Translator Disclaimer
6 December 2018 Sources of Variation in the Adult Flight of Walnut Husk Fly (Diptera: Tephritidae): A Phenology Model for California Walnut Orchards
Sara E. Emery, Nicholas J. Mills
Author Affiliations +
Abstract

A phenology model of the walnut husk fly, Rhagoletis completa Cresson, was developed to more accurately predict the timing of the flight period and optimize management decisions. A data set of 153 orchard years in which adults were trapped throughout the season was used for the development and validation of this model. Data from California Irrigation Management Information System (CIMIS) weather stations were used to match orchard-year datasets with historical climatic data on degree-day (DD) accumulation, winter chill, and winter rainfall. A cumulative Weibull distribution was used to model the relationship between cumulative trap catch and DD accumulation for R. completa in California. The model was used to predict thermal requirements for the start (5% cumulative trap catch) and mid-point (50% cumulative trap catch) of the flight period, which were 1,670 and 2,179 DDs, respectively. The prediction for 50% cumulative trap catch of R. completa in California was much higher than the thermal requirement estimated in Oregon previously (1,751 DDs). Linear mixed effects models were used to evaluate other environmental and orchard-specific factors which could explain the large variation between predicted and observed thermal requirements for both the start and mid-point of the flight period. Latitude, walnut cultivar leaf-out time, orchard age and year, as a continuous variable, all contributed significantly to explain deviations from the predictions of the DD model for individual orchard years. Such factors can be used both to adjust predicted thermal requirements for these two specific and informative stages of the flight period, and to provide a basis for ecological and evolutionary hypotheses.

© The Author(s) 2018. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Sara E. Emery and Nicholas J. Mills "Sources of Variation in the Adult Flight of Walnut Husk Fly (Diptera: Tephritidae): A Phenology Model for California Walnut Orchards," Environmental Entomology 48(1), 234-244, (6 December 2018). https://doi.org/10.1093/ee/nvy170
Received: 23 July 2018; Accepted: 1 November 2018; Published: 6 December 2018
JOURNAL ARTICLE
11 PAGES

This article is only available to subscribers.
It is not available for individual sale.
+ SAVE TO MY LIBRARY

Share
SHARE
KEYWORDS
degree day
latitude
orchard age
Rhagoletis completa
winter chill
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top