Caenocholax fenyesi
Caenocholax fenyesi | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Insecta |
Order: | Strepsiptera |
Family: | Myrmecolacidae |
Genus: | Caenocholax |
Species: | C. fenyesi
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Binomial name | |
Caenocholax fenyesi Pierce, 1909
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Caenocholax fenyesi is a species of twisted-winged parasitic insects in the order Strepsiptera and family Myrmecolacidae.[2] It has a sporadic distribution throughout North America, Central America, and South America.[3] Chaenochlax brasiliensis (Oliveira and Kogan 1959) is the only other named species in the genus.[2]
C. fenyesi displays heterotrophic heteronomy, where males and females occupy different hosts.
Taxonomy
Subspecies are cryptic and are morphologically similar, but genetically different.[6] These three subspecies belong to the species Caenocholax fenyesi:[6]
- Caenocholax fenyesi fenyesi Pierce, 1909
- Caenocholax fenyesi texensis Kathirithamby & Johnston, 2004
- Caenocholax fenyesi waloffi Kathirithamby & Johnston, 2004
Phylogeny and Genetic Structure
Phylogenetic relationships are inferred based on the morphology of adults and specific host associations.
Distribution
C. fenyesi is distributed throughout the southern United States, Central America, and South America.[3] Overall distribution in the United States includes Florida, New Orleans, southern and central Louisiana, Mississippi, Georgia, Arizona, Alabama, and Texas.[3] In the Neotropics, they are found in Cordoba, Mexico; Tabasco, Mexico; Peten, Guatemala; Metagalpa, Nicaragua; Costa Rica; Panama; Ecuador; Chile; Missiones, Argentina; Andros Island, Bahamas; and Cuba.[3] Individuals live in small numbers in close proximity due to the adult male's short lifespan.[4]
Habitat
Because males and females parasitize different insects, their respective habitats depend on host preferences and the intersection of the habitat and range of their different hosts.[4][3] Males, along with their ant hosts, are less common in grassland habitats.[3] There is not enough time for males to develop, establish, and occupy their own unique habitat.[3]
Local dispersal allows C. fenyesi to persist in a small area.[4] However, dispersal of larvae is extremely restricted because reproducing females must depend on a new orthopteran host for the larvae.[4] Males depend on a new ant host, which are difficult to find because ants usually stay close to their nest[3]. Poorly developed flight and short lifespans also constrain dispersal by males.[4] Overall, dispersal of male first instar larvae is extremely limited because adult and nymph stages of the ant host live within the same habitat.[6]
Reproduction and Development
Generalized Lifecycle
Females do not have a pupal instar stage.[5] Oocytes float freely in her haemolymph and she may produce up to 750,000 embryos.[5] Fertilization occurs by means of haemocoelic insemination and reproduction occurs by means of haemocoelous viviparity.[5] Motile first instar larvae are released through the brood canal opening in the female's cephalothorax.[4] When males find their ant host, the first instar larvae go through hypermetamorphosis, bore through the cuticle, and moult into the second instar larvae.[6][2]
Males moult several times and develop according to the following stages:[5]
- Prepupa: Prefrontal nervous system develops and complex eyes and wings develop further.
- Pupa: Wings and genitalia grow to full size.
- Subimago: Wings remain in their sheath.
- Imago: Cuticles from the prepupal, pupal, and subimaginal stages are shed; wings are fully inflated and flight muscles are developed; sperm matures.
Males emerge from the host when they reach adulthood and immediately begin to fly and search for a female to mate with.[6] Their adult lifespan is usually a few hours, but may be up to a few days.[3]
Copulation
Females send out sex hormones to attract a male[6]. The male strikes the female's cephalothorax with his tarsi during courtship to stimulate her[6]. Copulation may occur for up to a minute and multiple times before the male begins searching for another female to mate with[6].
Parasitism
Each host is occupied by one individual.
Anatomy
Males and females of C. fenyesi are sexually dimorphic.[2] There are four larval stages, but only three have been described.[5][2] Larval stages are named secondary and tertiary stages based on morphological characteristics, but are not necessarily sequential stages.[2] Endoparasitic larval stages experience apolysis, but no ecdysis.[2] First instar larvae are free-living, while secondary and tertiary larvae are endoparasitic in both males and females.[2] The sex of individuals can be determined by the time they reach the second instar stage.[5] By the third instar stage, males have three pairs of prolegs and a bulbous head; while females have a rounded "head" region and tapering abdomen.[5] The first four abdominal segments have sensory bristles in all larval stages.[2]
First Instar Larvae
The function of the first instar is to find a suitable host.[5] Physical environmental conditions affect the lifespan at this stage, so it is short-lived.[6] At this stage, individuals have a scleratized cuticle and are brown and 70-80 um long, not including the caudal filaments.[5][2] Ventral regions of the head, thorax, and abdomen are serrated, and dorsal and lateral surfaces are mainly smooth.[5][2] Legs are slender and spined, and tarsi have single joints, no claws, and ventral modifications to resemble adhesive pads.[5][2]
There are three pairs of pits on the dorsal surface of the head.
