Imitative strategies in insects: The mechanism of mimicry

Imitative strategies in insects: The mechanism of mimicry

• 1.
  Sher-e-Kashmir University of AgriculturalSciences and Technology of Kashmir Name of Student Saika Manzoor Registration No. 10/Ag(Entom)23-D Division Entomology Date of seminar 06/02/2024 Doctoral seminar
• 2.
  Imitative Strategies in Insects:The Mechanism of Mimicry
• 3.
  01 02 03 04 05 06 07 Introduction Batesian mimicry Mullerian mimicry CrypticColoration and Camouflage Evolution of mimicry Case studies Conclusion List of contents
• 4.
  Introduction • Mimicry ininsects is a fascinating evolutionary adaptation that involves one species (mimic) evolving to resemble another (model), often for protective purposes. • Insects have evolved several strategies in prey-predator interactions due to selective pressures, such as mimicry and camouflage Hanlon, 2007
• 5.
  • Both Mimicryand Camouflage enable insects to effectively reduce the probability of detection by prey and predators, insects have evolved such strategies through various pathways including utilizing specialized morphologies. • English naturalist Henry walter bates (1862) propounded the theory of mimicry. He defined mimicry as the resemblance in external appearance, shape and colour between members of widely distinct families.
• 6.
  Batesian Mimicry • Batesianmimicry occurs when a harmless or edible species evolves to imitate the appearance of a harmful or unpalatable species. • Mechanism: The mimicking species gains protection from predators by adopting the warning signals (such as coloration or patterns) of the model species. This reduces the likelihood of predation since predators learn to avoid the model species. Ruxton et al., 2018 Types of mimicry
• 7.
  Batesian mimicry, whereharmless species mimic harmful ones, is commonly observed in Wasp mimicry Bee mimicry Ant mimicry
• 8.
  An example ofBatesian mimicry, with hoverflies and wasps. Hoverflies are generally harmless; however, by mimicking the clear bright yellow warning systems of more dangerous species like wasps and bees, they avoid being eaten by predators such as birds. Carde, 2009.
• 9.
  Wasp mimicry • HoverFly • Eupeodes spp. • Diptera: Syrphidae • Mimicry: • Due to their similarities in color and relative shape hover flies are easily mistaken for wasps. Boppre et al., 2017
• 10.
  Why insects mimicbees? • Bees are widely recognized for their defensive capabilities, including stinging, and many predators have learned to avoid them. • By resembling bees, which are perceived as potentially harmful, these mimics reduce the likelihood of being attacked or consumed by predators • Unlike honeybees, bumblebees stingers are not barbed, so they can sting multiple times. Ant mimicry
• 11.
  Bees Mimicry • BeeFly • Bombylius spp. • Diptera: Bombyliidae • Mimicry: Their stout furry body and the buzzing noise made by their wings, make it easy to mistake them for Bumblebees. Kastinger and webber, 2018
• 12.
  • Bee Beetle •Trichius spp. • Coleoptera: Scarabaeidae • Mimicry: Bee Beetles avoid predation by mimicking the physical characteristics of the bumblebee. Bees Mimicry Wilson et al., 2018
• 13.
  • Drone fly(adult) • Rat-tailed maggot(immature) • Eristalis spp. • Diptera: Syrphida • Mimicry: Drone Flies avoid predation due to their physical similarities to honey bees and bumbles bees. Bees Mimicry Wilson et al., 2018
• 14.
  Why insects mimicants? • Ants have powerful defense mechanisms such as acid taste, aggressive biting, painful sting, and group defense thus, ants are generally not subject to predation. • Insects that mimic ants gain several advantages, including protection from predators and access to resources. Ant mimicry Hespenheide, 2014
• 15.
  Ants Mimicry • Myrmarachnespp • Myrmarachne is a genus of ant mimicking jumping spiders. • Salticidae • Mimicry: These spiders mimic the behavioral features of ants such as adapting their zig-zag locomotion pattern and the act of creating an antennal illusion by waving their first or second legs in the air. Wignall, 2010
• 16.
