50 years later, insect evidence overturns Canada's most notorious case - Regina v. Steven Truscott.

On 11 June 1959, the body of 12-year old Lynne Harper was discovered in a woodlot northeast of Clinton, Ontario. Although insect evidence was photographed and collected at the scene and autopsy, this evidence was not used in the 1959 trial. Instead, time of death was pinpointed to a 45-min window of 1900-1945 h on 9 June 1959 based on stomach content analysis. Based on circumstantial evidence and this time frame that he was the last suspect to see her alive, 14-year old Steven Truscott was convicted of her murder. He was scheduled to be hanged, but a temporary reprieve postponed his execution. In 1960, his death sentence was commuted to life imprisonment. Truscott was the youngest person to be sentenced to death in Canada, and his case provided the major impetus toward abolition of the death penalty in Canada. Truscott always maintained his innocence. In 2001, the Association in Defence of the Wrongly Convicted filed an appeal to have the case reopened. In 2006, the authors of this paper were contacted by Attorneys James Lockyer and Phil Campbell of the LCP Law Firm in Toronto to investigate this case. Fresh evidence was presented at the Ontario Court of Appeal in 2006-2007 including testimony of 3 forensic entomologists. This resulted in controversy regarding identification of the insects and assumptions of insect behaviour that affected the postmortem interval estimate. Lack of scientific evidence for the controversial theories proposed by one testifying entomologist resulted in disregarding his testimony. Instead, testimony by VanLaerhoven and Merritt was accepted. Based on their analysis and a re-creation experiment of the insect evidence, initial fly colonization occurred during daylight hours of 10 June 1959. The collected larvae were not likely to have been deposited on the body before dark (2140 h) on 9 June 1959 as this would have resulted in significantly larger and more advanced larval instar than were collected at the scene or autopsy. This analysis, together with a pathology reanalysis of stomach content analysis, demonstrated that the original estimate of time of death was unreliable. Truscott was with numerous witnesses prior to 1900 h and after 2000 h on 9 June 1959, thus the estimate of time of death was the most critical evidence in the original 1959 trial and the 2006-2007 appeal. On 28 August 2007, his conviction was overturned, declared a wrongful conviction and miscarriage of justice. Steven Truscott was acquitted of the murder charges.

Effect of Temperature on Oviposition Behavior and Egg Load of Blow Flies (Diptera: Calliphoridae).

Making optimal oviposition decisions is especially important for female carrion colonizing insects whose larvae often depend on ephemeral resources. Optimal oviposition theory predicts that females should exhibit behaviors that will maximize the performance of their offspring. Oviposition can be influenced by a variety of factors, including temperature. The aim of this study was to investigate the effects of temperature on the oviposition behavior and egg load of two blow fly species native to southern Ontario: Phormia regina Meigen, and Lucilia sericata Meigen (Diptera: Calliphoridae). Using fetal pig carcasses as an oviposition substrate, we assessed the length of time until the first oviposition event, preferred oviposition sites, and the total number of eggs oviposited. For each of the two species, five different temperature treatments ranging from 15 to 35°C were used. Temperature influenced time to the first oviposition event, as well as the number of eggs deposited by L. sericata and P. regina. As temperature increased, oviposition occurred faster with more eggs deposited for these two species. Female P. regina, in particular, demonstrated a higher egg load with increasing temperature. Differences in optimal temperatures for reproduction, including egg load and oviposition, may be a mechanism driving seasonal temporal resource partitioning leading to species coexistence utilizing ephemeral resources.

The Relationship Between Surface Area and Volume of Common Blow Fly (Diptera: Calliphoridae) Oviposition Sites and Carrion Body Mass.

Female blow flies (Diptera: Calliphoridae) demonstrate site preferences when ovipositing on carrion. Preference for oviposition sites is believed to reflect the suitability of the site such that the most preferred locations provide offspring with the greatest chance of survival. A number of factors might influence female choice, including area available for oviposition. For species known to aggregate during oviposition, the surface area of oviposition sites may be a key factor in the decision-making process. Using ImageJ, the surface area or volume of eight common oviposition sites on 13 fetal pig (Sus scrofa domesticus L.) carcasses was measured. Regression analysis was used to determine if body mass could predict the area or volume available for oviposition. We observed significant positive relationships between size of oviposition sites and body mass for all eight oviposition sites. The strongest relationships were observed for the face (R2 = 0.86) and legs (R2 = 0.84). To test the predictive capacity of this relationship, a blind validation study was performed. Five pigs of various body masses were randomly selected, and the available space of the eight sites was estimated using the regression equations. The validation study confirmed that the regression equations for most oviposition sites demonstrated their predictive capacity based on 95% prediction intervals. This research provides a tool that can be used to correct for differences in oviposition site area or volume between carcasses of varying mass so that researchers may gain a greater understanding of the oviposition preferences and aggregation behaviors in future studies.

Estimating the Number of Eggs in Blow Fly (Diptera: Calliphoridae) Egg Masses Using Photographic Analysis.

