Period Of Insect Activity Research Articles

The Effects of Photoperiod on Diapause Induction in Hypena opulenta (Lepidoptera: Erebidae), a Biological Control Agent Against Invasive Swallow-Worts in North America.

Many insects exhibit a short-day diapause response, whereby diapause is induced when daylength falls below a critical threshold. This response is an adaptation to ensure synchrony between periods of insect activity, and the availability of resources, but it can cause problems when organisms are moved to new locations, where early or late-induced diapause can prove a barrier to establishment. We explored the role of photoperiod in diapause induction in Hypena opulenta, a recently introduced classical biological control agent for invasive swallow-worts in North America. We conducted four experimental cage releases as well as a growth chamber experiment to determine the threshold photoperiod for diapause induction in H. opulenta. We determined that the critical photoperiod for inducing diapause in 50% of H. opulenta is 15 h 35 min, which the moth only experiences in the Ottawa release site around summer solstice. This may lead to univoltinism, premature diapause, and poor establishment at some North American release sites. Our results can inform practical aspects of the biological control program for H. opulenta, such as fine-tuning methodologies for stockpiling diapausing pupae in the laboratory and narrowing down the optimal time window for releases at a given location. Additionally, our results will be important for the development of a temperature-based phenology model to more accurately predict voltinism in H. opulenta across the invasive range of swallow-worts in North America.

Forensic entomology for the investigator

AbstractForensic entomology is a discipline deeply rooted in history that is still evolving with regards to its utility in both the modern scientific community and medicolegal death investigations. While there are many applications of forensic entomology with the forensic sciences, the most common application is that of the estimation of time since death, also often known as a minimum postmortem interval, which in some instances can be equal to the time of colonization. This time estimation is based on the period of insect activity on a body, and the age of the insects collected from the remains can aid in determining a portion of the postmortem interval. For this estimation, temperature is a key element of entomological evidence collection, along with the insects themselves. Proper documentation of the scene conditions in which the body is discovered is essential for use in an entomological postmortem interval estimation. Likewise, proper documentation and collection of the insects from the body and the death scene—including a representative sample of all areas of colonization and species present—better allows the entomologist to provide a more accurate and useful estimation of time since death.This article is categorized under:Forensic Biology > Interpretation of Biological EvidenceForensic Anthropology > Time Since Death EstimationForensic Science in Action/Crime Scene Investigation > Crime Scene Examination

A Preliminary Study of Carrion Insects and Their Succession in Luanda, Angola.

The study of the arthropod fauna involved in carcass decomposition is crucial for medicolegal forensic purposes. This knowledge is especially needed in countries with high levels of criminality and where the arthropod fauna is still under-recorded and not well known, such as Angola. We present data from the first survey on sarcosaprophagous flies and beetles in Angola, conducted in Luanda over a 17-d period, in the wet summer season. In total, 881 adult and immature specimens, belonging to 18 species, were collected from three pig carcasses that were sampled daily. Three species were not previously known from Angola. The dominant flies were Chrysomya albiceps (Wiedemann, 1819) (Diptera: Calliphoridae) and Chrysomya megacephala (Fabricius, 1794), but Chrysomya marginalis (Wiedemann, 1830), Chrysomya putoria (Wiedemann, 1830), and Liosarcophaga emmrichiana (Lehrer, 2002) (Diptera: Sarcophagidae) also bred on the carcasses. The dominant beetles were Dermestes maculatus De Geer, 1774 (Coleoptera: Dermestidae), Saprinus splendens (Paykull 1811) (Coleoptera: Histeridae), and Necrobia rufipes (De Geer, 1775) (Coleoptera: Cleridae). Because of the hot weather during the experimental period (~27°C), decomposition was extremely fast. Periods of insect activity on carcasses are presented and comparisons are made with other carrion communities reported from the Afrotropical region.

Molecular differentiation of Central European blowfly species (Diptera, Calliphoridae) using mitochondrial and nuclear genetic markers

