Blow Flies Visiting Decaying Alligators: Is Succession Synchronous or Asynchronous?

Abstract

Succession patterns of adult blow flies (Diptera: Calliphoridae) on decaying alligators were investigated in Mobile (Ala, USA) during August 2002. The most abundant blow fly species visiting the carcasses were Chrysomya rufifacies (Macquart), Cochliomyia macellaria (Fabricus), Chrysomya megacephala (Fabricus), Phormia regina (Meigen), and Lucilia coeruleiviridis (Macquart). Lucilia coeruleiviridis was collected more often during the early stages of decomposition, followed by Chrysomya spp., Cochliomyia macellaria, and Phormia regina in the later stages. Lucilia coeruleiviridis was the only synchronous blow fly on the three carcasses; other blow fly species exhibited only site-specific synchrony. Using dichotomous correlations and analyses of variance, we demonstrated that blow fly-community succession was asynchronous among three alligators; however, Monte Carlo simulations indicate that there was some degree of synchrony between the carcasses.

Behavioral Patterns of Adult Carrion Flies Phormiaregina and Luciliacoeruleiviridis (Diptera: Calliphoridae) at Pig Carcasses in West Virginia, USA.

“…Moreover, L. coeruleivirids consistently makes up the "first arrivals" (within the first 24 h after death) on a variety of other carcass substrates from disparate geographic locales in the U.S.: rats, rabbits and sheep in California (Denno and Cothran 1975); rabbits, opossums and largemouth bass in Mississippi (Goddard and Lago 1985); chickens in Missouri (Hall and Doisy 1993); squirrels, rabbits, cat, opossum in Illinois (Johnson 1975); alligators in Alabama (Nelder et al 2009); and dogs in Tennessee (Reed 1958). We found that L. coeruleiviridis arrived at carcasses early, but their numbers diminished over time, being supplanted by P. regina adults.…”

The Role of Spatial Aggregation in Forensic Entomology: Table 1.

“…Once diversity patterns have been identiÞed, a more concerted and detailed effort can be made into the mechanisms that structure these patterns. For example, the evidence showing that 1) insect successional patterns lack discrete boundaries between colonizing taxa (Schoenly and Reid 1987, Boulton and Lake 1988, Moura et al 2005, Nelder et al 2009) and 2) manipulating the time of exposure does not alter time of colonization for putatively primary species (Lang et al 2006) provides only limited support for the hypothesis that interspeciÞc competition has resulted in the evolution of resource partitioning along a temporal gradient. Similarly, the evidence showing random spatial associations between species, which has been reported in other patchy systems, provides limited support for resource partitioning along a spatial gradient (Shorrocks et al 1990, Inouye 1999, Toda et al 1999, Werthem et al 2000, Krijger and Sevenster 2001, Woodcock et al 2002, Takahashi 2006.…”

“…We suspect that this limited use could be owing to four potentially interrelated reasons: 1) insect successional patterns have been found to be highly variable at early and intermediate stages, particularly among replicate carcasses (e.g., Lang et al 2006; discussed in Wells and LaMotte 2010; see Fig. 2 in Tomberlin et al 2011a), 2) speciÞc associations of insect assemblages with the physical characteristics of carrion generally do not exist in nature Reid 1987, Boulton andLake 1988), 3) patterns of insect succession lack discrete boundaries between colonizing taxa (Schoenly and Reid 1987, Boulton and Lake 1988, Moura et al 2005, Nelder et al 2009), and 4) PMI estimates based on developmental rates are far more accurate in the earlier PMI. Thus, reasons 1Ð3 would suggest that the ecological underpinnings of the traditional succession-based paradigm may not fully capture all of the ecological factors inßuencing insect colonization on cadavers.…”

The Development of an Insect Succession Model Suitable for Time-Since-Death Statistics

“…Studies repeatedly affirm that insect succession on carrion is "predictable" because of observed consistency of: (1) the sequence of carrion insect arrival , Arnaldos et al 2005 2carrion insect arrival and departure times , and (3) change in community composition ) on carrion exposed under similar conditions. Among similar and simultaneously exposed carcasses, observed variation in succession ranges from negligible , Hobishack 1997, Leblanc and Strongman 2002 to considerable , Nelder et al 2009. Minimal replication preventing the development of a forensically applicable succession dataset was noted ) yet inadequate experimental designs persist .…”

“…Because of these barriers, researchers have chosen to use a range of carcass types including (e.g. guinea pigs , chickens, (Arnaldos et al 2004a), cats (Early and Goff 1986), dogs ), goats (Wells and Greenberg 1994a), impalas (Ellison 1990) and alligators (Nelder et al 2009)). Data collected from non-human decomposition models are used in forensic casework (Goff and Flynn 1991, Turchetto et al 2001, Arnaldos et al 2004b, Olivia and Ravioli 2004), yet relevance of these data is tenuous.…”