  Ants mimicry • Macroxiphussp. • Orthoptera: Tettigonidae • Cricket nymph mimics an ant to ward off predators • Mimicry: Their long antennae are camouflaged to appear short, being black only at the base and they are vibrated like ant antennae
• 17.
  Mullerian Mimicry • Mullerianmimicry is named after Fritz Muller, a German-Brazilian biologist. He independently proposed the concept of Mullerian mimicry in the late 19th century. • Mullerian mimicry is a type of mimicry where two or more harmful or unpalatable species evolve to resemble each other. • Mechanism: This form of mimicry is a mutualistic relationship where all the species benefit. Predators learn to avoid the shared warning signals, and all the mimetic species benefit from reduced predation. • Mullerian mimicry is common among stinging Hymenopterans (Bees, Wasps, and Ants). Sherratt, 2008.
• 18.
  Danaus plexippus LimenitisArchippus Schultz, 2018 Since both butterflies share the same pattern and both are toxic, it sends a strong signal to predators such as wasps to avoid them both. Predators associate the colors and patterns with aggressiveness and toxicity and are not likely to eat anything that exhibits these warning colors.
• 19.
  • Yellowjacket • Vespulaspp. • Hymenoptera: Vespidae • Mimicry: • A variety of harmless insects have evolved to mimic the coloration and markings of yellowjackets in order to avoid predation. • The yellow and black coloration and markings of yellowjackets serve as a warning to other organisms that they are potentially harmful. Mullerian Mimicry
• 20.
  • Both crypticcoloration and camouflage are remarkable examples of evolutionary adaptations that enhance an organism's chances of survival in their natural environment. • In insects, this includes the use of colors, patterns, and textures to blend in with their surroundings, to avoid predators by looking like part of their environment. Cryptic Coloration and Camouflage Fuente, 2012
• 21.
  Example of wingcolour patterns with a role in antipredator defences. (A) cryptic butterfly Steroma bega (Nymphalidae: Satyrinae) (B) Caligo butterfly (Nymphalidae: Brassolinae) that harbour conspicuous eyespot that have a deimatic or deflective function to predators (C) conspicuous coloured butterfly (Nymphalidae: Heliconiinae), here the wing pattern signals unpalatability to predators(D) Arawacus butterfly (Lycaenidae) harbours a false head with movement deflects predators’ attacks.
• 22.
  Microcentrum spp. Orthoptera: Tettigoniidae Typeof Mimicry: Cryptic Coloration/Camouflage (Homotypism) • Their wings have venation patterns that look similar to those of leaves. • Some species even have spots on theirs wings that look like they have been eaten by herbivorous insect or spot that look like moss or lichen growing. While some species look like dead or dying leaves. Katydid
• 23.
  Orchid Mantis Hymenopus coronatus Dictyoptera:Hymenopididae • Mimicry: (Homochromism) • Flower mantids blend in with their surroundings. This protects them from predators, and also disguises them from passing prey.
• 24.
  Hemeroplanes triptolemus Lepidoptera: Sphingidae •In it’s larval stage, this Sphinx Moth caterpillar can make itself look like small snake when it feels threatened by puffing up the area around its head. It has two spots on the ventral side of its head that resemble snake eyes when they are expanded. It will even mimic snake behavior by striking at predators. • Mimicry: Cryptic coloration/Camouflage (Homomorphism) Sphinx Moth (Snake mimic caterpillar)
• 25.
  Evolution of mimicry •Mimicry in insects has evolved over time as a result of selective pressures from interactions with other organisms, such as predators, prey and competitors. • Batesian mimicry emerges when a harmless species evolves to imitate the appearance of a harmful or unpalatable model, exploiting the learned avoidance behaviors of predators. This mimicry provides a survival advantage by reducing the likelihood of predation. • Mullerian mimicry, on the other hand, involves multiple harmful species evolving to share similar warning signals, reinforcing avoidance learning among predators. Turner, 1987
• 26.
