Biology, life table and predatory potential of the green lacewing, Chrysoperla zastrowi sillemi (Neuroptera: Chrysopidae) on tea red spider mite, Oligonychus coffeae (Acari: Tetranychidae)
摘要
The tea red spider mite Oligonychus coffeae, is considered as important dry weather pest which accounts for almost 8–17% crop loss in South Indian tea plantations. The green lacewing Chrysoperla zastrowi sillemi is one of the prominent predators of soft bodied insects of different agro-ecosystems, including tea. However, the data on biology and life table parameters of this predator on tea red spider mite are limited and hence the current study was undertaken on the biology and life table parameters of C. z. sillemi at three temperature regimes (20 °C, 25 °C and 30 °C) under laboratory conditions. Furthermore, its biocontrol potential was evaluated under field conditions for two seasons. During the study, the eggs, larvae and adults were collected from UPASI Experimental Farm and the taxonomic determination was ascertained through COI gene sequencing. The biological parameters such as duration of oviposition, mean fecundity, percentage hatchability of eggs, duration of larval development and longevity of adults were significantly optimum at 20 °C, among the three temperature regimes tested. The intrinsic rate of increase, finite rate of increase and weekly multiplication rate were higher at 30 °C, followed by 25 °C and 20 °C. The net reproductive rate of the female and gross reproduction rate were found to be the maximum at 25 °C followed by 30 °C and 20 °C. The results obtained from the field evaluations also showed a significant reduction in the O. coffeae population below ETL (Economic threshold level) level in the bio-control plot (T1) with reduction percentages of 86.85 and 76.42 in season-I and season-II, respectively, on the 7th day after the second release. By the end of the field study (on the 21st day), the bio-control plot (T1) had the highest reduction percentage of 77.95 and 78.48 compared to other treatments in both the seasons. The cost economics analysis done based on the field trials conducted indicated that, incorporation of bio-control methods would significantly reduce the costs of red spider mite control lower to the tune of 38.49% compared to standard estate practice. These findings can enhance Integrated Pest Management (IPM) programs for effective management of in the red spider mite in tea gardens.