Past thermal conditions affect hunting behaviour in larval antlions

Abstract

Some sit-and-wait predators, such as antlion larvae, construct traps to capture passing prey. The location of these traps depends on many abiotic and biotic factors, including temperature and the presence of conspecifics, which probably stimulate behaviours that minimize the costs and maximize the benefits of trap building. Here, we exposed second instar antlion larvae to elevated temperatures of 25°C (mild treatment) or 31°C (harsh treatment) for one month and then transferred them to common conditions (20°C) to examine the effects of previous thermal treatment on aggregation tendency and trap size. We predicted that antlions that experienced harsh conditions would subsequently increase the neighbouring distance and trap diameter to reduce competition with conspecifics and improve prey capture success, compensating for past conditions. In contrast with these predictions, antlions exposed to harsh conditions displayed a trend in the opposite direction, towards the decreased neighbouring distance. Furthermore, some of these antlions also built smaller traps. We discuss possible reasons for our results. The effects of previous thermal exposure have rarely been considered in terms of trap construction in antlions. Described effects may possibly apply to other sit-and-wait predators and are significant considering that many of these predators are long-lived.

Operant conditioning in antlion larvae and its impairment following exposure to elevated temperatures

“…Here, we show that heat might result in memory impairment. This finding expands our current knowledge about the multifaceted effects of heat on antlion larvae (Alcalay et al 2014 ; Miler et al 2020 ; Miler and Czarnoleski 2021 ). Antlions are capable of behavioural thermoregulation (Green 1955 ; Marsh 1987 ; van Zyl et al 1996 ; Abraham 2003 ) and similar to other taxa may likely adjust to heat by changing their microhabitat utilization, activity time, or hunting strategy (Ma et al 2018 ; Johnson et al 2020 ; Gotcha et al 2021 ).…”

Heat stress during development makes antlion larvae more responsive to vibrational cues

“…We performed 2 thermal performance tests on a subset of larvae ( N = 24 in each test) following established methods and our previous research on another antlion species ( Miler and Czarnoleski 2021 ). The first test recorded the temperatures chosen freely by larvae exposed to a thermal gradient.…”

Shadow competition: its definition, prevalence, causes and measurement

“…4). A higher capture probability for downstream predators can be explained, for example, by the prey's lower speed or weakening/injury after unsuccessful attacks by predators upstream (Baker and Zemel 2000, Pruitt et al 2009, Rao 2009, Miler and Czarnoleski 2021). However, the prey may also become more vigilant following the first predator attack and consequently be even harder to catch (Lima et al 2003, Beauchamp 2020).…”