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| image = Orius minutus feeding on Trioza rhamni - ZooKeys-319-169-g002.jpeg | image = Orius minutus feeding on Trioza rhamni - ZooKeys-319-169-g002.jpeg
| image_caption = ''Orius minutus'' feeding on ''Trioza rhamni''. | image_caption = ''Orius minutus'' feeding on ''Trioza rhamni''.
| taxon = Orius minutus | genus = Orius
| species = minutus
| authority = (Wolff, 1811)<ref name="lh">{{cite journal |last1=Lattin |first1=J.D. |last2=Asquith |first2=A. |title=''Orius minutus'' (Linnaeus) in North America (Hemiptera: Heteroptera: Anthocoridae) |journal=Journal of the New York Entomological Society |date=1989 |volume=97 |pages=409-416 |url=http://www.jstor.org/stable/25009791}}</ref>}} | authority = (Wolff, 1811)<ref name="lh">{{cite journal |last1=Lattin |first1=J.D. |last2=Asquith |first2=A. |title=''Orius minutus'' (Linnaeus) in North America (Hemiptera: Heteroptera: Anthocoridae) |journal=Journal of the New York Entomological Society |date=1989 |volume=97 |issue=4 |pages=409–416 |jstor=25009791 |url=http://www.jstor.org/stable/25009791}}</ref>}}


'''''Orius minutus''''' is a ] species of ] in the family ].<ref name="lh" />. ''Orius minutus'' is naturally distributed throughout Europe, western Russia, North Africa, China, Japan, and Siberia<ref name="lh" /><ref name="tuda" /> The predatory bug was accidentally introduction into North America through plant material commerce and regular dispersal; the introduction of ''Orius minutus'' is generally considered beneficial to the agricultural industry.<ref name="lh" /><ref name="fr" /><ref name="three" /> ''Orius minutus'' is an important addition to the predator complex of many crops, and its role as a non-commercialized biological control agent highlights its unique contribution to pest management strategies.<ref name="lh" /><ref name="fr" /><ref name="three" /> '''''Orius minutus''''' is a ] species of ] in the family ].<ref name="lh" /> ''O. minutus'' is naturally distributed throughout Europe, western Russia, North Africa, China, Japan, and Siberia<ref name="lh" /><ref name="tuda" /> The predatory bug was accidentally introduction into North America through plant material commerce and regular dispersal; the introduction of ''O. minutus'' is generally considered beneficial to the agricultural industry.<ref name="lh" /><ref name="fr" /><ref name="three">{{cite journal |last1=Lan |first1=R. |last2=Ren |first2=X. |last3=Cao |first3=K. |last4=Zhou |first4=X. |last5=Jin |first5=L. |date=2022 |title=Demographic evaluation of the control potential of ''Orius minutus'' (Hemiptera: Anthocoridae) preying on ''Dendrothrips minowai Priesner'' (Thysanoptera: Thripidae) at different temperatures. |journal=Insects |volume=13 |issue=12 |page=1158 |doi=10.3390/insects13121158|doi-access=free |pmid=36555068 |pmc=9785448 }}</ref> ''O. minutus'' is an important addition to the predator complex of many crops, and its role as a non-commercialized ] highlights its unique contribution to ] strategies.<ref name="lh" /><ref name="fr" /><ref name="three" />

== Diagnostics== ==Diagnostics==
===Adults=== ===Adults===
Adult females of ''Orius minutus'' are larger (2.05-2.60 mm total length) and more broadly ovate (0.85-0.97 mm pronotal width) than males, who are slenderer (0.7-0.82 mm pronotal width) and possess thicker ]<ref name="lh" />. The heads range from dark brown to black, all sporting yellow antennae<ref name="lh" />. The ] and ] are brownish-grey to brownish-black, with the hardened forewings yellowish brown<ref name="lh" />. The underside and hind legs are dark brown to black, with the front and middle legs yellow<ref name="lh" />. Lengths of golden ] adorn the dorsal side of the insect<ref name="lh" />. Adult females of ''O. minutus'' are larger (2.05-2.60&nbsp;mm total length) and more broadly ovate (0.85-0.97&nbsp;mm pronotal width) than males, who are slenderer (0.7-0.82&nbsp;mm pronotal width) and possess thicker ].<ref name="lh" /> The heads range from dark brown to black, all sporting yellow antennae.<ref name="lh" /> The ] and ] are brownish-grey to brownish-black, with the hardened forewings yellowish brown.<ref name="lh" /> The underside and hind legs are dark brown to black, with the front and middle legs yellow.<ref name="lh" /> Lengths of golden ] adorn the dorsal side of the insect.<ref name="lh" />


