# Polyandry in Noctuid Moths: Taxonomic, Bionomic, and Evolutionary Implications

## TL;DR

The paper explores how polyandry in Noctuid moths affects sexual selection and evolution, with implications for pest species and habitat generalists.

## Contribution

The study connects polyandry with genital asymmetry and speciation in Noctuid moths, suggesting evolutionary implications.

## Key findings

- Polyandry is common in pest and migrating Noctuid species, possibly enhancing heterozygosity.
- Secondary asymmetry in male genitalia correlates with increased species diversity in the subtribe Poliina.
- Habitat generalists like Orthosia and Conistra show varying levels of polyandry despite similar reproductive timing.

## Abstract

Polyandry, i.e., multiple copulations of one female with several different males, promotes sexual selection in moths. Copulation is a multi-phase process, since sperm are packed into spermatophores and then transferred to the female genitalia. When copulation occurs repeatedly within a few days, it can result in sexual selection and enhance heterozygosity. Pest and migrating species are often observed to be polyandrous. Polyandry occurs regularly in several genera of Noctuid moths. Some economically important Noctuids of temperate forests are also moderately (Orthosia) or highly (Conistra) polyandrous, in connection with their different life cycles and despite similar reproductive timing. Based on fecundity data, we hypothesised that habitat generalists should be more polyandrous than habitat specialists. However, our data are insufficient to determine whether ecology and/or phylogeny influence the level of polyandry. Other factors of practical importance, such as the relationship between the sex ratio and the level of polyandry, should be examined in the future.

Polyandry influences sexual behaviour and supports sexual selection in moths, incl. Noctuids. In polyandry, a female mates with multiple males within a few days. Copulation is a multi-phase process, as sperm are packed into spermatophores and transferred to the female genitalia. This process is costly, since spermatophore production and transfer is time-consuming. When this process is repeated, it results in sexual selection and enhances heterozygosity. Pest and migrating Noctuids are often polyandrous. Polyandry is common in the “pest clade” of Noctuidae (e.g., Euxoa, Dichagyris). We hypothesised that the asymmetric allocation of sensory and stimulating functions on the genitalia enhance sexual selection and promote speciation. In polyandrous species of the subtribe Poliina, we show that the evolution of the secondary asymmetry of male external genitalia is connected to an increase in species diversity. Some species inhabiting temperate forests were found to be moderately (Orthosia) or highly (Conistra) polyandrous, in connection with their different life cycles and despite similar reproductive timing. Based on fecundity data of some common species, we hypothesised that habitat generalists should be more polyandrous than habitat specialists. However, our data are insufficient to determine whether ecology and/or phylogeny influence the level of polyandry. Other factors, such as the connection between the sex ratio and the level of polyandry, should be surveyed in future studies, considering their relevance to plant protection.