Animal communication theory predicts that low-frequency cheating should be common in generally honest signalling systems. However, perhaps because cheats are designed to go undetected, there are few examples of dishonest signals in natural populations. Here we present what we believe is the first example of a dishonest signal which is used commonly by males to attract mates and fight sexual rivals. After losing their large claw male fiddler crabs (Uca annulipes) grow a new one which has less mass, is a less effective weapon and costs less to use in signalling than an equivalent-length claw of the original form. Males with original claws do not differentially fight males with regenerated claws even though they are likely to win. Regenerated claws effectively bluff fighting ability and deter potential opponents before they fight. During mate searching, females do not discriminate against males with low-mass, regenerated claws, indicating that they are deceived as to the true costs males pay to produce sexual signals. Up to 44% of males in natural populations have regenerated claws, a level unanticipated by current signalling theory. The apparent rarity of cheating may be an artefact of the usual difficulty of detecting cheats and dishonesty may be quite common.

Abstract. Variation among populations in extrinsic mortality schedules selects for different patterns of investment in key life-history traits. We compared life-history phenotypes among 12 populations of the live-bearing fish Brachyrhaphis episcopi. Five populations co-occurred with predatory fish large enough to prey upon adults, while the other seven populations lacked these predators. At sites with large predatory fish, both sexes reached maturity at a smaller size. Females of small to average length that co-occurred with predators had higher fecundity and greater reproductive allotment than those from populations that lacked predators, but the fecundity and reproductive allotment of females one standard deviation larger than mean body length did not differ among sites. In populations with large predatory fish, offspring mass was significantly reduced. In each population, fecundity, offspring size and reproductive allotment increased with female body size. When controlling for maternal size, offspring mass and number were significantly negatively correlated, indicating a phenotypic trade-off. This tradeoff was non-linear, however, because reproductive allotment still increased with brood size after controlling for maternal size. Similar differences in life-history phenotypes among populations with and without large aquatic predators have been reported for Brachyrhaphis rhabdophora in Costa Rica and Poecilia reticulata (a guppy) in Trinidad. This may represent a convergent adaptation in life-history strategies attributable to predator-mediated effects or environmental correlates of predator presence.

Background: Pediculiasis is treated aggressively in the United States, mainly with permethrin-and pyrethrincontaining pediculicides. Increasingly frequent anecdotal reports of treatment failure suggest the emergence of insecticidal resistance by these lice. Objective: To confirm or refute the susceptibility of head lice sampled in the United States to permethrin. Design: Survey. Head lice were removed from children residing where pediculicides are readily available and where such products are essentially unknown. Their survival was compared following exposure to residues of graded doses of permethrin in an in vitro bioassay. Setting: School children from Massachusetts, Idaho, and Sabah (Malaysian Borneo). Subjects: In the United States, 75 children aged 5 to 8 years. In Sabah, 59 boys aged 6 to 13 years. Virtually all sampled US children had previously been treated with pediculicides containing pyrethrins or permethrin; none of the Sabahan children were so exposed. Main Outcome Measure: Survival of head lice exposed to permethrin. Results: Permethrin did not affect head lice sampled from chronically infested US children who had previously been treated for pediculiasis. The slope of the dose-response regression line for these lice did not differ significantly from zero (P = .66). This pediculicide immobilized lice sampled in Sabah. Mortality correlated closely with permethrin concentration (P = .008). Conclusions: Head lice in the United States are less susceptible to permethrin than are those in Sabah. The pyrethroid susceptibility of the general population of head lice in the United States, however, remains poorly defined. Accordingly, these relatively safe over-thecounter preparations may remain the pediculicides of choice for newly recognized louse infestations.

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The role of lone star ticks as vectors for Rocky Mountain spotted fever (RMSF) remains poorly described. We compared the entomological inoculation rates (EIRs) for Rickettsia spp. for representative sites in Missouri and Kansas, states that frequently report RMSF each year. Host-seeking ticks were collected during 2006 and pooled tick homogenates analyzed by polymerase chain reaction to detect probable R. rickettsii, with confirmation for multiple gene targets performed on individual ticks from pools that screened positive. Of 870 adult and nymphal lone star ticks, Amblyomma americanum (L.), 0.46% contained DNA of Rickettsia rickettsii. Interestingly, two of these positive ticks were concurrently infected by R. amblyommii. More than 90% of lone star tick pools contained R. amblyommii DNA. Of 169 dog ticks that were analyzed, none were infected by R. rickettsii. The entomological inoculation rate for spotted fever group (SFG) rickettsiae within lone star ticks was an order of magnitude greater than that for dog ticks. We conclude that lone star ticks may be epidemiologically significant vectors of Rocky Mountain spotted fever and of spotted fever group rickettsiae.

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Field and laboratory observations of mating behaviour in a population of the tropical millipede Alloporus uncinatus were carried out over one breeding season. Males obtained mates through random encounters and by forming triplet associations with copula pairs. The occurrence of triplet associations in the field was coincident with a highly male biased operational sex ratio. Mate acquisition by males was apparently stochastic and direct physical competition did not occur. In laboratory experiments mating was size-selective probably as a consequence of female choice. We consider the possibility that sperm competition has contributed to the evolution of the mating system in this species.