Lec. 15 Types of larvae and Pupa.ppt
- 1. 1 R.K. Panse Asstt. Prof. (Entomology) Lecture no. 15 TYPES OF LARVAE AND PUPAE
- 2. 2 Larvae Larval stage is the active growing stage. It is the immature stage between the egg and pupal stage of an insect having complete metamorphosis. This stage differs radically from the adult. Characteristics: Mouth parts and feeding habits differ Visual organs – lateral oceli or stemmata Wings pad Juvenile hormones
- 3. 3 There are three types of insect larvae : Apodous Oligopod Polypod Protopod TYPES OF LARVAE APODOUS: They are larvae without appendages for locomotion. Based on the degree of development and sclerotization of head capsule there are three subtypes. a. Eucepalous : Larva with well developed head capsule with functional mandibles, maxillae, stemmata and antennae. e.g. Wriggler (larva of mosquito).
- 4. 4 b. Hemicephalous : Head capsule is reduced and can be withdrawn into thorax. e.g. Larva of horse fly. c. Acephalous : Head capsule is absent. They are also called vermiform larvae. e.g. Maggot (larva of house fly).
- 5. 5 Oligopod : Thoracic legs are well developed. Abdominal legs are absent. Well developed head capsule. There are two subtypes. a. Campodeiform : They are so called from their resemblance to the dipluran genus Campodea. Body is elongate, depressed dorsoventrally and well sclerotised. Thoracic legs are long. Larvae are generally predators and are very active. e.g. grub of antlion and lady bird beetle.
- 6. 6 b. Scarabaeiform : Body is `C' shaped, stout and subcylindrical. Head is well developed. Thoracic legs are short. Larva is sluggish, burrowing into wood or soil. e.g. grub of rhinoceros beetle.
- 7. 7 2. POLYPOD or ERUCIFORM : The body consists of an elongate trunk with large sclerotised head capsule. Three pairs of thoracic legs and upto five pairs of unjointed abdominal legs or prolegs are present. Thoracic legs are segmented and they end in claws which are used for holding on to the leaf. Bottom of the proleg is called planta which typically bears rows or circlet of short hooked spines or crochets which are useful in climbing to the exposed surface of vegetation and walking. Abdominal segments three to sixand ten typically bear prolegs. e.g. Caterpillar.
- 8. 8 Protopod larvae: Emerge in early embryonic phase Lie in highly nutritive medium Devoid segmentation in abdomen Rudimentary cephalic and thoracic appendages Undeveloped respiratory and nervous system e.g. maggot of fruit fly
- 9. 9 a. Hairy caterpillar : The body hairs may be dense, sparse or arranged in tufts. Hairs may cause irritation, when touched. e.g. Red hairy caterpillar. b. Slug caterpillar : Larva is thick, short, stout and fleshy. Thoracic legs are minute. Such larva is also called platyform larva. e.g. Castor slug caterpillar
- 10. 10 c. Semilooper : Either three or four pairs of prolegs are present. e.g. castor semilooper. d. Looper : In this type, only two pairs of prolegs are present in sixth and tenth abdominal segments. e.g. Daincha looper.
- 11. 11 PUPA It is the resting and inactive stage in all holometabolous insects. During this stage, the insect is incapable of feeding. During the transitional stage, the larval characters are destroyed and new adult characters are created. There are three main types of pupae. OBTECT : Various appendages of the pupa viz., antennae, legs and wing pads are glued to the body by a secretion produced during the last larval moult. e.g. moth pupa. a. Chrysalis : It is the naked obtect pupa of butterfly. It is angular and attractively coloured.
- 12. 12 b. Tumbler : Pupa of mosquito is called tumbler. It is an obtect type of pupa. It is comma shaped. The pupa is very active. EXARATE : Various appendages i.e. antennae, legs, wing are not glued to the body. They are free. All oligopod larvae will turn into exarate pupae. e.g. Pupa of rhinoceros beetle. COARCTATE : The pupal case is barrel shaped, smooth with no apparent appendages. The last larval skin is changed into case containing the exarate pupa. The hardened dark brown pupal case is called puparium. e.g. Fly pupa.