Megacopta cribraria
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Megacopta cribraria |
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| Megacopta cribraria | ||||||||||||
| ( Fabricius , 1798) |
Megacopta cribraria is a species of bug from the family of ball bugs (Plataspididae). The species, which was originally widespread in Asia, was introduced by humans to the United States of America, where it is considered a pest in agriculture, as it feeds primarily on legumes (Fabaceae), with kudzu ( Pueraria montana ) being the most important food crop. The species is probably conspecific with the very similar species Megacopta punctatissima , that is, it is probably the same biological species.
features
The bugs are 3.5 to 6.0 millimeters long and have a rounded, rectangular body. Females are slightly larger than males and can be distinguished from them by the end of their abdomen, among other things. In the females this is rounded, whereas in the males a small indentation can be seen. The ventral side is black and moderately dotted. In females, the underside of the abdomen is broadly pale laterally; in males, this coloration is limited to the second and third visible sternite . The fourth to sixth segment is black with them and dense with bristle hairs ( setae ) on the sides . The otherwise light brown to olive green body of the animals is provided with numerous dark spots. The head is flat. The second link of the antennae is only about a third the length of the third segment or is even shorter. The scutellum is typically enlarged for a member of the Plataspididae and covers the wings and large parts of the abdomen. It is 1.5 times as wide as it is long and truncated at the back or very broadly rounded. The widest point is in the rearmost quarter. The base of the label has an obliquely elongated area which is delimited by a clearly indented line. The enlarged tarsi are two-part. The rails ( tibia ) carry setae and they lack strong thorns.
The elongated oval eggs are 0.8 to 0.9 by 0.4 to 0.5 millimeters in size. They are initially white, but turn off-white to pale salmon-colored, with darker lines lengthways. The eggs are truncated at one end and have a ring of rough appendages. The nymphs are initially reddish-brown, in the second and third stages yellowish-green and later greenish-brown. In the fifth stage they are four to five millimeters long and have an oval body. They are light to dark brown and hairy. The lateral edges of the thorax and abdomen are somewhat flattened.
Occurrence
The natural range of the species covers large parts of Asia (Pakistan, India, Sri Lanka, China, Taiwan, Vietnam, Myanmar, Thailand, Japan, Korea, Indonesia, Malaysia), New Caledonia and Australia.
The first sighting of Megacopta cribraria in the United States was in Georgia in October 2009, as the first species of the family in the New World. After the species was detected in nine counties in the northeast in 2009, it was found in 80 counties in Georgia and in 16 others in South Carolina in 2010. In the meantime (as of 2012) the species is distributed in six southeastern states of the USA: Alabama, in northern Florida, Georgia, South and North Carolina and in southern Virginia. DNA studies on two of their gut symbionts ( Candidatus Ishikawaella capsulata and Wolbachia ) show that the spread originated in a single female line from Japan.
Way of life
The animals are attracted to bright colors, especially white and yellow. Like other bedbugs, they can secrete a foul-smelling secretion as a defense. Both the nymphs and the adults feed on the underside of the leaves and on the branches of their food plants. They cause unnatural plant growth and dead areas on the plants.
The main food plants of Megacopta cribraria are legumes (Fabaceae), with kudzu ( Pueraria montana ) being the most important food plant. The bugs have also been found in numerous other species or genera of this family: Helmet bean ( Lablab purpureus ), soybean ( Glycine max ), pigeon pea ( Cajanus cajan ), phaseolus , such as common bean ( Phaseolus vulgaris ) and lima bean ( Phaseolus lunatus ), Vigna , as mung bean ( Vigna radiata ), adzuki bean ( Vigna angularis ), and black gram ( Vigna mungo ), Sesbania grandiflora ( Sesbania grandiflora ), guar bean ( Cyamopsis tetragonolobus ), Lespedeza cyrtobotrya , Astragalus sinicus , Indigofera , Pongamia pinnata and velvet bean ( Mucuna pruriens ). In addition, the bug species is also mentioned in the literature on many plant species from other families, which are probably mostly misleading individual finds or errors. The species can only develop on two of the plant species mentioned in the literature that do not belong to the legumes. The development of the nymphs takes longer and females are less fertile. It is Crossandra infundibuliformis (family Acanthaceae (Acanthaceae)), and Gossypium hirsutum (a species of the genus cotton from the family of the Malvaceae (Malvaceae)).
