Entomology History PDF

1 Hugh Cuming ENTOMOLOGY HISTORY – pioneer on exploring and collecting in Luzon,...

1 Hugh Cuming ENTOMOLOGY HISTORY – pioneer on exploring and collecting in Luzon, Mindanao, and many smaller islands in the Philippines. Entomology [Greek entamon = “notched” referring to First in 1831 and again in 1840 the segmented body plan of the insect] – science that Carl-Atahl (famous Swedish entomologist) deals with the study of insect and other arthropods. – considered father of modern hemipterology Arthropoda [arthro = joint ; poda = feet] – published Hemiptera Insularum Philippinarum in 1870 a. Insects George Semper (German zoologist) b. Arachnida (spiders, scorpions, mites, ticks) – published Die Schmetterlings de Philippineschen c. Crustacea (shrimp, lobster, pillbugs) Inseln: Rophalocera (1868-1902) d. Xiphora (horseshoe crabs) e. Diplopoda (millipedes) Shultze’s (1928) f. Chilopoda (centipedes) – claimed that the works of Carl-Atahl and George Semper are milestone of Philippine entomology Medical Entomology – medical science directly because the Hemiptera and Lepidoptera are the best concerned with arthropods that affects health and well- known order in the Philippines with 1,825 recorded being of man and vertebrate animals. species Industrial/Encomical Entomology – deals with Baron Edmond de Seyls-Longchamps (French) industrially or economically important arthropods – world authority on dragonflies and damselflies in his (industrial pets) time Agricultural Entomology – agricultural pest science – published Odonates des Philippines in 1991 dealing with arthropods that affect plants and animals Ramon Jordana 1909 – foundation of College of Agriculture at Los Banos – published Bosquejo geografico e historico-natural del Archipelago Filipino (1885) in Madrid 1910 – foundation of the organization of an entomological section in the Bureau of Agriculture, Father Castro de Elera (Dominican) Manila – published Catalogo Sismatico de toda la fauna de Filipinas cococida hasta el presente, 3 volumes (1895- 1896), University of Santo Tomas Press, Manila. PROMINENT PERSONALITIES Domingo Sanchez y Sanchez( assistant zoologist of Aristotle (Greek philosopher and scientist) government forestry services) – provided descriptions of insect anatomy in 4th century – published Memoria Sobre Un insect Enemigto del BCE which laid the groundwork of modern entomology Cofeto ( 1890) which is about coffee long-horned bore Ulisse Aldrovandi (Italian naturalist) Francisco Alcarraz (Spanish colonist 1895) – published De Animalibus Insectis or “Of Insect – not an entomologist, however, proved himself a Animals” in 1602 careful and accurate observer of insect particularly on migratory locust and silkworms Jan Swammerdam (Dutch naturalist) – observe the minute structures of many insect species Charles S. Banks which began the modern insect classification in 18th – appointed as the first Government entomologist in century the Philippines in 1920 to organize the entomological section Bureau of Government Laboratories (Later René-Antoine Ferchault de Réaumur (Fresh biologist ) Bureau of Science) – published the first of six volumes of Mémoires pour – initiated research activities on insects of medical server à l’histoire des insects or “Memoirs Serving as a importance History of Insects” in 1734 Charles Fuller Baker Carolus Linnaeus – professor of agronomy and subsequently dean of the – applied his system of binomial nomenclature to College of Agriculture from 1912 until his death in 1972 organize the classification of insect species in Systema Naturae (10th ed., 1758). Julian Valdez (Cuban collector) – paid out by Charles Fuller Baker out of his personal John Curtis fund – published the eight-volume of British Entomologya a. together with the founding of entyomological DISADVANTAGES OF societies in Paris and London, makes entomology to emerge as a distinct field of ARTHROPODS study in the early 19th century Entomophobia – fear of insects that may cause nervous Entomology in Philippines disorder, hysterics, hallucinations Accidental Injury to sense organs by entering eyes, Johann Friedrich Eschsholtz ears, mouth, or nostrils – (physician and naturalist on the Russian ship Rurik) first entomologist investigator in the Philippines which Allergic/Asthmatic reactions by their odor, secretions, he visited in 1816 and dead fragments D.Molf  2 Envenomization – release of venom by insect via bite or sting that may cause swelling, pain, redness, rash, fever, FUNCTIONS OF BODY WALL allergic reactions, blood poisoning, or death It provides the structure, size, and shape of the insect Parasitism – symbiotic relationship where the body. arthropod (louse, ticks) harms the host It provides water resistance/balance for the insect. – mylasis or infestation by