Michael Siva-Jothy

Last updated
Michael Siva Jothy
Alma mater University College London (BSc) University of Oxford (PhD)
Scientific career
Institutions Nagoya University, University College London, University of Sheffield

Michael 'Mike' Siva-Jothy is an entomologist in the UK, he is Professor of Entomology at the University of Sheffield. [1]

Contents

Education and career

Siva-Jothy was educated at University College London graduating with a BSc in 1981, he then did a PhD at the University of Oxford graduating in 1985. [1] He moved to Nagoya University in Japan as a Royal Society & Japan Society for the Promotion of Science Fellow until 1989, when he moved back to the UK to work as an Agricultural and Food Research Council research associate at University College London. [1] In 1990 Siva-Jothy moved to the University of Sheffield to be a lecturer, where he has remained, progressing to Senior Lecturer and Reader, Professor in 2006 and was the Head of the Department of Plant and Amimal Sciences from 2012 to 2018. [1]

Research

Siva-Jothy's research looks at the sexual and life history traits of arthropods. [1]

He worked on the mechanism of sperm competition in libellulid dragonflies for his PhD where he showed that Ecological drivers such as operational sex ratio selected for sperm competition mechanisms that were thorough (but took a long time) or were swift but did not result in long-lasting sperm precedence.

Siva-Jothy's early work in Japan developed this theme in an endemic damselfly, Mnais pruinosa, where Siva-Jothy showed that males could adopt different sperm-competition strategies depending on the likelihood that females would lay eggs immediately after mating or not [2]

Later, he looked at insect mating preferences in damselflies and found, using infra red cameras, that females prefer males with a higher body temperatures, which could then lead to eggs being laid in more favourable warmer habitats. [3]

He has extensively worked on bed bugs and found that female bed bugs prepare themselves for mating, protecting themselves from sexually transmitted infections by producing lysozyme, a bacteria killing enzyme [4] and by boosting their immune system. [5] His team have also found that bed bugs will feed on human blood for 10 to 20 minutes, increasing their body weight by up to 200 percent. [6] With an international team he discovered that bed bug species have been around for at least 115 million years and survived the extinction of the dinosaurs. [7]

With an experiment on insects and humans Siva-Jothy found that the hairs on human bodies can enable us to feel parasites on us and slow down their movement so that they take longer to find a feeding site. [8]

Honours and awards

Siva-Jothy's image of a Scarce swallowtail butterfly and a Polistine wasp on a Scabius flower won first place in the Community, Population and Macroecology category of the 2013 BioMed Central's Ecology Image Competition. [9]

Related Research Articles

<i>Drosophila</i> Genus of flies

Drosophila is a genus of flies, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit. They should not be confused with the Tephritidae, a related family, which are also called fruit flies ; tephritids feed primarily on unripe or ripe fruit, with many species being regarded as destructive agricultural pests, especially the Mediterranean fruit fly.

<span class="mw-page-title-main">Dragonfly</span> Predatory winged insects

A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of true dragonflies are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threatens dragonfly populations around the world. Adult dragonflies are characterized by a pair of large, multifaceted, compound eyes, two pairs of strong, transparent wings, sometimes with coloured patches, and an elongated body. Many dragonflies have brilliant iridescent or metallic colours produced by structural colouration, making them conspicuous in flight. An adult dragonfly's compound eyes have nearly 24,000 ommatidia each.

<span class="mw-page-title-main">Damselfly</span> Suborder of insects

Damselflies are flying insects of the suborder Zygoptera in the order Odonata. They are similar to dragonflies but are smaller and have slimmer bodies. Most species fold the wings along the body when at rest, unlike dragonflies which hold the wings flat and away from the body. An ancient group, damselflies have existed since at least the Lower Permian beginning about 299 million years ago, and are found on every continent except Antarctica.

<span class="mw-page-title-main">Behavioral ecology</span> Study of the evolutionary basis for animal behavior due to ecological pressures

Behavioral ecology, also spelled behavioural ecology, is the study of the evolutionary basis for animal behavior due to ecological pressures. Behavioral ecology emerged from ethology after Niko Tinbergen outlined four questions to address when studying animal behaviors: What are the proximate causes, ontogeny, survival value, and phylogeny of a behavior?

<span class="mw-page-title-main">Sperm competition</span> Reproductive process

Sperm competition is the competitive process between spermatozoa of two or more different males to fertilize the same egg during sexual reproduction. Competition can occur when females have multiple potential mating partners. Greater choice and variety of mates increases a female's chance to produce more viable offspring. However, multiple mates for a female means each individual male has decreased chances of producing offspring. Sperm competition is an evolutionary pressure on males, and has led to the development of adaptations to increase male's chance of reproductive success. Sperm competition results in a sexual conflict between males and females. Males have evolved several defensive tactics including: mate-guarding, mating plugs, and releasing toxic seminal substances to reduce female re-mating tendencies to cope with sperm competition. Offensive tactics of sperm competition involve direct interference by one male on the reproductive success of another male, for instance by physically removing another male's sperm prior to mating with a female. For an example, see Gryllus bimaculatus.