A challenging step in medical, veterinary and forensic entomology casework is the rapid and accurate identification of insects to estimate the period of insect activity (PIA), which usually approximates the post-mortem interval (PMI). The morphological identification of insect evidence is hampered by species similarities, especially at the early larval stages. However, DNA-based species identification is more accurate and reliable. In this study, we improved the suitability and efficacy of the standard mitochondrial cytochrome c oxidase subunit I (COI) barcode region of 658bp combined with an additional region of 616bp of the same gene. We also tested the usefulness of other mitochondrial and nuclear loci, such as the non-coding region included in mitochondrial Cyt-b-tRNAser-ND1 (495–496bp) and the second internal transcribed spacer (ITS2) region of nuclear ribosomal DNA (rDNA) (310–337bp). We classified a total of 54 specimens from five blowfly species belonging to three Calliphoridae genera commonly found in Central Europe: Phormia (P. regina), Calliphora (C. vicina) and Lucilia (L. sericata, L. ampullacea and L. caesar). Additionally included were the Cyt-b (307bp) sequences for P. regina species and GenBank recorded information about the studied loci for select species. The results revealed the robustness of COI (616bp) and ITS2 (310–337bp) as diagnostic tools to be added to the widely established COI barcode (658bp). Their higher discriminatory power allows for more precise and reliable identifications, even within more complex genera (Lucilia). This work also contributes new nucleotide sequences that are useful for accurate species diagnosis and new sequence data of Calliphoridae interspecific variability in the European Westphalia region (Germany).

Reply: On Throwing out the Baby With the Bathwater: A Reply to Wells

Dr. Wells' letter to the Editor states that the postcolonization Interval (PCI) and period of insect activity (PIA), as defined in Tomberlin et al. (2011), were esoteric and impracticable concepts. Wells then stated that many researchers were incorrectly using the terms in recent articles and cited our article (Michaud et al. 2012) as an example, along with several others (Mondor et al. 2012, Tomberlin et al. 2012, Berg and Benbow 2013, Bygarski and LeBlanc 2013, Picard et al. 2013). Here, we comment on Wells' assessment of PIA and PCI and we clarify why a citation to Tomberlin et al. (2011) appeared in the introduction of Michaud et al. (2012). We feel it is important to note that we are not involved in forensic entomology casework. Our views are from a research perspective. Wells' criticism of the PIA and PCI concepts is largely one of semantics. One …

Environmental factors affecting early carcass attendance by four species of blow flies (Diptera: Calliphoridae) in Texas.

As the most common primary colonizer of carrion, adult blow flies (Diptera: Calliphoridae) play an important role in initiating arthropod-mediated breakdown of soft tissue; however, their timing is highly variable. This variability complicates the estimation of precolonization intervals or periods of insect activity by forensic entomologists. In this study, the size of the adult blow fly on swine carcasses was compared with various environmental conditions including time of day, temperature, wind speed, and light levels. Four trials were conducted: two in August and September 2008, one in January 2009, and one in February-March 2010. Of the measured variables, time of day was the only consistent factor explaining the population size of blow fly on a carcass, although precipitation and high winds affected winter-active Calliphora vicina Robineau-Desvoidy. Male flies were also collected, suggesting that carcasses may play additional roles in adult blow fly ecology beyond that of a simple oviposition site. For both sexes of flies, a strong diel pattern of behavior emerged, which could be useful in estimating precolonization intervals by considering the environmental conditions at a scene, and thus forensic entomologists may be better able to estimate the likelihood of adult activity at a carcass.

Development of the gregarious ectoparasitoid Nasonia vitripennis using five species of necrophagous flies as hosts and at various developmental temperatures

AbstractThe utility of five species of necrophagous flies (Diptera) as pupal hosts for Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae) was examined by comparing incidences of parasitism, fecundity, and several features of wasp development at three rearing temperatures. Species differences in host suitability were evident in all life history features examined, with the highest incidences of parasitism, largest clutches and adult body sizes, and shortest periods of development occurring when the sarcophagid Sarcophaga bullata Parker served as hosts, regardless of temperature in which the wasps developed. Puparia of the calliphorids Lucilia illustris Meigen, Phormia regina Meigen, and Protophormia terraenovae Robineau‐Desvoidy were also accepted as hosts by the female parasitoids, albeit not equally so, and each yielded large, female‐biased broods. By contrast, pupae of the calliphorid Chrysomya rufifacies (Macquart) were not well suited to serve as an oviposition site or support the development of N. vitripennis. When successful parasitism did occur on any host species, duration of parasitoid development increased, adult body sizes were truncated, male‐biased sex ratios were produced, and mortality from egg hatch to adult emergence elevated with increasing rearing temperature. Unlike with the four other fly species, C. rufifacies did not yield any adult parasitoids when the rearing temperature was 35 °C. The results argue that developmental data determined for this wasp derived from a single host species is not sufficient for applying to all scenarios in which wasp development is necessary to estimate a postmortem interval or periods of insect activity.