===Nymphs=== ===Nymphs===
Fifth ] nymphs of ''Orius minutus'' are differentiated from other members of the genus ''Orius'' (e.g. '']'') by their broadly ovate body shape with one-third of the wing pad’s tip a much darker colour than the rest of the ]<ref name="lh" />. The maximum width of the pronotum is 0.70 mm or greater<ref name="lh" />. Fifth ] nymphs of ''O. minutus'' are differentiated from other members of the genus ''Orius'' (e.g. '']'') by their broadly ovate body shape with one-third of the wing pad's tip a much darker colour than the rest of the ].<ref name="lh" /> The maximum width of the pronotum is 0.70&nbsp;mm or greater.<ref name="lh" />


It is difficult to differentiate between earlier instars; many members of the genus ''Orius'' are a creamy white colour prior to their fifth instar<ref name="lh" />. However, ''Orius minutus'' are generally more robust and broader than other species<ref name="lh" />. Their eyes nearly touch the anterior margin of the pronotum<ref name="lh" />. The head is relatively short, with the protunum almost 1.5 times the width of the head<ref name="lh" />. It is difficult to differentiate between earlier instars; many members of the genus ''Orius'' are a creamy white colour prior to their fifth instar.<ref name="lh" /> However, ''O. minutus'' are generally more robust and broader than other species.<ref name="lh" /> Their eyes nearly touch the anterior margin of the pronotum.<ref name="lh" /> The head is relatively short, with the protunum almost 1.5 times the width of the head.<ref name="lh" />

⚫ ==Reproduction==


⚫ == Reproduction ==
===Mating=== ===Mating===
''Orius minutus'' females are functionally monandrous <ref name="mts">{{cite journal |last1=Arakawa|first1=T. |last2=Taniai |first2=K. |last3=Maeda|first3=T.|title= The mating systems of three species of minute piratebug, ''Orius sauteri'', ''O. minutus'', and ''O. strigicollis'' |journal= The Netherlands Entomological Society |date=2019 |volume=167|pages= 141–151 |doi=10.1111/eea.12740}}</ref>. Generally, females can not be inseminated by one mating<ref name="mts" />; only if the first mating fails will the females choose to mate with another male<ref name="mts" />. Females will refuse unwanted mating attempts by lifting their ] and struggling<ref name="mts" />; such behaviours suggest females control the functional monandry<ref name="mts" />. The number of unique male partners does not affect ], though mating with a single male decreases the hatching success of eggs<ref name="mts" />. Males are ] and can inseminate at least three females at a rate of one female per day<ref name="mts" />; the insemination ability of males persists for at least three copulations<ref name="mts" />. ''O. minutus'' females are functionally monandrous.<ref name="mts">{{cite journal |last1=Arakawa|first1=T. |last2=Taniai |first2=K. |last3=Maeda|first3=T.|title= The mating systems of three species of minute piratebug, ''Orius sauteri'', ''O. minutus'', and ''O. strigicollis'' |journal= The Netherlands Entomological Society |date=2019 |volume=167|issue=2 |pages= 141–151 |doi=10.1111/eea.12740|bibcode=2019EEApp.167..141A }}</ref> Generally, females can not be inseminated by one mating;<ref name="mts" /> only if the first mating fails will the females choose to mate with another male.<ref name="mts" /> Females will refuse unwanted mating attempts by lifting their ] and struggling;<ref name="mts" /> such behaviours suggest females control the functional monandry.<ref name="mts" /> The number of unique male partners does not affect ], though mating with a single male decreases the hatching success of eggs.<ref name="mts" /> Males are ] and can inseminate at least three females at a rate of one female per day;<ref name="mts" /> the insemination ability of males persists for at least three copulations.<ref name="mts" />