<span class="mw-page-title-main">Cimicidae</span> Family of parasitic blood-feeding insects

The Cimicidae are a family of small parasitic bugs that feed exclusively on the blood of warm-blooded animals. They are called cimicids or, loosely, bed bugs, though the latter term properly refers to the most famous member of the family, Cimex lectularius, the common bed bug and its tropical relation Cimex hemipterus. The family contains over 100 species. Cimicids appeared in the fossil record in the Cretaceous period. When bats evolved in the Eocene, they switched hosts and now feed mainly on bats or birds. Members of the group have colonised humans on three occasions.

<span class="mw-page-title-main">Indianmeal moth</span> Species of moth

The Indianmeal moth, also spelled Indian meal moth and Indian-meal moth, is a pyraloid moth of the family Pyralidae. Alternative common names are weevil moth, pantry moth, flour moth or grain moth. The almond moth and the raisin moth are commonly confused with the Indian-meal moth due to similar food sources and appearance. The species was named for feeding on Indian meal or cornmeal, and does not occur natively in India. It is also not to be confused with the Mediterranean flour moth, another common pest of stored grains.

<span class="mw-page-title-main">Calopterygidae</span> Family of damselflies

The Calopterygidae are a family of damselflies, in the suborder Zygoptera. They are commonly known as the broad-winged damselflies, demoiselles, or jewelwings. These rather large damselflies have wingspans of 50–80 mm, are often metallic-coloured, and can be differentiated from other damselflies by the broader connection between the wings and the body, as opposed to the abrupt narrowing seen in other damselfly families. The family contains some 150 species.

<span class="mw-page-title-main">Sexual conflict</span> Term in evolutionary biology

Sexual conflict or sexual antagonism occurs when the two sexes have conflicting optimal fitness strategies concerning reproduction, particularly over the mode and frequency of mating, potentially leading to an evolutionary arms race between males and females. In one example, males may benefit from multiple matings, while multiple matings may harm or endanger females, due to the anatomical differences of that species. Sexual conflict underlies the evolutionary distinction between male and female.

<i>Teleogryllus oceanicus</i> Species of cricket

Teleogryllus oceanicus, commonly known as the Australian, Pacific or oceanic field cricket, is a cricket found across Oceania and in coastal Australia from Carnarvon in Western Australia and Rockhampton in north-east Queensland

<span class="mw-page-title-main">Traumatic insemination</span> Mating practice in invertebrates

Traumatic insemination, also known as hypodermic insemination, is the mating practice in some species of invertebrates in which the male pierces the female's abdomen with his aedeagus and injects his sperm through the wound into her abdominal cavity (hemocoel). The sperm diffuses through the female's hemolymph, reaching the ovaries and resulting in fertilization.

<i>Megaloprepus caerulatus</i> Species of damselfly

Megaloprepus caerulatus, also known as the blue-winged helicopter, is a damselfly of the Forest Giant family within the Coenagrionidae family. Giant damselflies were previously recognized as their own family, Pseudostigmatidae. M. caerulatus is found in wet and moist forests in Central and South America. It has the greatest wingspan of any living damselfly or dragonfly, up to 19 centimeters (7.5 inches) in the largest males. Its large size and the markings on its wings make it a conspicuous species; a hovering Megaloprepus has been described as a "pulsating blue-and-white beacon". M. caerulatus is the only species in the genus Megaloprepus.

<i>Hetaerina</i> Genus of damselflies

Hetaerina is a genus of damselflies in the family Calopterygidae. They are commonly known as rubyspots because of the deep red wing bases of the males. The name is from Ancient Greek: ἑταίρα (hetaira), courtesan. H. rudis, the Guatemalan rubyspot, is considered vulnerable on the IUCN Red Data List.

<span class="mw-page-title-main">Harlequin cabbage bug</span> Species of true bug

The harlequin cabbage bug, also known as calico bug, fire bug or harlequin bug, is a black stinkbug of the family Pentatomidae, brilliantly marked with red, orange, yellow and white markings. It is a major pest of cabbage and related crops in the Brassicaceae, as well as the ornamental flower cleome throughout tropical and North America, especially the warmer parts of the United States. Nymphs are active during the summer and in the tropics the bug can achieve three to six generations a year. In the northern range there is only one generation annually and the insects overwinter as adults in crop residues or field edges. Organic control involves hand-picking the insects off the plants and being especially careful to remove and destroy all the eggs, which are black-and-white striped, laid in clutches of twelve.