In its original homeland, the species is not a relevant agricultural pest. However, it occurs as a pest on helm bean , sesbania , beans and soybeans. In the case of soybeans, depending on the degree of infestation, crop failures of 1 to 50%, in the USA an average of 18%, are documented. It is conceivable that Megacopta cribraria could be used in the USA to combat kudzu, which is considered a massively invasive neophyte there . Plants infested with bugs have a third less biomass than normal. However, since the bugs tend to accumulate in aggregations on and around houses, they can in turn be an even greater nuisance there. On the one hand, they are annoying because of the large number of individuals and, on the other hand, because the secretion they release has a strong smell and stains clothing and plastic surfaces. The animals also cause an allergic reaction on human skin. There is also a risk that the species will also appear as a pest on bean crops in the USA.
development
The females lay their eggs on the underside of the leaves of the food plants in a clutch that consists of two, sometimes three parallel rows of an average of 15 to 16 eggs. A female lays a total of 26 to 274 eggs. Dark capsules containing the animals' symbiotic bacteria are placed underneath the eggs and are ingested by the hatching nymphs. The nymphs go through five stages. The development from egg to adult animal takes 24 to 56 days. The adults then have a life expectancy of 23 to 77 days. In its original homeland, the bug develops one to three generations per year. From April to July the animals come together in large mating aggregations and then colonize their food plants, on which they can be found from August to October. Females tend to react more willing to mate to the mutual advertising of the males in aggregations than they are in comparison to individual advertising males. The bugs hibernate as adults under dead plant parts, bark or on protected parts of houses and the like. In the warmer areas they occur all year round.
Specialized enemies
In the USA, despite extensive breeding, no parasitoids of eggs or larvae of the species have been detected (an individual observation of Phasia robertsonii (Townsend), family Tachinidae in adults ), and frequent and generalistic egg parasitoids of the closely related Pentatomidae ignored the eggs. In natural range, especially in Japan and China, are Paratelenomus saccharalis (Dodd) (also known as Trissolcus sp. Reported) and Ooencyrtus nezarae Ishii, both family Platygastridae (a family of jewel wasps ), the main Eiparasitoide with attack rates between about 20 and 80 %, often over 50% of the eggs. The use of Paratelenomus saccharalis , which specifically infects plataspid eggs, for biological pest control of the species is currently being considered because there are no naturally occurring plataspids in America. Another, less important egg parasitoid is about Encarsia boswelli ( syn.Dirphys boswelli , Encarsiella boswelli , family Aphelinidae ), there is also information about a number of other Encyrtidae and Platygastridae with mostly uncertain species identification. In addition, the bug species is attacked by the fungus Beauveria bassiana in India and America .
Taxonomy and systematics
Megacopta cribraria was first described by Johann Christian Fabricius in 1798 as Cimex cribrarius . In 1843 the species was placed in the genus Coptosoma by Amyot and Serville and finally in the genus Megacopta by Hsiao and Ren in 1977 , to which it is still assigned today. Megacopta punctatissima is a very similar species, which is mainly differentiated based on its color and size. It is darker and slightly larger than Megacopta cribraria . There are apparently no genital morphological differences. The two species also produce reproductive hybrids , but have never been synonymous , although it has been suggested that they are one and the same species. Hosokawa et al. (2007) consider the division into two species to be justified, although they also confirm hybridization, since Megacopta punctatissima is a common pest on soybeans in Japan, whereas Megacopta cribraria occurs only in the southwest of the country and rarely causes damage to agriculture and then not caused by soybean. The two species differ in their symbiotic intestinal bacteria. Unlike those of Megacopta cribraria , those of Megacopta punctatissima are able to break down legumes so that they can be used by the bugs, which results in the different preferences of the food plants. If the intestinal bacteria of Megacopta punctatissima are made available to Megacopta cribraria , they can also feed on legumes, as do the animals from the USA, which can, however, be unequivocally identified as Megacopta cribraria . The differences shown could therefore only be those caused by the different symbionts, and thus the conspecificity of the two species is in the room. Using the DNA signature, which corresponds to animals from Japan, the American animals would actually have to be assigned to M. punctatissima if the species were actually different.
Synonyms of the kind are:
- Cimex cribraria Fabricius, 1798
- Tetyra cribraria Fabricius, 1803
- Thyreocoris cribarius Burmeister, 1835
- Coptosoma cribrarium Amyot & Serville, 1843
- Coptosoma xanthochlora Walker, 1867
supporting documents
Individual evidence
- ↑ a b c d e f g h i j k l J. E. Eger Jr., LM Ames, DR Suiter, TM Jenkins, DA Rider, SE Halbert: Occurrence of the Old World bug Megacopta cribraria (Fabricius) (Heteroptera: Plataspidae) in Georgia: a serious home invader and potential legume pest . In: Insecta Mundi . No. 0121, 2010, pp. 1-11.
- ↑ a b c d e f g Megacopta cribraria : A New Invasive Insect Pest Threatening US Agricultural Production and Export Markets ( English , PDF; 497 kB) Retrieved June 30, 2013.
- ↑ a b c d University of Florida, IFAS: Featured Creatures ( English ) Retrieved June 30, 2013.
- ↑ a b c d John R. Ruberson, Keiji Takasu, G. David Buntin, Joe E. Eger Jr., Wayne A. Gardner, Jeremy K. Greene, Tracie M. Jenkins, Walker A. Jones, Dawn M. Olson, Phillip M. Roberts, Daniel R. Suiter, Michael D. Toews (2013): From Asian curiosity to eruptive American pest: Megacopta cribraria (Hemiptera: Plataspidae) and prospects for its biological control. Applied Entomology and Zoology Volume 48, Issue 1: 3-13. doi : 10.1007 / s13355-012-0146-2
