Impact of Trichogramma parasitoid age on the outcome of multiparasitism in the factitious host eggs of Chinese oak silkworm, Antheraea pernyi

Asim Iqbal,Lucie S Monticelli,Lian-Sheng Zang,Yong-Ming Chen,Yang-Yang Hou,Asad Ali,Nicolas Desneux

doi:10.1007/s10340-020-01239-1

Abstract

The age of Trichogramma parasitoids could influence biological traits which are of great importance for effectiveness of mass rearing systems. Recent studies demonstrated that Trichogramma ostriniae (TO) could parasitize Antheraea pernyi eggs through multiparasitism along with other Trichogramma species, although few adults could emerge successfully. It is important to characterize the factors modulating the performance of TO on A. pernyi eggs, notably in order to try enhancing its quantitative emergence through multiparasitism for further use in biological control. In this context, irrespective of host age, we tested different ages of TO females (from 0.5-day- to 6-day-old postemergence) in multiparasitism with Trichogramma chilonis (TC) on A. pernyi eggs. The results of the present study confirmed that TO parasitism on A. pernyi eggs was largely age dependent. Higher percentage of multiparasitism and higher number of emerged TO adults were recorded in the treatment where 3-day-old TO females were used for parasitization with TC on A. pernyi host. In addition, we also tested different female ratios of both Trichogramma species to find out an optimal ratio for use in mass production. The highest percentage of multiparasitism, emergence and optimum emerged number of TO (per A. pernyi egg) was observed with the ratio 3:2 (TO:TC) per 1 host egg. This study demonstrated that the age of TO females can significantly affect their performance in multiparasitism of large A. pernyi eggs. These results prompt for more research in order to develop an effective multiparasitism-based production of TO at the industrial scale.

Highlights

Introduction1996; Tabone et al 2010; Yuan et al 2012; Chailleux et al 2013; Du et al 2017; Guo et al 2019; Zang et al 2021)
The treatments where 0.5-day, 1-dayand 2-day-old the ratios 15:10 (TO) females were used for parasitizing A. pernyi eggs with Trichogramma chilonis (TC) showed significantly lower percentages of multiparasitism (20%, 22% and 28%, respectively) than when 3-day- and 4-day-old females were used (76% and 72%, respectively)
The percentages of multiparasitism were decreased to 40% and 12% in the treatments where 5-day- and 6-day-old TO females were used for parasitization, respectively

Summary

Introduction

1996; Tabone et al 2010; Yuan et al 2012; Chailleux et al 2013; Du et al 2017; Guo et al 2019; Zang et al 2021) These parasitoids are key biological control agents against various agricultural pests in China (Zang et al 2021). Ostrinia furnacalis is a key economic pest of corn in China, causing an average of 6–9 million tons yield losses per year (Wang et al 2014). Inundative releases of T. ostriniae against O. furnacalis in corn are on average 75,000–120,000 per hectare, and result in over 90% parasitism and successful control of the pest (Wang et al 2000)

Methods

Results

Conclusion