Interpopulation variation in kairomone use by Cyrba algerina, an araneophagic jumping spider from Portugal

Abstract

Geographic variation in a predator's reliance on kairomones from prey was investigated. The predator studied, Cyrba algerina, is an araneophagic (spider-eating) jumping spider (Salticidae) and the prey were oecobiid spiders (Oecobiidae). There were two study sites (Sintra and Tavira), both in Portugal. Oecobius machadoi was a common oecobiid in Sintra, but no oecobiids were found in Tavira. Staged encounters showed that oecobiid-specific prey-capture behaviour was adopted by the C. algerina in Sintra but not in Tavira. In experiments using a Y-shaped olfactometer, significantly more Sintra C. algerina individuals chose the side with oecobiid odour instead of the blank side when the odour came from females of a sympatric species (O. machadoi), but not when the odour came from O. machadoi males or from females of an allopatric species (O. amboseli). Regardless of whether the odour came from O. machadoi or O. amboseli, the Tavira C. algerina did not choose the odour side significantly more often than the blank side. These findings suggest that, in Sintra, C. algerina is locally adapted to a locally abundant oecobiid species. Whether this example of geographic variation in kairomone use is a behavioural ecotype or instead an instance of phenotypic plasticity is currently unknown.

Widespread reliance on olfactory sex and species identification by lyssomanine and spartaeine jumping spiders

“…It is known that the females of species from two salticoid genera, Evarcha (Jackson et al ., ) and Naphys (Clark, Jackson & Cutler, ), and two spartaeine genera, Cyrba and Portia (Clark, Harland & Jackson, ; Jackson, Clark & Harland, ; Cerveira & Jackson, ), can identify the odour of particular types of prey. Other contexts in which lyssomanine and spartaeine females, as well as males, might make use of olfactory cues should also be considered.…”

“…For each species, all individuals used (Table ) were from laboratory cultures (2nd and 3rd generation) and, after dispersal from the egg sac, none of these individuals had encounters with other salticids. For rearing and maintenance, we adopted the standard procedures routinely used in our laboratory for salticid research (see Jackson & Hallas, ; Cerveira & Jackson, ), with all tests beginning between 0800 and 1500 h (laboratory photoperiod 12L:12D, lights on at 0700 h) and no individual spider being used more than once as a test spider or source spider, a source spider being an individual which provided the potential pheromones to which the test spider was exposed. All test and source spiders were unmated adults that had matured 2–3 weeks before testing and had fasted for 4–5 days before use.…”

Mosquito-terminator spiders and the meaning of predatory specialization

“…However, mosquitoes are not particularly dangerous and yet the level of specificity shown by E. culicivora is exceptional (Table 1). Moreover, E. culicivora is one of the few salticids Cerveira & Jackson 2011) known to be proficient at identifying preferred prey even when restricted to using olfaction alone .…”

Attending to detail by communal spider-eating spiders

“…Like P. africana juveniles, C. algerina settles beside nests occupied by oecobiids, intermittently probing or striking the nest and capturing the oecobiid either as it leaves the nest or later when it returns to the nest (Cerveira and Jackson 2011;Guseinov et al 2004). However, P. africana juveniles differ from C. algerina by practising communal predation, suggesting that communal predation may favour ability to base foraging decisions on particularly fine detail.…”