Effects of temperature on the developmental biology of Thaumatotibia batrachopa
Description
The macadamia nut borer, Thaumatotibia batrachopa, is one of the major pests of macadamia in South Africa. However, there is a lack of information on the effects of temperature on the developmental biology of this pest. We compared the effects of different constant temperatures on the pre-oviposition period, fecundity, mated adults' longevity, and development duration of the life stages. In addition, we determined the models that best illustrate temperature-dependent development rate and estimated thermal requirements. There was a significant variation between temperatures in all tested parameters. The pre-oviposition period, longevity, and development duration significantly increased with decreased temperature. The fecundity was highest at lower temperatures and lowest at higher temperatures. The T. batrachopa required 564.72 degree days to develop from egg to adult, with a Tmin of 10 degrees Celsius, Topt of 30 degrees Celsius, and Tmax of 36 degrees Celsius. Our findings align with the general trend of development duration, which increases with decreased temperatures. The degree days from our study will provide an accurate prediction of T. batrachopa phenology based on field temperatures and have various implications for managing this pest.
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Steps to reproduce
Collection of infested macadamia nuts The infested macadamia nuts were collected from commercial macadamia orchards, namely Barotta, Matrali, Shifuma, and Vhavenda in the Levubu area, Vhembe district, in the Limpopo province, South Africa . The collected infested macadamia nuts were placed in stack crates (53 ´ 35.5 ´ 29 cm) and maintained inside large breeding cages (90 ´ 60 ´ 60 cm) at 25 ± 1°C, 65 ± 10 %RH, and 14D:10L. The cages were monitored daily, and the late-instar larvae that emerged from the nuts to pupate were collected using tissue forceps and transferred to white, non-transparent plastic containers (14 × 14 × 7 cm) lined with dry paper towels and cotton wool, maintained at the same conditions. The pupae were removed within 24 h of formation, placed individually in 10ml plastic vials covered with cotton wool, and monitored daily until adult emergence. Temperature and relative humidity were recorded hourly using Thermochron ibuttons loggers (Semiconductor Corporation, Dallas/Maxin TX and USA), placed inside the insectary room for data logging. The Larvae, pupae, and adults were identified based on the morphological characteristics of T. batrachopa described by Rentel (2013). Pre-oviposition period and fecundity The newly emerged adults were paired (10 males and 10 females) and maintained at constant temperatures of 16°C, 21°C, 25°C, and 31°C under a 14L:10D photoperiod (Appendix C). The replicates were four at 16°C (N = 80), 17 at 21°C (N = 340), 11 at 25°C (N = 220), and six at 31°C (N = 120). The adults were provided with fresh, uninfested nuts (five per cage) as oviposition substrates. The cages were monitored daily for egg deposition. The nuts with eggs were removed within 24 h and replaced with fresh nuts. The preoviposition period was defined as the number of days from pairing to first oviposition. Fecundity was calculated as the total number of eggs deposited per cage divided by the number of females. Temperature-dependent development of T. batrachopa Freshly deposited eggs (within 24 h) from each temperature treatment were removed from the oviposition substrate and transferred with the nuts to plastic containers (14 × 14 × 7 cm), and maintained at their constant temperature. A total of 771, 2648,882, and 579 eggs were monitored at 16°C, 21°C, 25°C, and 31°C, respectively. The eggs were monitored daily to record hatching, and the newly hatched larvae were transferred using a fine paint brush into a prepared artificial False codling moth (FCM) diet (Moore et al., 2014), and modified by Smith (2020). The larvae were reared in 350 ml Consol jars (10 to 30 larvae), covered with cotton wool to maintain moisture and prevent escape. The larvae were monitored daily until late instar, after which they were transferred to containers for pupation.
Institutions
- University of VendaLimpopo, Thohoyandou
Categories
Funders
- NRF SARCHiGrant ID: 87311