Pioneer-Follower dilemma game in Acanthoscelides obtectus (Coleoptera: Bruchidae)

Abstract

Larvae of Acanthoscelides obtectus show two contrasting behaviors when entering a bean. One is pioneer behavior in which a larva enters the bean through an entrance hole made by itself; the other is follower behavior in which a larva enters the bean through an entrance hole made by a pioneer. Previous studies have shown that the number of followers is much greater than that of pioneers. If there is a cost to being a pioneer, and if larvae can choose either of the two strategies, there is a dilemma: to be a pioneer or not. This dilemma is similar to the chicken game because if all larvae avoid choosing the risky pioneer strategy in favor of the follower strategy, none of the larvae can enter a bean, and they will die. In the present study, in order to investigate whether the larvae of A. obtectus are facing a dilemma of entry order, we experimentally measured the cost to pioneers and tested the flexibility of larval entering strategies. Pioneers' costs were measured by entrance success rate, and the flexibility of larval strategies was tested by gauging the proportion of pioneers at various larval densities. The entrance success of pioneers was lower than that of followers, and the proportion of pioneers decreased as the number of competing larvae increased. These results suggest that the Pioneer-Follower interaction in A. obtectus satisfies the conditions for a dilemma game: the larvae of A. obtectus are in a dilemma of entry order.

The evolution of host manipulation by parasites: a game theory analysis

“…Our models' predictions apply not only to trematodes but also to any organism whose investment can be exploited by others such as bean weevils burrowing into beans (Ohtsuka and Toquenaga 2008), foraging birds (Fernández-Juricic et al 2005) whose food is ''scrounged'' by others (Vickery et al 1992) and other parasitic worms capable of manipulating their intermediate hosts, such as cestodes and acanthocephalans (e.g., Rosen and Dick 1983;Dezfuli et al 2001;Parker et al 2003;Michaud et al 2006). In these other groups, the genetic relatedness within groups will differ from that observed in trematodes.…”

Host shift induces changes in mate choice of the seed predator Acanthoscelides obtectus via altered chemical signalling

“…First-instar larvae entering the seeds chew through the seed coat and then spit it out, a behaviour performed possibly to avoid toxic lignin, polyphenolic or condensed tannin compounds present in the testa [ 51 ]. Being mobile, they can actively choose between host plants [ 52 ] and thus may increase their chance of survival if given the choice between seeds. Apart from the genetically determined host range, there is no information exchange between the female and the L1 larvae about the suitability of substrates, resulting in the lack of positive correlation between female oviposition preference and larval performance.…”

A semiochemical view of the ecology of the seed beetle Acanthoscelides obtectus Say (Coleoptera: Chrysomelidae, Bruchinae)

“…Some of these compounds can reach high concentrations in legume seeds: tannins comprise 5% of the dry weight of Vicia faba seed testa (Boughdad et al, 1986), whereas phaseolin can reach as much as 16.7% dry weight in P. lunatus (Moraes et al, 2000). Seed coat toxins might partially be the reason why L1 larvae prefer to enter the seed via holes pre-drilled by conspecifics (Labeyrie, 1960;Ohtsuka & Toquenaga, 2009). Larval development to adulthood is ultimately determined by the chemical composition of the cotyledon and is affected by the presence of SPMs, although it is appreciated here that no clear distinction exists between so-called primary and secondary plant metabolites (Erb & Kliebenstein, 2020).…”

“…Some of these compounds can reach high concentrations in legume seeds: tannins comprise 5% of the dry weight of Vicia faba seed testa (Boughdad et al, 1986 ), whereas phaseolin can reach as much as 16.7% dry weight in P. lunatus (Moraes et al, 2000 ). Seed coat toxins might partially be the reason why L1 larvae prefer to enter the seed via holes pre‐drilled by conspecifics (Labeyrie, 1960 ; Ohtsuka & Toquenaga, 2009 ).…”