Effects of exposing differential developmental stages to short-term cold on the survival and reproduction of Plutella xylostella
Author of the article:CUI Rui-Yuan;MA Jia-Qi;JIN Bo;XU Hao-Tian;LI Ting;HU Jun-Hua;JIA Li;YAN Xia;LI Bo-Liao;XU Shi-Cai
Author's Workplace:College of Life Science, Yan’an University; Shaanxi Engineering and Technological Research Center for Conversation and Utilization of Regional Biological Resources, Yan’an 716000, China;College of Life Science, Yan’an University; Shaanxi Engineering and Technological Research Center for Conversation and Utilization of Regional Biological Resources, Yan’an 716000, China;College of Life Science, Yan’an University; Shaanxi Engineering and Technological Research Center for Conversation and Utilization of Regional Biological Resources, Yan’an 716000, China;
Key Words:vegetable pest; short-term cold stress; developmental stage; survival curves; reproductive parameters
Abstract:
[Objectives] To investigate the effects of exposing
different developmental stages of Plutella
xylostella to different durations of low temperature on the survival and
reproductive capacity of this species, thereby providing a reference for
predicting and preventing the occurrence of this pest in greenhouses in winter. [Methods] The pupation rate, eclosion rate, adult
lifespan, adult pre-oviposition period, oviposition period, and fecundity per
female of P. xylostella were recorded under laboratory conditions of
55%±10% relative humidity and a 12L∶12D light cycle. Fourth instar larvae, pupae and
adults were exposed to 8 °C for 24, 48 and 96 h. A control group was kept at
(26±1)℃. [Results] Irrespective of the duration, cold
exposure did not significantly change the pupation rate of P. xylostella (χ2 = 1.58, P =
0.664). However, development stage (χ2 = 202.52, P < 0.001) and the duration of cold
treatment (χ2 = 141.83, P < 0.001) significantly affected the
emergence rate. The effect of cold exposure on the emergence rate was higher
for 4th instar larvae than for pupae (4th larval instar: 0.874 0; pupal stage: 0.669 7). Adult lifespan
was affected by both the duration of cold exposure (χ2 = 39.3, P < 0.001) and developmental stage (χ2 =
141.83, P < 0.001). Within a
certain range, the duration 4th instar larvae were exposed to cold had no
significant effect on the life span of male and female adults (females: χ2= 41.86, df =
3, P = 0.330;males: χ2 = 4.55, df = 3, P = 0.210),
whereas the effect of cold exposure on the life span of both sexes was increased
by the duration of cold exposure during the pupal stage (females: χ2 = 41.86, df =
3, P < 0.001; males: χ2 = 14.30, df = 3, P < 0.001). The longevity of adult males was also increased by
increasing the duration of cold exposure (χ2 = 19.32, df = 3, P < 0.001). Male adults generally
lived longer than female adults (immature stage: χ2=﹣3.88, P < 0.001; adult
stage: χ2 =﹣5.72, P <
0.001). The adult pre-oviposition period was prolonged by increasing the
duration of cold exposure (immature stage: χ2 = 14.40, df = 3, P = 0.002; adult
stage: χ2= 60.04, df =
2, P < 0.001). With the exception
of pupae exposed to cold for 96 h (40.9 eggs/female), the average female
fecundity in other treatment groups did not significantly decrease compared to
the control group (87.3 eggs/female). [Conclusion] Exposing the pupae of P.
xylostella to 8 ℃ had a greater impact on subsequent survival and
oviposition than exposing fourth larval instar. The reduction in survival and
reproduction increased with the duration of exposure to low temperature.