ENG

The area of forensic entomology has developed to become an increasingly important aspect of forensic science. Insect larvae and adult insects found on human corpses can provide crucial information for the post-mortem interval (PMI) estimation. In July 2010, a decomposing female corpse was found in Xiangjiang River of Changsha section. The main larvae found on the corpse were identified to be Boettcherisca peregrina (Robineau-Desvoidy) by morphologic observation and were then confirmed by mitochondrial DNA sequence. Based on the experimentally obtained entomological evidence, PMI of the female was concluded between 90 and 120 hours. However, eyewitness reports finally confirmed that the elapsed time since death were 128 hours. This case indicates that PMI estimation in terms of the period of insect activity (PIA) is very complicated and concern many factors such as insect species characteristics, weather and seasonality, geographic region. The interaction between forensic entomologists and pathologists in death cases where insects are associated with remains should be encouraged. Key W ords: forensic science, forensic entomology, post-mortem interval, Boettcherisca peregrina, drowning, mitochondrial DNA.

Environmental Factors Associated With <I>Phormia regina</I> (Diptera: Calliphoridae) Oviposition

The period of insect activity (PIA) contributes information to estimates of the minimum postmortem interval in forensic investigations and begins with blow fly attraction and oviposition on a resource such as carrion or a human corpse. Incorrectly estimating nocturnal oviposition could alter PIA estimates by up to at least 12 h; however, the extent of this difference in PIA would depend on environmental and geographic factors. To date, the literature on the extent and frequency of blow fly nocturnal oviposition is conflicting. Our objectives were as follows: 1) to measure the effects of artificial lighting and beef liver bait height above ground on nocturnal and diurnal oviposition, and 2) to monitor oviposition through the night on swine carcasses exposed to the environment at dusk in different habitats over 3 yr. We documented no consistent nocturnal oviposition in any trial using beef liver or on carcasses in different habitats and seasons. There were statistically significant effects of light and height of bait above the ground on diurnal oviposition of Phormia regina (Meigen) in August of 2009, the only month with mean night temperatures > 20 degrees C. In August there also was significantly greater diurnal oviposition on liver bait placed on the ground compared with bait elevated 1 m. Our results suggest that nocturnal oviposition is rare in the natural environment. However, we found enhanced diurnal oviposition of P. regina under conditions of ambient temperatures > 20 degrees C the night before oviposition. Additional studies are needed to better understand the ecological mechanisms governing blow fly oviposition important to forensic entomology.

Oviposition Restraint and Developmental Alterations in the Ectoparasitic Wasp,Nasonia vitripennis, When Utilizing Puparia Resulting From Different Size Maggot Masses ofLucilia illustris,Protophormia terraenovae, andSarcophaga bullata

Adult females of the ectoparasitoid Nasonia vitripennis (Walker) are capable of distinguishing between hosts of different quality, and then correspondingly adjust clutch sizes and sex ratios of the offspring. In this study, we examined whether the size of the maggot mass, and presumably the developmental temperature, influenced the suitability of the resulting fly pupal and pharate adult stages as hosts for N. vitripennis. Three sizes of maggot masses (100; 500; and 1,000 individuals per mass) were selected for use to generate hosts based on previous studies characterizing developmental and heat shock response differences for the flies. For all host species tested (Lucilia illustris, Protophormia terraenovae, and Sarcophaga bullata), the rate of parasitism by N. vitripennis decreased with increasing maggot mass size. When successful parasitism did occur, parasitoid development increased in duration, clutch sizes decreased, mortality from egg hatch to adult emergence elevated, male biased sex ratios were produced, and adult wasp body sizes were truncated with increasing fly larval density. These wasp life history features are consistent with reductions in host quality. Host quality reductions corresponded to production of heat shock proteins 23, 60, and 70. Heat shock protein synthesis appeared to occur at the expense of normal protein production because total hemolymph protein concentrations decreased with increased larval density in maggot masses. These observations argue that use of N. vitripennis in criminal investigations to estimate periods of insect activity or a minimum post mortem interval must take into account the maggot mass history of the hosts used by the wasp.

Assessment of Decomposition Studies Indicates Need for Standardized and Repeatable Research Methods in Forensic Entomology