Little work has been done to quantify the number of eggs oviposited by blow flies (Diptera: Calliphoridae) in studies examining colonization behavior. Egg counting methods currently available are time-consuming and destructive. This study used ImageJ software and analysis of covariance to relate the volume of egg masses to the number of eggs laid by three different blow fly species: Lucilia sericata (Meigen), Phormia regina (Meigen), and Chrysomya rufifacies (Macquart). Egg mass volume, species, and the interaction of species and egg mass volume all affected the number of blow fly eggs deposited in egg masses. Both species identity and egg mass volume are important when predicting egg number, as such a single regression equation cannot be used to estimate egg number for these three species. Therefore, simple linear regression equations were determined for each species. The volume of individual eggs was incorporated into the model, yet differences between species were observed, suggesting that the orientation of the eggs oviposited by multiple conspecific females within egg masses influences egg estimates. Based on our results, we expect that imaging software can be used for other blow fly species, as well as other insect species; however, equations specific to each species must be developed. This study describes an important tool for quantifying egg deposition in a nondestructive manner, which is important in studying the colonization behavior and life history of insects of ecological and forensic importance.

Substrate effects on pupation and adult emergence of Hermetia illucens (Diptera: Stratiomyidae).

Black soldier flies, Hermetia illucens (L.) (Diptera: Stratiomyidae), are of particular interest for their applications in waste management. Feeding on decaying organic waste, black soldier flies successfully reduce manure in confined animal feeding operations of poultry, swine, and cattle. To optimize waste conversion in confined animal feeding operations and landfill facilities, it is imperative to optimize black soldier fly development. Unfortunately, black soldier flies only convert waste during their larval feeding stages and therefore it is of interest to optimize the nonfeeding stages of development, specifically, the postfeeding and pupal stages. The time spent in these stages is thought to be determined by the pupation substrate encountered by the postfeeding larvae. The objective of this study was to determine the effect different pupation substrates have on postfeeding development time, pupation time, and adult emergence success. Five pupation substrates were compared: wood shavings, potting soil, topsoil, sand, and nothing. Postfeeding larvae took longer to reach pupation in the absence of a pupation substrate, although reaching pupation in the shortest time in potting soil and wood shavings. The time spent in the pupal stage was shortest in the absence of a pupation substrate. However, fewer adults emerged when a pupation substrate was not provided.

Investigating the diet of the omnivorous mirid Dicyphus hesperus using stable isotopes.

Omnivory involves numerous feeding relationships and a complex web of interactions. When using omnivores in biocontrol, these interactions need to be understood to maximize feeding on the target species and minimize non-target interactions. Dicyphus hesperus is used along with Encarsia formosa for biocontrol of whiteflies in greenhouse tomato crops. Dicyphus hesperus is a generalist omnivore which feeds on all components of the system. To quantify these interactions, stable isotope analysis was used to identify trophic position with nitrogen isotopes (delta15N) and plant sources with carbon isotopes (delta13C). Feeding trials were used to establish baseline isotopic data for D. hesperus and their diet, including Verbascum thapsus, an alternative plant food. Cage trials were used to monitor population abundances and the isotopic signature of D. hesperus. In feeding trials, D. hesperus were enriched relative to their food, suggesting an elevated trophic position. However, large amounts of isotopic variation were found within all diet components, with only V. thapsus exhibiting a distinct signature. In cage trials, the average delta15N and delta13C of the omnivore declined over time, coinciding with declines in total available prey, though it may be confounded by changes in temperature. The range of delta13C, but not the range of delta15N, also declined over time. This suggests a change in the plant source within the diet, but also some unquantified variability within the population. We suggest that diet variability exists within D. hesperus populations, declining as prey become less abundant.

Blind validation of postmortem interval estimates using developmental rates of blow flies.

This study evaluated the use of different degree day (DD) models, developmental thresholds and developmental data sources for estimating postmortem interval (PMI) based on developmental rates of blow flies (Diptera: Calliphoridae). Blow fly evidence was collected from three mock crime scenes and sent for blind analysis of PMI. PMI estimates were calculated using averaging, single sine, double sine, single triangle, and double triangle models of DD calculation with minimum developmental thresholds of 0, 6 and 10 degrees C and Anderson's, Byrd and Allen's, Greenberg's, Nishida's and Kamal's developmental data sets. These estimates were compared with the actual PMI to determine which combination of DD model, developmental threshold and developmental data provided the most accurate estimate. For all three cases, at least one method gave a PMI estimation that was within 1 day of the actual date of death. There was no variability between PMI estimated using the five models of DD calculation. Overall, as lower developmental threshold increased, the PMI interval estimates increased. Depending on the developmental data set used, increasing the lower developmental threshold caused some overestimations of the date of oviposition, with estimates given that were prior to the actual death. Future PMI estimates should include error ranges, so that overestimation of PMI is avoided.

Insect succession on buried carrion in two biogeoclimatic zones of British Columbia.

We established a database of insect succession on buried carrion in two biogeoclimatic zones of British Columbia over a 16-month period beginning June 1995. Pig (Sus scrofa L.) carcasses were buried shortly after death in the Coastal Western Hemlock and Sub-boreal Spruce biogeoclimatic zones of British Columbia. Buried pigs exhibited a distinct pattern of succession from that which occurred on above-ground carrion. The species composition and time of colonization for particular species differed between the two zones. Therefore ideally, a database of insect succession on buried carrion should be established for each major biogeoclimatic zone. We did not observe maggot masses on any of the buried carcasses; therefore, the presence of maggot masses may indicate a delayed burial. Soil temperature was a better indicator of internal buried carcass temperature (r2 = 0.92, p < 0.0001) than was ambient air temperature (r2 = 0.60, p < 0.0001); thus soil temperature should be used to determine developmental rates of insects for determination of the postmortem interval by a forensic entomologist.