Is flying riskier for female katydids than for males?

Saha, K and Prakash, H and Mohapatra, PP and Balakrishnan, R (2023) Is flying riskier for female katydids than for males? In: Behavioral Ecology and Sociobiology, 77 (2).

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Abstract

Abstract: Morphological and behavioural differences between the sexes often make one sex of a species more vulnerable to predation than the other. Onomarchus uninotatus, a canopy katydid, forms an important component of the diet of the insectivorous bat Megaderma spasma. Examination of culled prey remains in M. spasma roosts suggested that female O. uninotatus may be at higher risk of predation than males. As in many insects, the females of O. uninotatus are larger and heavier and might be easier for predators to detect and capture and/or preferred for their higher nutritive value. We tested these hypotheses by conducting behavioural experiments in an outdoor enclosure, examining the bat predator approach to free-flying O. uninotatus and their capture success. We found that the flying female and male katydids were equally likely to be approached, but males were captured more by M. spasma, with a weak effect. This indicates that females may have a better escape strategy after being approached. We then asked whether females were at higher risk of predation because they moved more often or for longer durations across trees than males, in search of mates and egg-laying sites. We investigated landscape-level movement patterns of O. uninotatus females and males using VHF radio-telemetry. Females had 1.6 times higher frequency of movement and 1.8 times greater displacement across trees than males. This difference may be ecologically important and cause higher bat predation risk on females. Significance statement: Studying the factors affecting sex-specific levels of predation risk is crucial to better understand the natural selection and the hypothesised causes and consequences of sexual dimorphism. Katydid females, including Onomarchus uninotatus, are at a higher risk of bat predation than males, and flying is one of the most risky prey behaviours. Onomarchus uninotatus females are larger than males, which could make them easier to detect and capture. Our experiments involving free-flying bats and katydids showed, however, that bat approaches are similar for flying females and males. Females might be better at escaping bat captures after being approached. Katydid males typically broadcast acoustic signals, and females move towards these signals, potentially placing females at higher predation risk. Radio-telemetry studies revealed that on average, females were likely to move more often with greater displacements across trees, which may place them at higher risk of predation. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Item Type:	Journal Article
Publication:	Behavioral Ecology and Sociobiology
Publisher:	Springer Science and Business Media Deutschland GmbH
Additional Information:	The copyright for this article belongs to Springer Science and Business Media Deutschland GmbH.
Keywords:	bat; biotelemetry; natural selection; predation risk; predator; sexual dimorphism
Department/Centre:	Division of Biological Sciences > Centre for Ecological Sciences
Date Deposited:	15 Mar 2023 05:46
Last Modified:	15 Mar 2023 05:46
URI:	https://eprints.iisc.ac.in/id/eprint/80983

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