larva of Diptera on man and It protects the insect organs against physical harm. animals It provides the space for muscle attachment. It helps to prevent the entry of harmful microbes and Pests –feeding or boring on domestic fabrics and chemicals. structures of buildings rendering it unusable or unsound It serves as an interface between insect and the – economic losses due to foliage and pod feeders environment. – nuisance It helps maintain an ionic balance in the insect body. Vector carrier of infectious organisms It serves as the site of sensory input. CUTICLE – outermost thick layer – secreted by epidermis Epicuticle – thin outermost layer varying from 1 to 4 μm – no chitin Cement Layer – secreted by dermal glands and is composed of lipoprotein ADVANTAGES OF – protects the body from external damage – gives the size and shape of the insect body ARTHROPODS Wax Layer – prominent layer that is 0.25 μm in Arthropods products such as honey, beeswax, and silk thickness – consist of long chain of hydrocarbons, esters of fatty Pollination of plants by pollinators such as butterfly and acids, and alcohols bees – waterproof because it prevents water loss from the body Pest control of predatory and parasitic insects Polyphenol/Outer Epicuticle Layer – non-static layer Source of protein, vitamins, and minerals by humans containing various types of phenols which are mainly and other animals used in the formation of proteins – resistant to acids and organic solvents INSECT BODY WALL Cuticulin/Inner Epicuticle Layer – amber-colored thin – external covering of the whole insect which is also layer over the surface of the epidermis that is called integument or exoskeleton strengthened by the outer polyphenol layer – ectodermal in origin – rigid, flexible, lighter, stronger, and variously modified in different body parts to suit insect adaptations Procuticle – differentiated after sclerotization process Exocuticle – darkly pigmented, hard, and sclerotized – offers rigidity to the cuticle and consists of mainly chitin, sclerotin, and a hard protein Endocuticle – soft, light-colored, and unsclerotized – contains more chitin but lacks sclerotin D.Molf  3 Spurs – occur on the legs of many insects and differ CUTICLE COMPONENTS from setae in by multicellular in origin Chitin – nitrogenous polysaccharide and accounds for 25-60% of the dry weight of the cuticle CUTICULAR PROCESSES – consists of high molecular weight polymer of anhydro- – have no membranous articulation N-acetyl glucosamine residues joined by β-glycosidic Mitotrichia/Fixed Hairs/Aculei – minute hair-like linkages. structure found on wings of Mecopteran and certain – embedded with proteins in the procuticle to form Diptera glycoproteins – insoluble in water, alcohol, organic solvents, and Spines – outgrowths of the cuticle which are more or dilute acids less thorn like in form Arthropodin – soft, water-soluble protein present in the endocuticle CUTICULAR INVAGINARTION – the conversion to sclerotin is known as sclerotization or tanning APODEME – hollow invagination to provide for muscle attachment Sclerotin – also known as tanned protein because of its amber coloration – only present in the exocuticle APOPHYSIS – solid invagination to provide mechanical support to Resilin – rubber-like elastic protein which is colorless various organs and present in the joints such as wing hinge ligaments, leg joints, clypeolabral joints or suture, and tergosternal joints MOLTING – shedding of inelastic exoskeleton from time to time to permit the increase in size and growth of insects EPIDERMIS/HYPODERMIS – unicellular layer formed from polygonal cells which modifies into cuboidal or columnar cells during the Apolysis process of molting – apo = formation ; lysis = dissolution – the cells are consists of well-developed nucleus and – dissolution of old cuticle other cytoplasmic contents – the adjacent cells are held together by cytoplasmic Ecdysis processes – ecdysial membrane starts splitting along the line of – all cells are glandular and secrete cuticles and weakness due to muscular activity of the inner enzymes involved in the production and digestion of old developing insect and also because of swallowing of air cuticles during molting & water resulting in the distention of the gut. The – cell differentiated into dermal glandsa, trichogen breaking at the ecdysial membrane is also due to the cellsb, molting glandsc, and peristigmatic glandsd pumping of blood from abdomen to thorax through a. producing cement layer muscular activity b. producing hair like seta or trichome – old cuticles break and the new instar comes out c. secreting molting fluid which digests the old starting from its ehad followed by the thorax, abdomen, cuticle and appendages d. around the spiracles in case of dipteran larvae Pharate