Unlike many members of Anthocoridae, ] does not occur within ''Orius minutus''<ref name="ti">{{cite journal |last1=Taniai |first1=K. |last2=Arakawa |first2=T. |last3=Maeda |first3=T. |title=Traumatic insemination is not the case in three ''Orius'' species (Heteroptera: Anthocoridae) |journal=PLoS One |date=2018 |volume=13 |page=e0206225 |doi=10.1371/journal.pone.0206225}}</ref>. Males instead employ extragenital insemination to transfer ] into the female’s body<ref name="ti" />. The male’s needle-like flagellum is inserted intersegmentally between the female’s abdominal segments without wounding or scarring her outer body<ref name="ti" />; the cone present on male genitalia assists in expanding the space between the female’s lower abdominal segments<ref name="ti" />. Males possess a partially ] copulatory tube to support and guide the flagellum into the female’s sperm pouch<ref name="ti" />. The spermatozoa can remain within the sperm pouch weeks after depositing several eggs, suggesting the sperm pouch functions as a long-term storage organ<ref name="ti" />. Females may be able to store spermatozoa for their entire lifetime, a consequence of functional monandry<ref name="ti" />. An extragenital structure called the ] is located at the fourth segment of the female body<ref name="ti" />. Underneath the ectospermalege is the ], a special endodermal pouch that receives the spermatozoa<ref name="ti" />. ''Orius minutus'' females lack ], instead possessing a pair of pseudospermatheca at the base of their lateral ]<ref name="ti" />; the pseudospermatheca receives the spermatozoa, which transfers from the mesospermalege in the ]<ref name="ti" />. Unlike many members of Anthocoridae, ] does not occur within ''O. minutus''.<ref name="ti">{{cite journal |last1=Taniai |first1=K. |last2=Arakawa |first2=T. |last3=Maeda |first3=T. |title=Traumatic insemination is not the case in three ''Orius'' species (Heteroptera: Anthocoridae) |journal=PLOS ONE |date=2018 |volume=13 |issue=12 |page=e0206225 |doi=10.1371/journal.pone.0206225|doi-access=free |pmid=30517107 |pmc=6281218 |bibcode=2018PLoSO..1306225T }}</ref> Males instead employ extragenital insemination to transfer ] into the female's body.<ref name="ti" /> The male's needle-like flagellum is inserted intersegmentally between the female's abdominal segments without wounding or scarring her outer body;<ref name="ti" /> the cone present on male genitalia assists in expanding the space between the female's lower abdominal segments.<ref name="ti" /> Males possess a partially ] copulatory tube to support and guide the flagellum into the female's sperm pouch.<ref name="ti" /> The spermatozoa can remain within the sperm pouch weeks after depositing several eggs, suggesting the sperm pouch functions as a long-term storage organ.<ref name="ti" /> Females may be able to store spermatozoa for their entire lifetime, a consequence of functional monandry.<ref name="ti" /> An extragenital structure called the ] is located at the fourth segment of the female body.<ref name="ti" /> Underneath the ectospermalege is the ], a special endodermal pouch that receives the spermatozoa.<ref name="ti" /> ''O. minutus'' females lack ], instead possessing a pair of pseudospermatheca at the base of their lateral ];<ref name="ti" /> the pseudospermatheca receives the spermatozoa, which transfers from the mesospermalege in the ].<ref name="ti" />


===Pheromones=== ===Pheromones===
Contact ] are present within the trails of ''Orius minutus''<ref name="ph">{{cite journal |last1=Maeda |first1=T. |last2=Fujiwara-Tsuji |first2=N. |last3=Yasui |first3=H. |last4=Matsuyama |first4=S. |title=Female sex pheromone in trails of the minute pirate bug, ''Orius minutus'' (L) |journal=Journal of Chemical Ecology |date=2016 |volume=442 |page=433-443 |doi=10.1007/s10886-016-0702-2}}</ref>. Trails left by mature virgin females aid males in locating a mate<ref name="ph" />. Contact ] are present within the trails of ''O. minutus''.<ref name="ph">{{cite journal |last1=Maeda |first1=T. |last2=Fujiwara-Tsuji |first2=N. |last3=Yasui |first3=H. |last4=Matsuyama |first4=S. |title=Female sex pheromone in trails of the minute pirate bug, ''Orius minutus'' (L) |journal=Journal of Chemical Ecology |date=2016 |volume=442 |issue=5 |pages=433–443 |doi=10.1007/s10886-016-0702-2|pmid=27184908 |bibcode=2016JCEco..42..433M }}</ref> Trails left by mature virgin females aid males in locating a mate.<ref name="ph" /> Males will linger on leaves exposed to trails left by mature virgin females, allowing males to locate ] females who had recently deposited trails on the plant.<ref name="ph" /> Males will respond to the trails regardless of their mating experience, though only trails from mature females arrest males.<ref name="ph" /> Females respond with weak arrestment to the leaves walked on by males, which could further assist in finding a mate.<ref name="ph" />
Males will linger on leaves exposed to trails left by mature virgin females, allowing males to locate ] females who had recently deposited trails on the plant<ref name="ph" />. Males will respond to the trails regardless of their mating experience, though only trails from mature females arrest males<ref name="ph" />. Females respond with weak arrestment to the leaves walked on by males, which could further assist in finding a mate<ref name="ph" />.


