The pre-appearance interval (PAI) is an interval preceding appearance of an insect taxon on a cadaver. It decreases with an increase in temperature in several forensically-relevant insects. Therefore, forensic entomologists developed temperature methods for the estimation of PAI. In the current study these methods were tested in the case of adult and larval Necrodes littoralis (Coleoptera: Silphidae), adult and larval Creophilus maxillosus (Coleoptera: Staphylinidae), adult Necrobia rufipes (Coleoptera: Cleridae), adult Saprinus semistriatus (Coleoptera: Histeridae) and adult Stearibia nigriceps (Diptera: Piophilidae). Moreover, factors affecting accuracy of estimation and techniques for the approximation and correction of predictor temperature were studied using results of a multi-year pig carcass study. It was demonstrated that temperature methods outperform conventional methods. The accuracy of estimation was strongly related to the quality of the temperature model for PAI and the quality of temperature data used for the estimation. Models for larval stage performed better than models for adult stage. Mean temperature for the average seasonal PAI was a good initial approximation of predictor temperature. Moreover, iterative estimation of PAI was found to effectively correct predictor temperature, although some pitfalls were identified in this respect. Implications for the estimation of PAI are discussed.
Insects regulate their body temperature mostly behaviourally, by changing posture or microhabitat. Usually they use heat that is already present in the environment. Sometimes, however, they may manipulate the environment to affect, focus or benefit from thermogenesis. Carrion beetles create a feeding matrix by applying to cadaver surface anal or oral exudates. We tested the hypothesis that the matrix, which is formed on carrion by communally breeding beetle Necrodes littoralis L. (Silphidae), produces heat that enhances insect fitness. Using thermal imaging we demonstrate that heat produced in the matrix formed on meat by adult or larval beetles is larger than in meat decomposing without insects. Larval beetles regularly warmed up in the matrix. Moreover, by comparing matrix temperature and larval fitness in colonies with and without preparation of meat by adult beetles, we provide evidence that formation of the matrix by adult beetles has deferred thermal effects for larval microhabitat. We found an increase in heat production of the matrix and a decrease in development time and mortality of larvae after adult beetles applied their exudates on meat in the pre-larval phase. Our findings indicate that spreading of exudates over carrion by Necrodes larvae, apart from other likely functions (e.g. digesting carrion or promoting growth of beneficial microbes), facilitates thermoregulation. In case of adult beetles, this behaviour brings distinct thermal benefits for their offspring and therefore may be viewed as a new form of indirect parental care with an important thermal component.
Large carrion is inhabited by highly variable and interactive communities of insects. Positive interactions in carrion insect communities have been recently the focus in carrion ecology. By contrast, competition between carrion insects is rather undervalued. Here we provide evidence that blow flies (Calliphoridae) and Necrodes beetles (Silphidae), dominant decomposers of large carcasses in terrestrial habitats, compete over carrion. By reanalysing the results from 90 pig carcasses we demonstrated that the contribution of the flies and the beetles to the decay was negatively related. The greater part of the large carrion pool was monopolised by blow flies, whereas Necrodes beetles abundantly colonized carcasses, on which blow flies were less effective as decomposers. In behavioural assays, we found that adult beetles killed four times more frequently feeding than postfeeding third instar larvae of the flies, with the large decrease in the killing frequency after the larvae reached the age of early third instar. Therefore, adult Necrodes beetles preferentially killed the larvae that were before or in their peak feeding. The study provides evidence that the interaction between blow flies and Necrodes beetles is a combination of indirect exploitative effects of the flies and direct interference effects of the beetles (the mixed competition).
The estimation of postmortem interval (PMI) based on successional patterns of adult insects is largely limited, due to the lack of potential PMI markers. Sex and size of adult insects could be easily used for such estimation. In this study, sex- and size-related patterns of carrion attendance by adult insects were analyzed in Necrodes littoralis (Coleoptera: Silphidae) and Creophilus maxillosus (Coleoptera: Staphylinidae). For both species, abundance of males and females changed similarly during decomposition. A slightly female-biased sex ratio was recorded in N. littoralis. Females of N. littoralis started visiting carcasses, on average, one day earlier than males. There was a rise in size of males of N. littoralis at the end of decomposition, whereas for females of both species and males of C. maxillosus, no size-related patterns of carrion visitation were found. Current results demonstrate that size and sex of adult carrion beetles are poor indicators of PMI.