<i>Cimex</i> Genus of true bugs

Cimex is a genus of insects in the family Cimicidae. Cimex species are ectoparasites that typically feed on the blood of birds and mammals. Two species, Cimex lectularius and Cimex hemipterus, are known as bed bugs and frequently feed on humans, although other species may parasitize humans opportunistically. Species that primarily parasitize bats are known as bat bugs.

Afrocimex constrictus, also called the African bat bug, is an insect parasite of Egyptian fruit bats in bat caves in East Africa. Population sizes can comprise millions of individuals and in a cave there can be one to 15 bugs per bat. It was estimated that adult African bat bugs feed approximately once per week thus withdrawing 1-28 microlitre blood per day per bat.

The spermalege is a special-purpose organ found in female bed bugs that appears to have evolved to mitigate the effects of traumatic insemination. The spermalege has two embryologically distinct parts, known as the ectospermalege and mesospermalege. The evolution of the spermalege as a female counter-adaptation for traumatic insemination was proposed by the French entomologist Jacques Carayon in 1966.

<span class="mw-page-title-main">Female sperm storage</span>

Female sperm storage is a biological process and often a type of sexual selection in which sperm cells transferred to a female during mating are temporarily retained within a specific part of the reproductive tract before the oocyte, or egg, is fertilized. This process takes place in some species of animals, but not in humans. The site of storage is variable among different animal taxa and ranges from structures that appear to function solely for sperm retention, such as insect spermatheca and bird sperm storage tubules, to more general regions of the reproductive tract enriched with receptors to which sperm associate before fertilization, such as the caudal portion of the cow oviduct containing sperm-associating annexins. Female sperm storage is an integral stage in the reproductive process for many animals with internal fertilization. It has several documented biological functions including:

Sexual antagonistic co-evolution is the relationship between males and females where sexual morphology changes over time to counteract the opposite's sex traits to achieve the maximum reproductive success. This has been compared to an arms race between sexes. In many cases, male mating behavior is detrimental to the female's fitness. For example, when insects reproduce by means of traumatic insemination, it is very disadvantageous to the female's health. During mating, males will try to inseminate as many females as possible, however, the more times a female's abdomen is punctured, the less likely she is to survive. Females that possess traits to avoid multiple matings will be more likely to survive, resulting in a change in morphology. In males, genitalia is relatively simple and more likely to vary among generations compared to female genitalia. This results in a new trait that females have to avoid in order to survive.

<i>Dryomyza anilis</i> Species of fly

Dryomyza anilis is a common fly from the family Dryomyzidae. The fly is found through various areas in the Northern hemisphere and has brown and orange coloration with distinctive large red eyes. The life span of the fly is not known, but laboratory-reared males can live 28–178 days. D. anilis has recently been placed back in the genus Dryomyza, of which it is the type species. Dryomyzidae were previously part of Sciomyzidae but are now considered a separate family with two subfamilies.

References

  1. 1 2 3 4 5 Sheffield, University of. "Professor Michael T Siva-Jothy - Academic Staff & Independent Research Fellows - People - Animal and Plant Sciences - The University of Sheffield". www.sheffield.ac.uk. Retrieved 2020-01-20.
  2. Siva-Jothy, Michael T.; Tsubaki, Yoshitaka (1989). "Variation in copulation duration in Mnais pruinosa pruinosa Selys (Odonata: Calopterygidae)". Behavioral Ecology and Sociobiology. 25 (4): 261–267. doi:10.1007/BF00300052. S2CID   24298339.
  3. Bourton, Jody (2010-05-18). "Female insects prefer hot males". BBC earth news. Retrieved 2020-01-20.
  4. Carpenter, Jennifer (2011-08-30). "Bed bugs protect sperm from germs" . Retrieved 2020-01-20.
  5. "Female bed bugs 'control' their immune systems ahead of mating to prevent against STIs". phys.org. 1 July 2019. Retrieved 2020-01-20.
  6. Zukerman, Joel Werner and Wendy (2015-08-04). "How bed bugs offer clues about the process of evolution". ABC Radio National. Retrieved 2020-01-20.
  7. Gill, Victoria (2019-05-16). "Bedbugs 'outlived the dinosaurs'". BBC News. Retrieved 2020-01-20.
  8. "The semi-naked ape, or why peach fuzz makes it harder for parasites". Discover Magazine. 13 Dec 2011. Retrieved 2020-01-20.
  9. Ferris, Robert. "Competition-Winning Pictures Of Life On Earth". Business Insider. Retrieved 2020-01-20.