Robert B. Kimsey

Variation in Developmental Time for Geographically Distinct Populations of the Common Green Bottle Fly, Lucilia sericata (Meigen)

Abstract:  Time between death and discovery of remains, or postmortem interval (PMI), can be assessed using blow fly maggot age. Forensic entomologists rely on published, often nonlocal, species‐specific developmental tables to determine maggot age. In a series of common garden experiments, we investigated the developmental rate variation between populations of Lucilia sericata collected from Sacramento, CA, San Diego, CA, and Easton, MA at 16°C, 26°C, and 36°C. For the 16°C trial the time measurement started at egg hatch, while for the higher temperatures the experiment began at oviposition; the wandering stage signified the endpoint for all experiments. The distribution of developmental times differed significantly (ANOVA, p < 0.001) between the three populations within each temperature treatment. We discovered that regional variation of developmental times within a blow fly species exists. This study demonstrates the importance of assembling local population‐specific developmental tables when estimating larval age to determine PMI.

Ehrlichia spp. in cervids from California.

Blood samples from six mule deer (Odocoileus hemionus hemionus), 15 black-tailed deer (O. hemionus columbianus), and 29 elk (Cervus elaphus nannodes) were assayed for human monocytic and human granulocytic ehrlichiosis (HGE) by polymerase chain reaction (PCR), DNA sequencing, and serology to determine whether or not cervids are involved in the maintenance of these potential human pathogens in California (USA). The deer were sampled in August to October 1992–95. The 29 tule elk from Point Reyes National Seashore were sampled in August 1997. All deer were seronegative for antibodies to HGE/Ehrlichia equi, while the E. equi seroprevalence among elk was 17%. The 16S rDNA PCR prevalence in deer was 38% (in mule deer and black-tailed deer) for Ehrlichia-like sp. of white-tailed deer, 5% (one black-tailed deer only) for E. equi, and 0% for E. chaffeensis. The PCR prevalence in elk was 0% for Ehrlichia-like sp. of white-tailed deer, 31% for E. equi, and 0% for E. chaffeensis. The E. equi from two positive elk samples was successfully propagated in HL-60 cell cultures. DNA sequencing confirmed that the Ehrlichia-like sp. sequences from deer in California were closely related to sequences reported from white-tailed deer from Oklahoma and Georgia. The E. equi strain from deer and elk resembled other E. equi strains from California. These results suggest that cervids may be important in the natural maintenance of E. equi in California.

Host association and the capacity of sand flies as vectors of lizard malaria in Panama

In this paper the capacity of sand flies (Lutzomyia) as vectors of parasites that cause malaria in anoles (Anolis limifrons) in the Zona de Canal, Panama was investigated. Inhabiting all study plots, often in local abundance, L. trinidadensis emerged as the principal candidate sand fly vector; the results of surveys did not suggest a likely mosquito vector. Although L. trinidadensis and infected anoles co-inhabited all plots, their abundances seemed unrelated. No evidence that sand flies parasitized anoles was uncovered. As anole activity patterns in daylight reciprocate with those of sand flies and at night anoles seem to avoid locations that sand flies frequent, anoles may evade sand fly bites altogether. Further, these sand flies occurred in close numerical and ecological association with Thecadactylus rapicauda, a reclusive moist forest gecko, often parasitizing these hosts in large numbers. Thus, sand flies lack capacity as vectors of malaria-causing parasites in central Panamanian anoles.

Ectoparasites of the Island Fox on Santa Cruz Island

The ectoparasite fauna for island foxes (Urocyon littoralis) on Santa Cruz Island (California, USA) in April (wet season) and September (dry season) 1998 was evaluated. Three taxa of ectoparasites were identified. These were fleas (Pulex irritans), lice (Neotrichodectes mephitidis), and ticks (Ixodes pacificus). Ectoparasite abundances varied seasonally. Typical of insular endemic species, island foxes may be especially vulnerable to the introduction of novel disease organisms and their vectors.