14Insects regulate their body temperature mostly behaviorally, by changing posture or 15 microhabitat. These strategies may be ineffective in some habitats, for example on carrion. 16 Carrion beetles create a biofilm-like matrix by applying to cadaver surface anal or oral 17 exudates. We tested the hypothesis that biofilm formed by communally breeding Necrodes 18 littoralis L. beetles (Silphidae) produces heat, that enhances beetle fitness. We demonstrated 19 that heat produced in the biofilm is larger than in meat decomposing without insects. Beetles 20 regularly warmed up in the biofilm. Moreover, we provide evidence that biofilm formation by 21 adult beetles has deferred thermal effects for larval microhabitat. We found an increase in heat 22 production of a biofilm and a decrease in development time and mortality of larvae, after 23 adult beetles applied their exudates on meat. Behavioral strategy revealed here for N. littoralis 24 is basically a new form of thermoregulation and parental care in insects. 25 26 Keywords 27 Insect thermoregulation; Animal behavior; Parental care; Carrion ecology; Insect-microbe 28 interactions; Resource competition 29 30 31Temperature is a key component of animal environment. Insects usually use external 32 heat to regulate their body temperature (1, 2). By changing body orientation or selecting 33 microhabitat with specific thermal characteristics, insects may maintain their body 34 temperature within thermal optima (3, 4). These mechanisms may be ineffective at certain 35 developmental stages (e.g. larvae) and in some microhabitats (e.g. carrion or dung), indicating 36 that other thermal options may be important for some insect ectotherms. 37Carrion is an example of a "bonanza" resource, i.e. very rich but at the same time 38 scattered and ephemeral (5). There is severe competition between microbes, insects, and 39 vertebrates over carrion resources (6)(7)(8)(9)(10)(11)(12). Insects, e.g. blow flies (Calliphoridae) or carrion 40 beetles (Silphidae) use carrion for breeding and their larvae are main carrion reducers in 41 terrestrial environments (11, 13, 14). Necrophagous larvae usually feed in aggregations (15). 42Larval aggregates on carrion may have much higher inner temperature than ambient air (by 43 10-30°C), an effect originally discovered in aggregations of larval blow flies (4, 16-20). Heat 44 in these aggregates was hypothesized to derive from microbial activity (21, 22), larval 45 exothermic digestive processes (19) or larval frenetic movements (20, 23). However, the 46 specific mechanisms involved are not known. 47 Carrion beetles, in particular burying beetles (Silphidae: Nicrophorus), create a 48 biofilm-like matrix on cadavers by applying to its surface anal and oral exudates (24). In case 49 of Nicrophorus the behavior was hypothesized to moisturize carrion (25), facilitate digestion 50 (25-27), suppress microbial competitors (24, 28-31), deter insect competitors by reducing 51 carrion-originating attractants (25, 32, 33), support larval aggregation (25) or...
Despite widely accepted standards for sampling and preservation of insect evidence, unrepresentative samples or improperly preserved evidence are encountered frequently in forensic investigations. Here, we report the results of laboratory studies on the survival of Lucilia sericata and Calliphora vomitoria (Diptera: Calliphoridae) intra-puparial forms in hermetic containers, which were stimulated by a recent case. It is demonstrated that the survival of blowfly intra-puparial forms inside airtight containers is dependent on container volume, number of puparia inside, and their age. The survival in both species was found to increase with an increase in the volume of air per 1 mg of puparium per day of development in a hermetic container. Below 0.05 ml of air, no insect survived, and above 0.2 ml of air per 1 mg of puparium per day, survival reached its maximum. These results suggest that blowflies reveal a single, general pattern of survival under decreasing oxygen conditions and that this pattern is a product of number of developing insects, their age and the initial amount of available air. Implications for forensic entomology are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.