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1、1,Lesson 9,Forensic Entomology (法醫昆蟲學),2,Activity 9.1 Introduction of Forensic Entomology,Introduction of Forensic Entomology (http:/www.nhm.ac.uk/nature-online/nature-live/video-archive/videos/forensic-entomology/ )(an on-line video by Martin Hall of Natural History Museum of London) (suggested epi
2、sode for video watching: 00:00 - 16:27),3,Taxonomy of insects,Kingdom (界) Animalia (動物界) Phylum (門) Arthopoda (節肢動物門) Class (綱) Insecta (昆蟲綱) Order (目) X, Y, Z Family (科) A, B, C, Genus(種) D, E, F, Species(屬) G, H, I, ,4,Taxonomy of True Flies,Kingdom (界) Animalia (動物界) Phylum (門) Arthopoda (節肢動物門)
3、Class (綱) Insecta (昆蟲綱) Order (目) Diptera (雙翅目) Family (科) Calliphoridae (Blow Flies) Sarcophagidae (Flesh Flies) Genus(種) Species(屬) ,5,True Flies of Hong Kong,6,亞麻蠅 House Fly (Parasarcophage sp.) Source: Hong Kong Insects (2007) (Friends of the Country Parks & Cosmos Books Ltd),Genus name,Species
4、name,7,金蠅 Blow Fly (Chrysomya sp.) Source: Hong Kong Insects (2007) Source: Hong Kong Insects (2007) (Friends of the Country Parks & Cosmos Books Ltd),Genus name,Species name,8,南亞寡鬃實蠅 Pumpkin Fruit Fly (Bactrocera tau) Source: Hong Kong Insects (2007) (Friends of the Country Parks & Cosmos Books Ltd
5、),Genus name,Species name,9,Source: http:/www.padil.gov.au (Pests and Diseases Image Library),Chrysomya megacephala (紅頭麗蠅) (Bluebottle),10,Chrysomya megacephala (Found in HK) Order (目) Diptera (雙翅目) Family (科) Calliphoridae Genus(種) Chrysomya Species(屬) megacephala,11,Pupa 6-10 mm,Egg 2-3 mm,Life Cy
6、cle of a Blow Fly (Complete Metamorphosis),NOT TO SCALE,Adult,Larva,1st instar 2-4 mm,2nd instar 5-8 mm,3rd instar 10-15 mm,Source: http:/www.forensicentomologist.org/,12,Remarks: 1st instar 1 slit within each spiracle 2nd instar 2 slits within each spiracle 3rd instar 3 slits within each spiracle,A
7、 maggot (larval stage),Posterior blunt part (spiracles for breathing),Anterior pointed part (mouth for eating),Two spiracles (each with 3 slits) 3rd instar,13,The puparial case is usually oval in shape and changes colour over time. The colour of the puparial case of different blow fly species varies
8、.,14,Forensic Entomology Kit,Source: http:/ (SIRCHIE),15,PMI (Post Mortem Interval),PMI the time elapsed since death PMI usually correlates with the age of the oldest immature blow fly stage developing on the corpse. Depending on the species of the blow flies and the environment such as ambient air
9、temperature the development of the blow flies may take several weeks or months.,16,A dead body is a rich source for carrion animals which include insects and other arthropods such as beetles.,17,Effect of temperature on the rate of development of insects,Insects (e.g. blow flies) are cold-blooded an
10、imals and their level of activity including the growth rate depends on the temperature of the surrounding environment. Insects require a certain amount of heat energy to develop from one stage in their life cycle to another stage. The heat energy is required for the enzyme-controlled biochemical rea
11、ctions of insects,18,Effect of temperature on the rate of development of insects,For flies to develop the temperature must remain between a minimum temperature (minimum developmental threshold) and a maximum temperature (upper developmental threshold) for a certain amount of time The minimum thresho
12、ld temperature for many fly species = 10oC (generally 6oC to 10oC) On either side of the minimum threshold temperature the insect will not develop or the rate of development will decrease,19,It is found that rate of development of insects is directly proportional to temperature The higher the temp.,
13、 the less time needed for the development of insects,20,21,Accumulated Degree Hours/Days ADH / ADD,Accumulated Heat a combination of temperature above the minimum developmental threshold multiplied by time is measured as physiological time (“physiological energy budget”), in units called degree-days
14、 (o D) or degree-hours (ohr) ADH = (T-Tmin)oC X time (in hr) ADD = (T-Tmin)oC X time (in day),22,Each insect species requires a certain number of degree-days / degree-hours to complete its life cycle The amount of heat energy required for the development of a specific insect species is constant (i.e
15、. the ADD / ADH for development is specific for a certain insect species) The ADH for the blow fly Phormia regina and Sarcophaga bullata are 5160 ADH and 8317 ADH respectively,23,As the temperature increases or decreases, the chemical reactions governing the growth of an insect (blow fly) increase o
16、r decrease correspondingly. However, the total amount of ADH for a blow fly to reach a specific growth stage is the same whether it happens quickly at higher temperature or slowly at lower temperature.,24,For instance, the total ADH for the blow fly Phormia regina to develop from the egg stage to the end of 1st instar = 567.8 ADH If the eggs of the blow fly are reared at 26.7oC, it