Compatibility of two species of Ixodes ticks with murid hosts and its effect on transmission of Lyme disease spirochaetes

Prevalence of infection with Lyme disease spirochaetes (Bomlia burgdorferi Johnson ef al.), in adult western black-legged ticks (Ixodes pac

Ectoparasites of a Threatened Insular Endemic Mammalian Carnivore: The Island Spotted Skunk

cus Coley & Kohls, Acari: Ixodidae) ranges in California between 0 and 6%. This differs markedly from that of black-leg@ ticks in New England, I d s scapuloris Say = dmnmini Spielman. et al. (Oliver et al., 1993), 5&70% of which may be infected locally (Burgdorfer et al., 1985; Piesman et af . , 1986). Host relationships of larval and nymphal stages of these ticks underlies this striking difference in tick infection rates. In New England, where white-footed mice, Peromyscus leucopus (Rafinesque), serve as highly competent reservoirs of spirochaetes and as hosts for larvae and nymphs of I.scapularis, numerous cases of human Lyme disease occur annually (Wilson & Reeder, 1993; Steere, 1989; Donahue et al., 1987; Levine er al., 1985). In contrast, nymphal Lpacificus rarely appear on any murid rodent in Northern California (Lane & Loye, 1989,1991; Lane, 1990a; Brown & Lane, 1992), where far fewer human cases occur (CDC, 1993). Indeed, a vertebrate must host two stages of ticks to be a reservoir of an lxodes-transmitted infection (Spielman & Kimsey, 1991). Association of infected Ixodes nymphs with murid hosts of larvae would seem to mediate human risk of Lyme disease. Nymphal I.pacz

DEET (N,N-Diethyl-meta-toluamide) Induced Delay of Blowfly Landing and Oviposition Rates on Treated Pig Carrion (Sus scrofa L.)

cus in California may innately be poor parasites of murid hosts, or an ecological disassociation may separate these organisms. Compared to New England, a much wider range of murids abundantly inhabit California coastal foot-hill habitats where most west coast human Lyme disease occurs (Wilson & Reeder, 1993). It would seem reasonable that nymphs must be encountered by mice but do not often attach or are quickly rejected by these hosts. We might additionally expect I.paci

Insect biodiversity of the Algodones Dunes of California

cus to be poor vectors of zoonotic disease agents between these types of rodents. For example, larval 1.paciJicus acquire spirochetes much

Novel Biology for Tephrochlamys rufiventris (Meigen, 1830) (Diptera: Heleomyzidae)

Abstract Parasites have been identified as potential threats to mammalian carnivores, particularly insular species. We evaluated external parasites on island spotted skunks (Spilogale gracilis amphiala), a threatened insular endemic carnivore on Santa Cruz and Santa Rosa Islands of the California Channel Islands (USA). We identified fleas (Pulex irritans, Nosopsyllus fasciatus), lice (Neotrichodectes mephitidis) and ticks (Ixodes pacificus, I. kingi). Results suggest potential host-switching by ectoparasites among the native and introduced fauna on the islands, possibly due to the paucity of both potential hosts and ectoparasite species. Sharing of ectoparasites enhances the possibility of disease transmission between carnivores via ectoparasite vectors.

Ixodes pacificus (Acari: Ixodidae) as a Vector of Ehrlichia equi (Rickettsiales: Ehrlichieae)

Abstract:  The question of whether the insect repellent N,N‐Diethyl‐meta‐toluamide (DEET) affected fly attraction, oviposition, and larval development was investigated; in part, to determine whether the common habit of wearing DEET as a repellent could affect the rate of human decomposition. Experiments using pig surrogates of human decedents were carried out in a rural environment. Dead piglets were sprayed with DEET, and fly behavior, colonization levels, and maggot development were compared with those in nonsprayed controls. Piglets treated with DEET experienced significant delays in fly visitation and oviposition and delayed appearance of each larval instar, as well as reduced total larval numbers (p < 0.01 for all variables), with subsequently reduced decomposition (p < 0.05). Such changes in fly behavior and larval population development would significantly impact the estimation of the period following the death from entomological evidence in decedents wearing DEET at the time of their death.