Reproductive benefits derived from defensive plant alkaloid possession in an arctiid moth (
            <i>Utetheisa ornatrix</i>
            )

Many herbivorous insects sequester defensive chemicals from their host plants. We tested sequestration fitness costs in the specialist moth Utetheisa ornatrix (Lepidoptera: Arctiidae). We added pyrrolizidine alkaloids (PAs) to an artificial diet at different concentrations. Of all the larval and adult fitness components measured, only development time was negatively affected by PA concentration. These results were repeated under stressful laboratory conditions. On the other hand, the amount of PAs sequestered greatly increased with the diet PA concentration. Absence of a detectable negative effect does not necessarily imply a lack of costs if all individuals express the biochemical machinery of detoxification and sequestration constitutively. Therefore, we used qPCR to show that expression of the gene used to detoxify PAs, pyrrolizidine-alkaloid-N-oxygenase (pno), increased 41-fold in our highest PA treatment. Nevertheless, fitness components were affected only slightly or not at all, suggesting that sequestration in this species does not incur a strong cost. The apparent lack of costs has important implications for our understanding of the evolution of ecological interactions; for example, it implies that selection by specialist herbivores may decrease the levels of certain chemical defences in plant populations.

show abstract

“…; Del Campo et al . ; Hartmann et al . ) and some other insects (Rowell‐Rahier & Pasteels ; Bowers ; Fordyce ; Kearsley & Whitham ).…”

Section: Discussionmentioning

confidence: 99%

A free lunch? No cost for acquiring defensive plant pyrrolizidine alkaloids in a specialist arctiid moth (Utetheisa ornatrix)

2012

View full text Add to dashboard Cite

show abstract

“…If a large ejaculate has a combined effect of elevating rates of oviposition and reducing female lifespan, the lifetime fecundity of females receiving large doses of ‘harmful’ seminal products may, in reality, be no different from that of females receiving smaller doses; the reproductive output of the female will just have been condensed into a shorter time‐span (see Chapman et al. 2003a; Del Campo et al. 2005).…”

Section: Does Nuptial Feeding Lead To Sexual Conflict or Sexual Concumentioning

confidence: 99%

All that Glisters is not Gold: Sensory Bias, Sexual Conflict and Nuptial Feeding in Insects and Spiders

2007

View full text Add to dashboard Cite

It is becoming increasingly clear that the evolutionary interests of the sexes are often in conflict when it comes to mating. Sexual encounters involving nuptial gifts, however, have often been viewed as prime examples of sexual co-operation, rather than conflict. In this review, I explore the proposition that nuptial gifts act as sensory traps: by exploiting the female's gustatory responses, the male may be able to entice females to accept superfluous matings and/or transfer greater volumes of ejaculate than are in the female's reproductive interests. Evidence suggests that the females' sensory biases may have played an important role in shaping gift characteristics in at least four different systems, although relatively few forms of nuptial feeding have so far been examined from this perspective. I argue that gift composition is more likely to be tailored to increasing the attractiveness of the gift to the female and/or maximizing gift handling time than to suit the female's nutritional needs and that the fecundity-enhancing benefits of nuptial gifts are often questionable and have been over-stated in the literature. Fertilization biases associated with the female's attraction to the nuptial gift, however, could lead to in-direct benefits for the female. On the other hand, nuptial feeding may also lead to significant costs to the female. Evidence suggests that some types of gift entice the female to mate, but it is not clear whether the resultant degree of polyandry is higher than optimal for the female. In other cases, evidence suggests that the gift enables the male to overcome the resistance of the female to accepting an extra large ejaculate and that large ejaculates are associated with longer post-mating sexual refractory periods in the female. This could represent a cost to the female by delaying or preventing her from receiving the genetic benefits of polyandry. At present, it is not clear, however, whether such costs outweigh the potential benefits of nuptial feeding for the female

show abstract

“…The defences invested in by insect larvae often build up over time and can sometimes be retained into the adult form (Müller et al 2001;Pasteels et al 2003;Hartmann et al 2004;del Campo et al 2005). The amount of chemical defences available after pupation influences reproductive success in many insects because chemical defences reduce predation (Brower 1984;Nishida and Fukami 1990), increase mating success (Nishida and Fukami 1990;Amano et al 1999;Labeyrie et al 2003), and/or increase survival of offspring where eggs are chemically defended (Whitman et al 1990).…”

Section: Introductionmentioning

confidence: 96%

Dynamic state-dependent modelling predicts optimal usage patterns of responsive defences

Higginson

Ruxton

2009

Oecologia

View full text Add to dashboard Cite

Chemical defences against predation often involve responses to specific predation events where the prey expels fluids, such as haemolymph or gut contents, which are aversive to the predator. The common link is that each predation attempt that is averted results in an energetic cost and a reduction in the chemical defences of the prey, which might leave the prey vulnerable if the next predation attempt occurs soon afterwards. Since prey appear to be able to control the magnitude of their responses, we should expect them to trade-off the need to repel the current threat against the need to preserve defences against future threats and conserve energy for other essential activities. Here we use dynamic state-dependent models to predict optimal strategies of defence deployment in the juvenile stage of an animal that has to survive to maturation. We explore the importance of resource level, predator density, and the costs of making defences on the magnitude of the responses and optimal age and size at maturation. We predict the patterns of investment and the magnitude of the deployment of defences to potentially multiple attacks over the juvenile period, and show that responses should be smaller when the costs of defences and/or predation risk are higher. The model enables us to predict that animals in which defences benefit the adult stage will employ different strategies than those that do not use the same defences as adults, and thereby experience a smaller reduction in body size as a result of repeated attacks. We also explore the effect of the importance of adult size, and find that the sex and mating system of the prey should also affect defensive strategies. Our work provides the first predictive theory of the adaptive use of responsive defences across taxa.

show abstract

Reproductive benefits derived from defensive plant alkaloid possession in an arctiid moth ( Utetheisa ornatrix )

Cited by 20 publications

References 23 publications

A free lunch? No cost for acquiring defensive plant pyrrolizidine alkaloids in a specialist arctiid moth (Utetheisa ornatrix)

A free lunch? No cost for acquiring defensive plant pyrrolizidine alkaloids in a specialist arctiid moth (Utetheisa ornatrix)

All that Glisters is not Gold: Sensory Bias, Sexual Conflict and Nuptial Feeding in Insects and Spiders

Dynamic state-dependent modelling predicts optimal usage patterns of responsive defences

Contact Info

Product

Resources

About