  • Predator Learning Mimicryevolves as a response to the learning abilities of predators. Mimics gain an advantage by exploiting the predator's ability to associate certain visual or chemical cues with danger. • Selective Pressures Natural selection favors individuals that better mimic the harmful or unpalatable model. Over time, populations of mimics with more accurate mimicry traits are more likely to survive and reproduce. Factors influencing the evolution of mimicry in insects
• 27.
  • Gene Flow Geneflow within populations can contribute to the spread of mimicry traits. Individuals with successful mimicry traits are more likely to pass on their genes to the next generation. • Ecological Context The presence of specific predators, the availability of resources, and the overall ecological context influence the evolution of mimicry. Mimicry may be more prevalent in environments with a high abundance of predators or where certain prey species are more abundant.
• 28.
  Case Studies
• 29.
  • Researchers presentedblack-thorax and white-thorax flies to mantids over two weeks, altering the evasiveness of the flies by cutting wings based on color patterns. Each mantid had one training treatment, and there were 20 mantids per treatment. The study aimed to observe the influence on evasive behavior during predator interactions. Henry and Sherratt, 2023 Selection for evasive mimicry imposed by an arthropod predator
• 30.
  Figure 1. Showsthe frequency of outcomes (successfully capture white flies, black flies, or do not capture any fly) observed during the training phase. Training Phase • In the first treatment (BN/WC), white clipped flies were caught more than black unclipped flies. • In the second treatment (BC/WN), black clipped flies were caught more than white unclipped flies. • However, there was no significant difference in catch rates between clipped and unclipped flies of both colors in the third (BC/WC) and fourth (BN/WN) treatments
• 31.
  Test phase • Themantids were tested following the same sequential order of treatment as in the training phase. • The test phase was conducted once for each mantid Figure 2. The frequency of outcomes observed in the test phase.
• 32.
  • The resultssuggest that the training treatments influenced the mantids preferences and behaviors during the test phase, leading to variations in the likelihood of attacking black or white flies. • The findings from the test phase of the experiment indicate that mantids possess the ability to learn and adjust their predatory behavior based on their past experiences. • This study provides evidence for the concept of evasive mimicry and highlights the role of arthropod predators in the evolution of warning signals and mimicry. Results
• 33.
  Conducted a studyon jumping spiders (Evarcha arcuata) to examine their ability to learn and remember avoidance of different prey species. Raska et al., 2020 Adults of the firebug Pyrrhocoris apterus (A) and the red bug Scantius aegyptius (B), and nymphal instars of both species – the firebug (C) and the red bug (D).
• 34.
  Figure 1. Showsthe average attack rates and capture rates during five trials of the avoidance-learning test. The pink squares represent Pyrrhocoris apterus, the blue circles represent Scantius aegyptius and the white diamonds represent control fruit flies. The y-axis represents the rates of attack and capture, while the x-axis represents the trials. The dotted lines represent attack rates, and the full lines represent capture rates. • The attack and capture rates for both bugs decreases over time, indicating that the spiders learned to avoid attacking these prey species, and became less successful in capturing the prey. • In contrast, the attack rates and capture rates for the control fruit flies remain relatively stable throughout the trials, indicating that the spiders did not learn to avoid or have difficulty capturing the control prey.
• 35.
  The findings indicatethat the spiders rapidly learned to avoid both the true bug species, as evidenced by significant decreases in attack rates and capture rates over time. The stability in attack and capture rates in case of fruit flies suggests that spiders did not perceive fruit flies as dangerous prey. Pyrrhocoris apterus may be better defended against spiders compared to Scantius aegyptius, but the difference was only marginally significant. The results suggest that the mimetic relationship between the two species is most likely Mullerian, which means that both species benefit from their resemblance to each other. Results
• 36.
   In conclusion,mimicry in insects is a fascinating and diverse phenomenon that showcases the intricate mechanisms through which these organisms have adapted to their environments  Understanding the mechanisms of mimicry provides insights into the complex strategies employed by insects for self-preservation and reproduction.  As ongoing research continues to unravel new facets of mimicry, it enhances our comprehension of the intricate relationships that govern the survival and success of insects in diverse habitats. Conclusion
• 37.
  Nature has itsown way of playing hide and seek! Thank you