Each segment of the thorax has spiny sternal sclerites, a pair of dorsal pits, and a ventral-lateral pair of pits.[2] Some spines and serrations extend from the edge of the segment on the ventral side[1]. Tarsi on the legs of the prothorax and mesothorax have pads.[2] The metathorax has three finger-like projections anteriorly to each coxa.[2]
The abdomen has 10 segments with short, spiky projections on the lateral surface and serrations, spines, and two pairs of setal bristles on the ventral surface.[2] Segments 1-4 have a pair of ventral-lateral setaceous spines that are 4.5 um long[1]. Segments 4-7 each have a pair of 0.5-1.5 um-long spines on the ventral posterier edge.[2] Segments 7-10 have small, broad serrations on the posterior sternum ventrally.[2] There are two pairs of bristly lateral/dorsal setae 11 um long on segment 9 and one pair of 40. um-long caudal filaments on segment 10, which are used for jumping.[2]
Secondary Larvae
Individuals at this stage are 200-350 um in size and light brown, with a rounded head and membraneous cuticle.[2] There are 13 differentiated segments, but the last two segments are narrower than the others.[2]
Tertiary Larvae
This stage is similar to the secondary larva, but individuals are much larger at 600-700 um in size, and the head is less rounded and cap-like with a broadly pointed anterior end.[2]
Adult Female Anatomy
Females are wingless, eyeless, and possess no antennae, mouthparts, legs, or external genitalia.[8][7] They are relatively large in size at 1.5-3.9 mm.[10][8] Female first instar larvae are 0.89 mm long.[10] The female's head is vestigial and is fused to the reduced, indistinct segments of the thorax.[7] The mandibles have several spines on the inner surface.[10] The cephalothorax is 0.55 mm long and 0.43 mm wide, light brown, and lies flat on the host's abdomen and extrudes through the host's abdominal pleurites.[10] The brood canal opening is 0.18 mm long and 0.33 mm wide.[10] The second and third abdominal segments have a genital aperture.[10]
Adult Male Anatomy
Males range in size from 1.5 to 6 mm.
Biological Control in Red Imported Fire Ants (S. invicta)
C. fenyesi has been suggested as a potential agent for the biological control of the red imported fire ant, S. invicta in the United States and Australia[10]. When parasitized by C. fenyesi, red imported fire ants climb to a high perch and assume a gaster flagging posture and remain in this position until C. fenyesi emerges.[3]
S. invicta was introduced into the United States from South America in the early 1900s and have since expanded their range to cover more than 129.5 million hectares.[12] Chemical insecticides are commonly used for controlling their populations but because S. invicta has no natural enemies in North America, this is only a temporary solution and many biological control agents have been suggested.[12] However, this parasite of fire ants has a low rate of parasitization and currently more research is required to determine if C. fenyesi can be used as a reliable biocontrol of S. invicta.[12]
References
- ^ "Caenocholax fenyesi Report". Integrated Taxonomic Information System. Retrieved 2019-09-23.
- ^ doi:10.1016/S0020-7322(97)00030-5.)
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: CS1 maint: multiple names: authors list (link - ^ doi:10.1093/ee/26.6.1258.)
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: CS1 maint: multiple names: authors list (link - ^ S2CID 25161682.)
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: CS1 maint: multiple names: authors list (link - ^ a b c d e f g h i j k l m n o p q r s Kathirithamby, J. (2005). "Strepsiptera (Insecta) of Mexico - A Review". Monograph. 12: 103–118.
- ^ PMID 18817508.
- ^ doi:10.1111/bij.12585.)
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: CS1 maint: multiple names: authors list (link - ^ S2CID 30816756.)
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: CS1 maint: multiple names: authors list (link - S2CID 27737545.)
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: CS1 maint: multiple names: authors list (link - ^ PMID 15101403.)
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: CS1 maint: multiple names: authors list (link - S2CID 85267294.)
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: CS1 maint: multiple names: authors list (link - ^ doi:10.1093/ae/49.3.150.)
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: CS1 maint: multiple names: authors list (link
Further reading
- Pierce, W. Dwight (1909). "A monographic revision of the twisted winged insects comprising the order Strepsiptera Kirby". Bulletin of the United States National Museum. 66. hdl:10088/30423.
- Kathirithamby, Jeyaraney; Taylor, Steven J. (2005). "A new species of Halictophagus (Insecta: Strepsiptera: Halictophagidae) from Texas, and a checklist of Strepsiptera from the United States and Canada". Zootaxa. 1056 (1): 1–18. .
External links
- Media related to Caenocholax fenyesi at Wikimedia Commons
- "Caenocholax fenyesi species Information". BugGuide.net.
- "Caenocholax fenyesi". GBIF.