Abstract: 【Aim】 The solitary wasp, Anterhynchium flavomarginatum is one of the most important natural enemies for the control of agricultural and forestry pests. This study aims to investigate the oviposition strategy and behavioral responses of A. flavomarginatum to parasitism pressure, so as to provide a basis for the biological control of agricultural and forestry pests. 【Methods】 During the three years (2018-2020), the oviposition strategy of A. flavomarginatum and its relationships with parasite pressures were investigated by using artificial trap-nests set according to kilometer-grid protocol (N=100 1-km² grids) in the Chebaling National Nature Reserve and its surrounding areas, Guangdong Province. The number of brood cells, sex ratio and parasitism in each trap-nest were recorded, and the length, innerdiameter, and architecture of each trap-nest were measured as well. 【Results】 During 2018-2020, we obtained 3 733 trap-nests and 9 269 brood cells with up to 1 420 brood cells parasitized. A. flavomarginatum laid an average of 2.50±1.25 eggs and constructed 1.84±1.14 non-brood cells per trap-nest with a male-biased sex ratio (male∶female=1.98∶1). For each nest-trap, offspring females tend to be laid in inner brood cells, while offspring males tend to be laid in outer brood cells. Structural equation model showed that both the inner diameter and the length of trap-nest positively affected the number of brood cells per trap-nest. The length of trap-nest also significantly positively affected the number of non-brood cells per trap-nest. However, both the number of brood cells and non-brood cells had a significantly negative influence on the parasitism rate. Meta-analysis of the sex arrangement pattern of offspring showed that number of offspring females in the innermost part of trap-nest was significantly higher than that in the outermost part, while the parasitism rate in the innermost part of trap-nest was significantly lower than that in the outermost part. 【Conclusion】 Our results provide sound evidence that oviposition strategy by A. flavomarginatum can help to improve its reproductive fitness, since this species tends to lay more eggs in trap-nests to reduce the parasitism risk and to improve the survival of offspring females by adjusting the sex allocation pattern of offspring within each trap-nest.

Key words: Solitary wasp; Anterhynchium flavomarginatum, trap-nests, oviposition strategy; nesting architecture, parasite pressure