=== Effect of temperature === ===Effect of temperature===
Although ''Orius minutus'' have a higher rate of reproduction at temperatures between 17-26° C, they experience a decrease in lifetime fecundity at and above temperatures of 26° C <ref name="two">{{cite journal |last1=Kakimoto |first1=K. |last2=Urano |first2=S. |last3=Noda |first3=T. |last4=Matuo |first4=L. |last5=Sakamaki |first5=Y. |last6=Tsuda |first6=K. |last7=Kusigemati |first7=K. |title=Comparison of the reproductive potential of three ''Orius'' species, ''O.strigicollis'', ''O. sauteri'', and ''O. minutus'' (Heteroptera : Anthocoridae), using eggs of the Mediterranean flour moth as a food source. |journal=Applied Entomology and Zoology |date=2005 |volume=40 |pages=247–255 |doi=10.1303/aez.2005.247}}</ref>; the reduction in fecundity at higher temperatures suggests that ''Orius minutus'' are disadvantaged when experiencing wide ranges of temperatures <ref name="three">{{cite journal |last1=Lan |first1=R. |last2=Ren |first2=X. |last3=Cao |first3=K. |last4=Zhou |first4=X. |last5=Jin |first5=L. |title=Demographic evaluation of the control potential of ''Orius minutus'' (Hemiptera: Anthocoridae) preying on ''Dendrothrips minowai Priesner'' (Thysanoptera: Thripidae) at different temperatures. |journal=Insects |date=2022 |volume=12 |page=1158 |doi=10.3390/insects13121158}}</ref>. Although ''O. minutus'' have a higher rate of reproduction at temperatures between 17 and 26&nbsp;°C, they experience a decrease in lifetime fecundity at and above temperatures of 26&nbsp;°C;<ref name="two">{{cite journal |last1=Kakimoto |first1=K. |last2=Urano |first2=S. |last3=Noda |first3=T. |last4=Matuo |first4=L. |last5=Sakamaki |first5=Y. |last6=Tsuda |first6=K. |last7=Kusigemati |first7=K. |date=2005 |title=Comparison of the reproductive potential of three ''Orius'' species, ''O.strigicollis'', ''O. sauteri'', and ''O. minutus'' (Heteroptera : Anthocoridae), using eggs of the Mediterranean flour moth as a food source. |journal=Applied Entomology and Zoology |volume=40 |issue=2 |pages=247–255 |doi=10.1303/aez.2005.247|bibcode=2005AppEZ..40..247K }}</ref> the reduction in fecundity at higher temperatures suggests that ''O. minutus'' are disadvantaged when experiencing wide ranges of temperatures.<ref name="three" />


== Life history == ==Life history==
''Orius minutus'' females ] fertilized, usually emerging from ] in the early spring<ref name="lh" /><ref name="two" /><ref name="fifty">{{cite journal |last1=Collyer |first1=E. |title=Biology of some predatory insects and mites associated with the fruit tree red spider mite (''Metatetranychus ulmi'' (Koch)) in south-eastern England. II. Some important predators of the mite. |journal=Journal of Horticultural Science |date=1953 |volume=28 |pages=85-97}}</ref>. Males can hibernate but are unlikely to survive the winter due to their lack of ] and inadequate ] accumulation<ref name="lh" /><ref name="ito">{{cite journal |last1=Ito |first1=K. |last2=Nakata |first2=Y. |title=Diapause and survival in winter in two species of predatory bugs, ''Orius sauteri'' and ''Orius minutus''. |journal=Entomologia Experimentalis et Applicata |date=1998 |volume=89 |pages=271-276 |doi=10.1046/j.1570-7458.1998.00408.x}}</ref>. Shortly after hibernation ends, eggs are deposited onto the base of developing flower buds or the ] on the bottom of leaves<ref name="lh" /><ref name="ger">{{cite journal |last1=Fulmek |first1=L. |title=Kenntnis der entwicklungsstadien von ''Triphleps minuta'' L. (Anthocoridae, Hemiptera, Heteroptera). |journal=Insektenbiol |date=1930 |volume=25 |pages=82-88}}</ref>. ''O. minutus'' females ] fertilized, usually emerging from ] in the early spring.<ref name="lh" /><ref name="two" /><ref name="fifty">{{cite journal |last1=Collyer |first1=E. |title=Biology of some predatory insects and mites associated with the fruit tree red spider mite (''Metatetranychus ulmi'' (Koch)) in south-eastern England. II. Some important predators of the mite. |journal=Journal of Horticultural Science |date=1953 |volume=28 |pages=85–97|doi=10.1080/00221589.1953.11513772 }}</ref> Males can hibernate but are unlikely to survive the winter due to their lack of ] and inadequate ] accumulation.<ref name="lh" /><ref name="ito">{{cite journal |last1=Ito |first1=K. |last2=Nakata |first2=Y. |title=Diapause and survival in winter in two species of predatory bugs, ''Orius sauteri'' and ''Orius minutus''. |journal=Entomologia Experimentalis et Applicata |date=1998 |volume=89 |pages=271–276 |doi=10.1046/j.1570-7458.1998.00408.x}}</ref> Shortly after hibernation ends, eggs are deposited onto the base of developing flower buds or the ] on the bottom of leaves.<ref name="lh" /><ref name="ger">{{cite journal |last1=Fulmek |first1=L. |title=Kenntnis der entwicklungsstadien von ''Triphleps minuta'' L. (Anthocoridae, Hemiptera, Heteroptera). |journal=Insektenbiol |date=1930 |volume=25 |pages=82–88}}</ref>


