Factors Affecting the Reproduction and Mass-Rearing of Sclerodermus brevicornis (Hymenoptera: Bethylidae), a Natural Enemy of Exotic Flat-Faced Longhorn Beetles (Coleoptera: Cerambycidae: Lamiinae)

Abstract

Many species of long-horned beetles are invasive pests causing significant economic damage in agro-forestry systems. They spend the majority of their life-cycle concealed inside natural wood or wooden packaging materials and are largely protected from adverse environmental conditions and pesticide sprays. Biological control via parasitoid natural enemies including members of the bethylid genus Sclerodermus, has proven effective against some long-horned beetles that are invasive in China. In Europe, the biocontrol potential of native Sclerodermus species is being evaluated with a view to developing efficient mass-rearing techniques and then actively deploying them against invasive Asian beetles. Here, we continue evaluations of S. brevicornis by establishing that groups of females that have already reared offspring to emergence are capable of reproducing subsequent hosts and by evaluating the lifetime reproductive capacity of individual females provided with successive hosts. Additionally, we assess the laboratory shelf-life of adult females stored for different times at different temperatures including cold storage, and then assess the post-storage reproductive performance of groups of females provided with a single host. We found that adult female longevity declines with increasing storage temperature and that most aspects of subsequent performance are negatively affected by high temperatures. The adaptability to low temperature storage enhances the suitability of S. brevicornis to mass-rearing programs and thus biocontrol deployment.

How many cooperators are too many? Foundress number, reproduction and sex ratio in a quasi‐social parasitoid

“…However, if one foundress could control the sex allocation of the other, we would expect that the ESS for the dominant foundress would be to produce only as many sons as could inseminate all female offspring maturing within the group and to allow the subordinate foundress to produce female offspring only. If sex allocation dominance were substantial, we would expect sex ratios to be very strongly female biased, irrespective of foundress number (as observed in this study and previously by Hong et al, 2008; Li et al, 2010; Li & Sun, 2011; Tang et al, 2014; Lupi et al, 2017; Wang et al, 2016; Wei et al, 2017; Yang et al, 2018; Abdi et al, 2020a; Jucker et al, 2020; Zhao et al, 2020). We would also expect that, due to limited mating capacity of adult males, the numbers of males in broods would increase gradually as brood sizes increase (as observed in this study and previously by Kapranas et al, 2016; Abdi et al, 2021).…”

“…Females were then stored in a refrigerator (5 ± 0.5°C) to synchronise parasitoid and host availability on emergence and were around two weeks old when used in experiments. Previous studies have shown that such storage does not greatly affect their subsequent performance (Jucker et al, 2020). Cultures were maintained in a climate chamber at 25 ± 1°C, a 16 L:8D diurnal cycle and a relative humidity of 60 ± 5%.…”

“…Previous studies have shown that such storage does not greatly affect their subsequent performance (Jucker et al, 2020). Cultures were maintained in a climate chamber at 25 AE 1 C, a 16 L:8D diurnal cycle and a relative humidity of 60 AE 5%.…”

Cooperative interactions among females can lead to even more extraordinary sex ratios

“…2020a,b,c; Jucker et al. 2020). These cases therefore suggest that we need to identify additional factors that can favor female‐biased sex ratios.…”

A case of frozen behaviour: A flat wasp female with a beetle larva in its grasp in 100-million-year-old amber

“…Evans 1962). Yet, studies of behaviour and also their biology at large are mostly restricted to species of agricultural importance, as their immatures parasitise some crop and storage pests (Kühne and Becker 1974;Gordh and Hawkins 1981;Gordh 1998;Cheng et al 2004;Gao et al 2016;Jucker et al 2020).…”