TY - JOUR
T1 - A degree-day model for predicting adult emergence of the citrus gall wasp, Bruchophagus fellis (Hymenoptera Eurytomidae), in southern Australia
AU - Mo, Jianhua
AU - Stevens, Mark M.
N1 - Funding Information:
The study was part of a research project funded by Hort Innovation Australia with a levy from the Australian Citrus Industry. Andrew Creek and Steven Falivene helped with the selection of monitoring sites. Scott Munro, Peter Simmons, and Stephen Hegedus helped with data collection. Bernie Dominiak is thanked for providing constructive comments on an early version of the manuscript.
Publisher Copyright:
© 2021 Elsevier Ltd
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2021/1/23
Y1 - 2021/1/23
N2 - The citrus gall wasp, Bruchophagus fellis, is a serious pest of citrus in southeast Australia and the ability to accurately predict its highly synchronised adult emergence periods is critical for its effective management. We monitored emergence of the citrus gall wasp for six years during 2010–2017 in southern Australia, yielding a total of 22 site-by-year datasets from two citrus production regions and multiple citrus varieties. For each dataset, the proportions of emerged wasps on different monitoring dates were related to the corresponding degree-days using a 2-parameter Weibull function. The two degree-day parameters, the lower development threshold temperature and biofix date, were estimated at 8 °C and August 1 respectively by cross-validation of a series of candidate values using the sum of squared differences between the predicted and observed median emergence dates as the performance indicator. According to the final fitted Weibull function, 5, 50, and 95% emergence occur when 560, 723 and 835 degree-days above 8 °C have accumulated after August 1. The predicted median emergence dates differed from the corresponding observed median emergence dates by an average of 2.8 days across the 22 datasets. The average deviations for 5 and 95% emergence were slightly larger, at five and four days, respectively. Observed degree-days for median emergence did not differ significantly between the two citrus production regions, indicating there is no need for separate degree-day models for different regions. Based on the degree-day model, an interactive, online timing tool has been developed, allowing growers to use local weather station data to predict when the gall wasp is likely to emerge in average, warm, and cool years.
AB - The citrus gall wasp, Bruchophagus fellis, is a serious pest of citrus in southeast Australia and the ability to accurately predict its highly synchronised adult emergence periods is critical for its effective management. We monitored emergence of the citrus gall wasp for six years during 2010–2017 in southern Australia, yielding a total of 22 site-by-year datasets from two citrus production regions and multiple citrus varieties. For each dataset, the proportions of emerged wasps on different monitoring dates were related to the corresponding degree-days using a 2-parameter Weibull function. The two degree-day parameters, the lower development threshold temperature and biofix date, were estimated at 8 °C and August 1 respectively by cross-validation of a series of candidate values using the sum of squared differences between the predicted and observed median emergence dates as the performance indicator. According to the final fitted Weibull function, 5, 50, and 95% emergence occur when 560, 723 and 835 degree-days above 8 °C have accumulated after August 1. The predicted median emergence dates differed from the corresponding observed median emergence dates by an average of 2.8 days across the 22 datasets. The average deviations for 5 and 95% emergence were slightly larger, at five and four days, respectively. Observed degree-days for median emergence did not differ significantly between the two citrus production regions, indicating there is no need for separate degree-day models for different regions. Based on the degree-day model, an interactive, online timing tool has been developed, allowing growers to use local weather station data to predict when the gall wasp is likely to emerge in average, warm, and cool years.
KW - Adult emergence
KW - Bruchophagus fellis
KW - Citrus gall wasp
KW - Degree-day model
KW - Online timing tool
KW - Phenology
UR - http://www.scopus.com/inward/record.url?scp=85100068099&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85100068099&partnerID=8YFLogxK
U2 - 10.1016/j.cropro.2021.105553
DO - 10.1016/j.cropro.2021.105553
M3 - Article
AN - SCOPUS:85100068099
VL - 143
SP - 1
EP - 7
JO - Crop Protection
JF - Crop Protection
SN - 0261-2194
M1 - 105553
ER -