Instar – the insect has both newly formed epicuticle and procuticle and old exocuticle and BASEMENT MEMBRANE epicuticle – basal part of the body wall formed from degenerated Exuviae – breakage of old cuticles epidermal cells and appear as non-living amorphous (shapeless) granular layer of integument – about 0.5 μm in thickness and consists of fibrous Sclerotization protein or glycosaminoglycans – turning dark or “tanning” of the freshly shed insect that has a soft, milky white colored new cuticle – process of hardening of the cuticle which involves the CUTICULAR OUTGROWTHS development of cross links between protein chains CUTICULAR APPENDAGES – involves differentiation of procuticle into outer hard exocuticle and inner soft endocuticle – outgrowths of the cuticle connected by means of a membranous joint – arise from modified epidermal cells HORMONES OF MOLTING Seta/Macrotrichia – commonly known as hairs and Juvenile Hormone (JH) – produced from corpora allata arise from a cup like alveolus or pit of brain that helps the insect to be in immature stage – hollow structures developed as extension of exocuticle and are produced by a single enlarged Molting Hormone (MH) – produced from prothoracic hypodermal cell called trichogen glands of the brain that induces the process of molting – connected to articular membrane D.Molf  4 Eclosion Hormone (EH) – released from neurosecretory Hypognathus [Hypo = below or under] cells in the brain that help in the process of ecdysis or – head is more or less vertical and the mouthparts are eclosion directed ventrally – considered by most insect morphologist to represent INSECT SEGMENTATION primitive or generalized condition – evident in most major groups of insects (grasshopper, – divided into three distinct regions known as Tagmata housefly, honeybee, cockroach) Opisthognathous [Opistho = behind] – retreating jaws – characterized by posteroventral postion of the mouthparts resulting from a deflection of the facial region – (bugs, leafhoppers, whiteflies, aphids) THORAX – region between the head and abdomen – segments are clearly visible – each segment is made up of three sclerites or plates namely Tergum or Notaa, Sternumb, and Pleuronc HEAD a. dorsal body plate – formed by the fusion of 6 segments b. ventral body plate – hard and highly sclerotized compact capsule bearing a c. lateral plate where legs arise group of feeding appendages around the mouth, sensory organs, and internally a major center of neuroendocrine coordination Procephalon – anterior part of the head – represents the preoral region of the head and bears tow paired structures (eyes and antennae) – Consists of the intercalary, antennary, and pre- antennary – thought to be derived from the ancestral head, the archencephalon or blastocephalon, after an Prothorax incorporation of at least one posterior trunk segment of – segment closest to the head the ancestor – bears the first pair of legs and pronotum Procephalon Mesothorax – posterior part of the head – middle segment – mostly developed in order to equip the head with – bears the second pair of legs and anterior wing feeding with appendages – consists of mandibulary, maxillary, and labial Metathorax – posterior segment, near the abdomen SEGMENTS OF INSECT HEAD – bears the third pair of legs and posterior wings Preantennary segment Antennary segment ABDOMEN Intercalary segment – consists of 6-10 segments while the unusual number Mandibular segment ranges from 9-12 Maxillary segment – bears the heart and reproductive organs such as Labial segment ovaries and testis – basic number of segments is eleven plus the telsona a. bears the anus TYPES OF HEAD ORIENTATION – posterior-most/final division of the body of insect or arthropods – sometimes, additional division that is not a true segment on account of not arising in the embryo from teloblastic areas as other segments –never carry any appendage Prognathous [Pro = Front ; Gnathous = Jaw] Caudal furca – divided tail located in telson – head remains in the same axis to the body and mouthparts are projected forward – common in insects that burrow and predatory (beetles, earwigs, stoneflies) D.Molf  5 Clavate antenna (carion beetles) – gradually clubbed at INSECT APPENDAGES the end ANTENNAE/FEELERS *Stylate antenna (robber flies, snipe flies) – pointed horn like – paired and located on the front portion of the head – principal sense organs of insect – segmented LEGS – vary in form and structure – three pairs with each pair – could aid in the increased sensory activities such as – attached to thorax (pro, meso, metathorax) finding food and mate – each consists of five segments could aid in detecting sound vibrations, wind speed, or humidity Scape Coxa – proximal leg segment – basal segment that articulates with the head capsule – articulates