Climate and seasonal effects on phenology and biological control of giant whitefly Aleurodicus dugesii (Hemiptera: Aleyr
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Climate and seasonal effects on phenology and biological control of giant whitefly Aleurodicus dugesii (Hemiptera: Aleyrodidae) with parasitoids in southern California, USA Erich N. Schoeller
. Richard A. Redak
Received: 28 February 2020 / Accepted: 11 June 2020 International Organization for Biological Control (IOBC) 2020
Abstract The invasive giant whitefly Aleurodicus dugesii Cockerell (Hemiptera: Aleyrodidae), a pest of many important crops and ornamentals, has established throughout southern California, USA. The parasitoids Encarsia noyesi Hayat (Hymenoptera: Aphelinidae), Idioporous affinis LaSalle and Polaszek (Hymenoptera: Pteromalidae), and Entedononecremnus krauteri Zolnerowich and Rose (Hymenoptera: Eulophidae) were introduced as part of a classical biological control program against giant whitefly. Populations of giant whitefly can still reach high numbers, however, despite biological control efforts. Seasonal variation in giant whitefly population densities and parasitoids’ species-specific parasitism rates across three climates types in southern California were examined by repeated censuses during 2015–2016 in order to identify potential underlying factors influencing giant whitefly population dynamics. Giant whitefly population densities did not vary between southern California climate types, but varied seasonally, with the highest observed population densities in the spring. Parasitism rates of all three parasitoids also varied seasonally, with total parasitism reaching a peak in late summer and declining until the start of spring.
Handling Editor: Dirk Babendreier E. N. Schoeller (&) R. A. Redak Department of Entomology, University of California, 900 University Avenue, Riverside, CA 92521, USA e-mail: [email protected]
Only I. affinis parasitism rates varied between climate types. Parasitism rates of I. affinis were the highest of the three parasitoid species observed, followed by E. noyesi and E. krauteri. Potential explanations for these findings and their impact on giant whitefly control are discussed. Keywords Parasitoids Whitefly Phenology Biological control
Introduction The impact of climate on the dynamics of hostparasitoid interactions and interactions between multiple parasitoid species is of interest due to the frequent use of parasitoids as biological control agents (Naranjo et al. 2015; Cock et al. 2016). Climate and variations in weather are important regulators of the distribution and abundance of insects (Price 1987; Bourchier and Smith 1996; Crozier 2004), and climate specifically (Stiling 1990; Sorribas et al. 2010) has been shown to impact the success of parasitoids. Sensitivity to changes in climatic conditions is predicted to be highest at the upper trophic levels (Voigt et al. 2003), with parasitoids being particularly sensitive (Hance et al. 2007; Wetherington et al. 2017). Tightly coupled population dynamics with their host is critical for the success of parasitoids (Hance
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