• E T Haridass

      Articles written in Proceedings – Animal Sciences

    • Models for the predatory behaviour of some reduviids from Southern India (Insecta—Heteroptera—Reduviidae)

      E T Haridass T N Ananthakrishnan

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      The predatory behaviour of three reduviids, the millipede-feedingHaematorrhophus nigroviolaceus (Reuter) (Ectrichodiinae), the insectivorousPirates affinis Serville (Piratinae) and the haematophagousTriatoma rubrofasciata (De Geer) (Triatominae), both under natural and laboratory conditions, is discussed. Visual stimuli elicited by the moving prey appear important for the initiation of feeding response. The olfactory stimuli from the defensive secretions of the prey appear to enhance the response and help in the continuation of feeding. In the haematophagousTriatoma rubrofasciata, while feeding responses are elicited only by the temperature gradient around their vertebrate hosts, the visual and olfactory senses play only a minor role. On the basis of observations on feeding behaviour, appropriate predatory behaviour models for the three reduviid species have been constructed.

    • Functional morphology of the fossula spongiosa in some reduviids (Insecta—Heteroptera—Reduviidae)

      E T Haridass T N Ananthakrishnan

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      Legs of Reduviidae show modifications and specialised structures adapted for their predatory habits and efficient prey capture. The variable forelegs of these insects apparently reflect the correlation between the structure of the legs and the types of prey. The tibial pads or fossula spongiosa are a common feature in the forelegs or fore- and midlegs of most of subfamilies of Reduviidae. The functional morphology of the tibial pads of the forelegs of three insects,Haematorrhophus nigroviolaceus (Reuter),Pirates affinis Serville andTriatoma rubrofasciata (De Geer) has been studied. The oily substance produced by the cushion-like secretory tissue and the minute tenet hairs on them increase the ability to sustain static tension and enhance the gripping efficiency of the legs. Scanning electron micrographs reveal distinct morphological variations among the tibial pads. In addition to the shape and size of the organs, the number, structure and density of the tenet hairs on them markedly vary. The ability of the foretibial pad to sustain static tension on smooth and rough surfaces has been found to differ among the insects studied and this is remarkable in predatory insects.

    • Functional morphology of pylorus and rectal glands in Reduviidae (Insecta—Heteroptera)

      E T Haridass T N Ananthakrishnan

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      Anatomical and histological studies of the alimentary organs of sixteen reduviids, with diverse food habits indicate structural variations. The terminal part of the tubular second midgut of these predaceous insects has a permanent sac-like region with distinct histology, concerned with absorption of digested food. In addition, the digestive system is characterised by a reduced pylorus with pyloric-intestinal and pyloric-rectal valves, surrounded by flask-shaped ampullae of the four malpighian tubules. The ampullary cells with their filamentous apices and with fibrillar cytoplasmic processes are concerned with. water absorption. Commonly in all these terrestrial insects, the anterior end of the rectum also bears a well-developed, inverted cup-like rectal gland, the cells of which also absorb water from the excreta stored in the impermeable, intima lined rectum. Members of Ectrichodiinae show simple ampullary cells and a unique rectum, reported for the first time among reduviids with scattered dome-shaped glandular cells as found in Homoptera and in some phytophagous Heteroptera. The simple nature of the alimentary organs indicates its primitive organization within the reduviid subfamilies.

    • Feeding and ovipositional behaviour in some reduviids (Insecta-Heteroptera)

      E T Haridass

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      Feeding behavioural studies of many exclusively predatory species exhibit clearcut stimuli-response mediated sequences and these can be categorised into distinct sub-units like: search and location of prey → approach and attack of prey → immobilisation of prey → transportation of prey to safe place → consumption of prey. These feeding behavioural activities differ among reduviids particularly with respect to prey types. These bugs are endowed with many structural, physiological and behavioural adaptations for efficient predation.

      The ovipositional behaviour of reduviids in different habitats also shows considerable variation and their reproductive strategies include selection of suitable sites to assure successful emergence and development of young ones and so far very few egg predators and egg parasites have been reported for these terrestrial insects.

    • Ultrastructure of the eggs of Reduviidae: I. Eggs of Piratinae (Insecta—Heteroptera)

      E T Haridass

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      Eggs of Piratinae are unique among reduviids in possessing stellate chorionic filaments that remain exposed even after the insertion of the egg into the ground. These eggs have developed many structures for supplying ambient oxygen to the developing embryo inside them. The ultrastructure of the chorion, the operculum and the aeromicropylar system of the eggs of seven species of piratinae bugs are reported.