with the cup like depression on the thoracic pleuron Pedicel –attached to the body – second antennal segment Trochanter Flagellum – second leg segment – all remaining “segments” or flagellomeres – usually small and single segmented – tow segmented in some species (dragonfly, damselfly) TYPES OF ANTENNAE Trochantellus – apparent second trochanter that is a part of femur Femur – third segment – largest segment – fixated to trochanter Filiform antenna (ground beetles) – thread like shape Tibia – long and provided with downward projecting spines Capitate antenna (Butterfly) – abruptly clubbed at the which aid in climbing and footing end – many are armed with large moveable spur near the apex Aristae antenna (house fly) – pouch like with a lateral bristle Tarsus *Lamellate antenna (scarab beetle) – folding fan like – further sub-divided into tarsomere – the basal segment is often larger than others and is Serrate antenna (click beetles) – saw toothed shape called basitarsus *Flabellate antenna (cedar beetle) – folding paper fan Pretarsus – terminal segment like – contain claws Moniliform antenna (termites) – bead like in shape – In diptera, consists of membranous pulvili Setaceous antenna (dragonfly, cockroach) – simplest type having bristle shape TYPES OF LEGS Geniculate antenna (bees, ants) – hinged or bent like an elbow Plumose antenna (moth, mosquito) – have horizontal brushes on root antenna Pectinate antenna (glow worm, fire colored beetles) – comb like shape D.Molf  6 Ambulatorial (mantids, leaf beetle, bug) – walking leg TYPES OF WING INCLUSIONS Cursorial (cockroaches, ground beetle, tiger beetle) – running leg Hair (caddisflies) – cilia structures on the wings Saltatorial (grasshopper, flea) [saltate = to jump or Scales (moths, butterflies) – unicellular scales covering vault] – for jumping the wings Raptorial (wasps, mantis) – front pair of legs is often *Hamuli (bees) –hook-like setae that connects the modified to grasp and hold pray for feeding forewings and hindwings Sticking legs (housefly) – hold onto ground using Frenulum (butterflies) – a bristle or row of bristles on adhesive pads under claw called pulvilli the edge of the hind wing that keeps it in contact with the forewing Natatorial (diving beetles) – swimming legs *Jugum (fruit sucking moth) – connecting ridge or Clasping (front leg of male predaceous diving beetle) projection of the wing – holding the female during copulation Some insects like dragonflies and damselflies Fossorial (mole cricket) – excavation or digging have two pairs (forewings, hindwings) of wings that may Stridulating (cricket, grasshopper) – sound production work separately. But in higher pterygote insects, fore and hind wings are coupled together as a unit, so that Scansorial (head lice) – holding an object, clinging or both pairs move synchronously. climbing Wing Coupling – four wings of insect becomes Foragial legs (honey bees) – collect food materials such functionally two winged as carrying pollen Basket-like leg (dragonfly, damselfly) – spiny and TYPES OF WING COUPLING closely placed use for seizing the prey and storing their prey Hamulate (bees) – a row of small hooks is present on the coastal margin of the hind wing which is known as Crawling (caterpillar) – abdominal legs, fake legs hamuli. These engage the folded posterior edge of forewing. WINGS Amplexiform (butterflies) – linking structure is absent – extensions of the exoskeleton that develop in –simplest form of wing coupling adulthood for flight – coupling is achieved by broad overlapping of adjacent – located on second and third thoracic segments margins – enforced by several longitudinal veins Frenate (fruit sucking moth) Male: hindwing bears near the base of the TYPES OF WINGS coastal margin a stout bristle which is normally held by a curved process, retinaculum arising from the Elytra (beetles, earwigs) – hardened forewings for the subcostal vein found on the surface of the forewing protection of fragile hindwings Female: hindwing bears near the base of the – often colorful or adorned with pits and grooves, coastal margin a group of stout bristle which lies however, usually not used for flight beneath extended forewing and engages there in a retinaculum formed by a patch of hairs near cubitus Hemelytra (cicada, red cotton bug) – wings with thick and leathery base and membranous distal half Jugate (hepialid moths) – jugum of the forewings are lobe like and it is locked to the coastal margin of the Membranous (dragonfly, honeybee) – wings that are hindwings thin and transparent Tegmina (forewings of grasshoppers and cockroach) – leathery or parchment-like wings that serves a INSECT SENSE ORGANS protective function – used for host recognition and location – detect motion, vibrations, temperature, moisture, Halteres (hindwing of housefly) – modified wings into carbon dioxide and chemical substances small knobs Pseudo halteres (forewing of strepsiptera) – halteres located differently Fringed (thrips) – wing lamina is reduced in size, resembling feathers Fissured (plume moths) – wings with deep clefts or slits TYPES OF SENSE ORGANS D.Molf  7 Sight Organs Sensillum – simple sensory organ or receptor Compound Eyes – visible externally on the body or appendages of – made up of multiple ommatidia arthropods like in fleas – can’t be focused or moved – modified as a sensory organ and is located on the – larger and more visible dorsal regions of the terminal abdominal segments – number of ommatidia influence the how detailed the – specialized for detecting host-associated cues like image vibrations and temperature changes Trichobothria – mechanoreceptor for tactile stimuli – specialized sensory setae of arthropods distinguished by a cuticular depression or socket at the base – common in mites and other arachnids for detecting airborne and substrate vibrations as well as other tactile cues Heller’s Organ – commonly found in ticks Facets/Cornea/Lens – curved hexagonal tube-like lens – complex sensory structure located on the dorsal on the external surface of each ommatidium aspect of the tarsus of the first pair of legs and functions in detection of temperature, air movements, Crystalline Cone – beneath the cornea host odors, taste, mechanical stimuli, and other host – helps focus the light onto the photoreceptor environmental cues Rhabdom – light-sensitive receptive structure formed by the inner margins of the retinula cells Antennae/Feelers – primary site of olfactory organs which is thousands – rod-like and made up of interdigitating fingerlike – have receptors that detect chemicals (blood-feeding processes called microvilli that are contributed by a insects particularly hematophagous dipterans) small number of retinula cells – used for finding mates, locating food, avoiding Membrane Fenestrate – thin membrane that separates predators, and gathering in groups cones and rods from the optic tract Some insect rely on chemical cues to find their way to Optic nerves – transmits the sight to the brain and from a nest, or to space themselves appropriately in a habitat limited resources Retinula Cells/Photoreceptors – detect light and convert it to electrical signals Johnson’s organ – organ specialized for detecting airborne vibrations possess by mosquitos Pigment Cells – different kinds (yellow-green, blue, ultraviolet) that separate ommatidium from the next – restrict the amount of light that each rhabdom Maxillary palps – specialized mouthpart receives – typically one pair of segmented, sensory appendage on the maxilla of insects Ocelli/Simple Eyes – function to feel, taste, and manipulate food – differ from compound eyes by having only one facet – collect and focus light via single lens – appear as small swellings Setae/Taste Bristles – slender hairlike cuticular projection of an epidermal – two or three cell of the arthropod integument – useful for detecting changes in light rather than – contain four chemoreceptor cells with dendrites that differentiating visual images extend to the pore at the tip of the sensory hair All adult insects with compound eyes have ocelli, which are usually found on their back or face. Some species of Tympana dragonfly and mayfly have nymps or naiads that have – consists of a membrane tightly stretched on a frame ocelli over an air-filled cavity – vibrate sound waves in the air is catch Stemmata/Lateral Ocelli – detect sound pressure via the movement of a – found in larvae forms of insects that undergo comple tympanal membrane which is equivalent to eardrum metamorphosis (beetles, wasps, butterflies, flies, fleas) that becomes deformed by fluctuations in the far-field – single ommatidia located on the sides of the larva’s pressure component of sound. head – can recognize light changes, color, distance, and form Other Sense Organs D.Molf  8 METAMORPHOSIS Semilooper – bears 3 pairs of thoracic legs and 3 pairs of prolegs – change in the body form and habits during the – Prolegs are present on 5th, 6th, and 10th abdominal development cycle of animals segments – example is castor semilooper, cotton semilooper TYPES OF METAMORPHOSIS Looper Ametabolous/Gradual Metamorphosis (grasshopper) – bears 3 pairs of thoracic legs and 2 pairs of prolegs – undergo little or no metamorphosis – Prolegs are present on 6th and 10th abdominal segments Hemimetabolous/Incomplete Metamorphosis (cicada) – example is cabbage looper – involves three life stages (egg, larva or nymph, adult) Holometabolous/Complete Metamorphosis (butterfly) Apodous – most strikingly different larva and adult stages – without appendages for locomotion – includes pupa