. pallidipes inhibits the growth, development and survival
of S. frugiperda at temperatures between 14 and 32 ℃, and that the
degree of inhibition varies with temperature.