The National Research Council (NRC) released a report in 2009 discussing the “science” used in forensics. Specifically, the report outlined concerns regarding the state of the forensic sciences and what was needed to raise the level of rigor and reliability of these fields in a court of law. In response to this NRC document, the present paper examined several parameters used in decomposition studies that have implications for forensic entomology. Specifically, this analysis was conducted to determine the degree of repeatability in methods across studies as related to general conclusions drawn in court, entomology and forensic investigations. Forensic entomologists primarily analyze insect evidence recovered from decomposing remains to estimate a portion of the Period of Insect Activity (PIA), which encompasses the time of colonization, to infer a minimum Postmortem Interval (PMI). One method utilized by entomologists relies on succession data from published studies to generate estimates of the minimum PMI of a decedent. For this article, approximately 75 publications on arthropod succession on vertebrate carrion were reviewed for 13 criteria that are known to play instrumental roles in governing this process: 1) animal model, 2) time of actual death, 3) euthanasia method, 4) storage method, 5) storage time, 6) time of removal from storage to placement in the field, 7) time of day remains placed in the field, 8) catalog of arthropods associated with the remains over time 9) time of initial insect contact, 10) time of initial colonization (i.e., arthropod offspring located on the remains), 11) study site, 12) number of replicate carcasses and 13) months and season of study. These criteria were selected as they can directly impact arthropod colonization and succession patterns on vertebrate carrion and are easily recorded. Data indicated that such information is highly fragmented, and that key criteria necessary to repeat studies (a core principle of the scientific method) are often lacking in the published literature. As an example, among the studies included in this analysis, we could not find significant associations between arthropod taxa richness and carcass model or carcass size. In the case of carcass size, island biogeography theory predicts that larger areas/resources will hold higher diversity. We suspect that the high degree of reporting variability in taxonomic resolution and taxa-specific study focus precluded such relationships that have been reported for other disciplines of biology. Consequently, we suggest that, to date, because of these issues there has not been a comprehensive analysis (e.g., meta-analysis) to provide general inference of arthropod succession patterns on carrion to predict a minimum PMI. In order to begin standardizing such studies, we suggest that future research endeavors examining arthropod succession on carrion record detailed data for all of the suggested criteria. Doing so can result in data amassed over time for use in comprehensive and strong meta-analyses. Such results could allow for greater appreciation of variation associated with arthropod succession on carrion.

A millennial-scale reconstruction of spruce budworm abundance in Saguenay, Quéebec, Canada

A high-resolution macrofossil analysis was conducted to reconstruct spruce budworm abundance in an 8600-year-old mire in Saguenay, Québec, Canada. Abundant spruce budworm (Choristoneura fumiferana [Clem.]) faeces recovered in the peat profile suggested endemic and epidemic presence of the insect in the study site since 8240 cal. BP. Important variations in the abundance of faeces were observed, and two exceptional periods of insect activity were delineated, from 6815 to 6480 cal. BP and during the twentieth century. Lepidoptera head capsules were also found in the Lac des Îlets peat profile. They were less abundant and more altered than spruce budworm faeces, but they offered complementary information on insect activity. The long-term perspective achieved with this macrofossil analysis strongly suggests that intense periods of spruce budworm activity were rare events during the Holocene.

SEASONAL OCCURRENCE OF LYGUS SPP. (HETEROPTERA: MIRIDAE) ON ALFALFA IN SASKATCHEWAN

Several species of Lygus (Hahn) that occur in Saskatchewan are serious and continuing pests of alfalfa grown for seed. They are readily controlled by any one of several insecticides, but the efficiency of this control is dependent upon knowing their seasonal development and occurrence on the crop.In the years 1976 and 1978, at three locations in Saskatchewan, populations of Lygus in alfalfa seed crops were sampled at 5- to 7-day intervals throughout the period of insect activity. In 1979 and 1980 samples of bugs were taken occasionally from the same locations, and in all years from other locations in the province. A sample consisted of 0–700 specimens collected by either a 38-cm sweepnet in not less than 25 and as many as 200 random sweeps, or a D-Vac sampler in not less than 3 m2 in spring and after harvest when sweep-sampling was not possible. Collected specimens were preserved in alcohol, sorted, and identified. Additional data, not previously published, were available from a similar mid-1950's study of Lygus seasonal occurrence in alfalfa seed crops in the Torch River district of northeastern Saskatchewan.

Response of Soybeans to Foliage Losses in South Carolina1

Defoliations of 17, 33, 50, and 67% were made during periods of insect activity on soybeans at midbloom, pod-set, pod-fill, and on a continued basis from midbloom to pod-set. Foliage losses of 33% at bloom did not result in significant yield losses in any of 10 tests; 67% defoliation at pod-set, or on a continued basis from bloom to pod-set caused greatest losses; and 17% defoliation did not cause significant losses at any stage of growth or on a continued basis. Yield losses from defoliations at pod-fill were intermediate between those at bloom and pod-set. Yield reductions were generally accompanied by reductions in seed weight and protein content and increases in oil content. Seed germination was not affected. Although results were not affected significantly by date of planting and by use of irrigation or different varieties, there was a tendency toward generally lower yields at high production levels in the ‘Hampton’ variety after severe defoliations (50 and 67%) at bloom and pod-fill. It was concluded that foliage losses of 17 or 33% allowed additional light penetration to lower leaves, resulting in compensation by increased photosynthate production in these leaves.