    • Ultrastructure of the eggs of Reduviidae: II eggs of Harpactorinae (Insecta: Heteroptera)

      E T Haridass

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      The harpactorine eggs, laid in clusters and covered by spumaline secretions, are distinguished from the eggs of other reduviid subfamilies by the elaborate net-work-like chorionic collar extensions and opercular outgrowths. The collar extensions may be short with spongy structure, or considerably long with honeycomb structure terminating in filamentous apices. The body of the egg has prominent follicular markings and the anterior end is marked by a distinct collar having the spermatic groove, aero-micropylar openings and the sealing bar. The chorionic collar extensions and the opercular outgrowths, along with the aero-micropylar systems and the inner aerostatic layer, efficiently transport atmospheric oxygen to the interior of the eggs. The ultrastructure of the chorion, the operculum and the aero-micropylar system of 5 species of harpactorine bugs from Southern India is reported.

    • Ultrastructure of the eggs of Reduviidae: III. Eggs of Triatominae and Echtrichodiinae (Insecta-Heteroptera)

      E T Haridass

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      Eggs of Triatominae and Echtrichodiinae, though identical, present distinct ultrastructural diversities in respect of collar rim, follicular pattern, position and distribution of the aero-micropylar system and the operculum, facilitating easy identification of the eggs of the species of the subfamilies. Possessing as they do, a continuous endochorionic aerostatic layer for supplying ambient oxygen to the developing embryos, they simulate other reduviid eggs. While the eggs of Triatominae are comparatively simple, being laid in exposed habitats, those of Echtrichodiinae possess additional opercular respiratory structures in view of their oviposition in specialised habitats.

    • Feeding and behavioural parameters and egg ultrastructure in the biosystematics of Reduviidae (Insecta—Heteroptera)

      E T Haridass A Balu M Noble Morrison

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      The feeding behaviour exhibited by the different subfamilies of Reduviidae is distinctly correlated with the specific prey types involved. Important adaptive modifications are seen associated with their methods of prey capture and feeding. Based on the analyses of feeding behaviour, reduviids may be grouped as (i) ‘blood feeding’ type, (ii) ‘sticky-trap’ type, (iii) ‘raptorial’ type, (iv) ‘wait and grab’ type, (v) ‘pin and jab’ type and (vi) ‘chase and pounce’ type. The oviposition methods are highly varied in Reduviidae and it is possible to assign group characteristics, but the ultrastructure of the eggs, particularly those of chorionic collar extensions and the operculum, indicate subfamily resemblance. The usefulness of feeding and reproductive behaviours and the egg ultrastructure in the biosystematics of Reduviidae are discussed.

    • Predatory behaviour ofRhinocoris marginatus Fabricius (Harpactorinae—Reduviidae—Heteroptera—Insecta)

      E T Haridass M Noble Morrison A Balu

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      The pin and jab type of predatory behaviour ofRhinocoris marginatus Fabricius is distinctly different from the feeding behaviour of other subfamilies known so far. The thin long legs, tibial pads, long slender rostrum capable of more than 90° forward extension, slow gait of this predator are idenlly suited for efficient capture of soft-bodied prey types, particularly caterpillars. As in other predatory reduviids, visual stimuli provided by the moving prey, elicit feeding responses inRhinocoris marginatus and this is augumented by other sensory system, including olfactory. The predatory feeding behaviour ofRhinocoris marginatus consists of disinct stimuli—response mediated sequences of events and based on these the feeding behaviour models for this insect is depicted.

    • Ultrastructure of the eggs of reduviidae: IV. Eggs of Rhaphidosomatinae (Insecta—Heteroptera)

      E T Haridass

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      Eggs of Rhaphidosomatinae share with the eggs of other subfamilies, several characters common to Reduviidae. The chorion with simple follicle cells, short, highly porous collar rim, 6 micropyles and the operculum with a central highly porous conical disc are characters to distinguish the eggs of this from other reduviid subfamilies. The ultrastructural details of the chorion, the operculum, and the aero-micropylar system of the eggs ofRhaphidosoma atkinsoni, the only species represented in India, are reported.

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