Eucephalous LARVAE – has well-developed head capsule with functional – stage in the development of many animals that occurs mandibles, maxillae, stemmata, and antennae after birth or hatching and before the adult form – mandibles act transversely – juvenile stage of insects – example is wriggler and grub of red palm weevil – immature stage between egg and pupal stage of insects with complete metamorphosis – has a different appearance to the adult and may Hemicephalous possess bodily organs that the adult insect does not – reduced head capsule and its appendages possess – the head can be withdrawn into the thorax – wingless and often wormlike feeding form that – mandibles act vertically hatches from the egg of many insects – example is honey bees, robber flies, and horse flies TYPES OF LARVAE Acephalous – no obvious head capsule and cephalic appendages Oligopod – mouthparts consist of a pair of prostrusible curved mouth hooks and associated internal sclerites – well segmented body – example is maggot – well developed cephalic appendages and 3 thoracic legs – abdominal appendage are absent PUPAE – life stage of insects with complete metamorphosis Campodeiform which occurs between larval and adult stages – resemblance to the dipluran genus Campodea – nonfeeding stage – have elongated more or less fusiform like tapering at – typically undergoes complete transformation within a both the ends protective cocoon or hardened case – body is elongate, depressed dorsoventrally and well sclerotized TYPES OF PUPAE – head is prognathous – thoracic legs are long Obtect – a pair of abdominal cerci or caudal processes is usually – various appendages such as viz, antennae, legs, and present wing pads are glued to the body by a secretion – generally predators and are very active produced during the last larval molt – example is grub of antlion or grub of ladybird beetle – exposed surfaces of the appendages are more heavily sclerotized than those adjacent to the body Scarabaeiform – body is “C” shaped, stout and subcylindrical Chrysalis – head is well developed – naked obtect pupa of butterfly – thoracic legs are short – angular and attractively colored – caudal processes are absent – attached to the substratum by hooks present at the – sluggish, burrowing into wood or soil terminal end of the abdomen called cremaster – example is grub of rhinoceros beetle – the middle part is attached to the substratum by two strong silken threads called gridle Polypod/Eruciform – body consists of an elongate trunk with a large Tumbler sclerotized head capsule – comma shaped with rudimentary appendages – head bears a pair of powerful mandible which tear up – breathing trumpets are present in the cephalic end vegetation – anal paddles are present at the end of the abdomen – well segmented body – abdomen is capable of jerky movements which are – possesses three pairs of thoracic legs and 2 to 5 pairs produced by the anal paddles like in pupa of mosquito of abdominal prolegs D.Molf  9 Exarate POST-DIAPAUSE QUIESCENCE – various appendages such as viz, antennae, legs, and – after the termination wing pads are not glued to the body – continuation of the insects development provided – encompasses all oligopod larvae that environmental conditions improved – soft and pale Coarctate – barrel shaped, smooth with no apparent appendages – last larval skin is changed into case containing the exarate pupa – hardened dark brown case is called puparium – an example is fly pupa DIAPAUSE – delay in development caused by recurrent, regular periods of unfavorable environmental conditions in animals’ dormancy – physiological state has extremely particular beginning and inhibitory circumstances – the mechanism is a way to endure foreseeable undesirable environmental conditions like temperature extremes, droughts, or lack of food – exhibited by all life phases of arthropods particularly insect – sensitive stages occur at the embryonic, larval, pupal, or adult stage – stimulus must occur for an organism to proceed – triggered by certain environmental stimuli known as “token stimulia” a. no negative impact on any of the factors but indicate an impending change in the environmental conditions TYPES OF DIAPAUSE Obligatory Diapause Facultative Diapause INDUCTION – occurs long before unfavorable environmental conditions arise PREPARATION – comes after induction – insects store substances including carbohydrates, proteins, and lipids to keep themselves alive throughout the diapause INITIATION – one of the most significant periods – defined by cessation of morphological development MAINTENANCE – distinguished by reduced metabolism and an arrest in embryological development TERMINATION – end of diapause Certain insects rely on specific environmental cues to trigger the termination of diapause D.Molf