''Orius minutus'' has five nymphal instars<ref name="lh" />. The developmental time from egg to adult depends on temperature and location, though adulthood is generally reached within 24 to 30 days <ref name="lh" /><ref name="fifty" />.  ''Orius minutus'' produce at least two generations annually, though up to four generations can be produced under ideal conditions <ref name="lh" /><ref name="fifty"/>. Adults collected from early spring and mid-autumn suggest ''Orius minutus'' is ]<ref name="lh" /><ref name="fifty"/>. ''O. minutus'' has five nymphal instars.<ref name="lh" /> The developmental time from egg to adult depends on temperature and location, though adulthood is generally reached within 24 to 30 days.<ref name="lh" /><ref name="fifty" /> ''O. minutus'' produce at least two generations annually, though up to four generations can be produced under ideal conditions.<ref name="lh" /><ref name="fifty"/> Adults collected from early spring and mid-autumn suggest ''O. minutus'' is ].<ref name="lh" /><ref name="fifty"/>


==Diet== ==Diet==
''Orius minutus'' are generalist predators of small insects, including ], ], ], ] and ]<ref name="lh"/><ref name="fr">{{cite journal |last1=Rahman |first1=M.A. |last2=Sarker |first2=S. |last3=Ham |first3=E. |last4=Lee |first4=J.S. |last5=Lim |first5=U.T. |title=Prey preference of ''Orius minutus'' and its functional response in comparison that of O. laevigatus, on ''Tetranychus urticae''. |journal=Journal of Asia-Pacific Entomology |date=2022 |volume=25 |page=101912 |doi=10.1016/j.aspen.2022.101912}}</ref>. Though chiefly predacious, Orius minutus may occasionally feed on plant material and sap (e.g. the fluid produced by '']'').<ref name="lh" /> ''O. minutus'' are generalist predators of small insects, including ], ], ], ] and ].<ref name="lh"/><ref name="fr">{{cite journal |last1=Rahman |first1=M.A. |last2=Sarker |first2=S. |last3=Ham |first3=E. |last4=Lee |first4=J.S. |last5=Lim |first5=U.T. |title=Prey preference of ''Orius minutus'' and its functional response in comparison that of O. laevigatus, on ''Tetranychus urticae''. |journal=Journal of Asia-Pacific Entomology |date=2022 |volume=25 |issue=2 |page=101912 |doi=10.1016/j.aspen.2022.101912|bibcode=2022JAsPE..2501912R }}</ref> Though chiefly predacious, O. minutus may occasionally feed on plant material and sap (e.g. the fluid produced by '']'').<ref name="lh" />


== Behaviour == ==Behaviour==


=== Foraging and flying=== ===Foraging and flying===


Though ''Orius minutus'' will initially fly relatively randomly, the discovery of prey patches shifts their dispersal activity into foraging activity<ref name="tuda">{{cite journal |last1=Tuda |first1=M. |last2=Shima |first2=K. |title=Relative importance of weather and density dependence on the dispersal and on-plant activity of the predator ''Orius minutus'' |journal=Popular Ecology |date=2002 |volume=44 |pages=251–257 |doi=10.1007/s101440200028}}</ref>; they are highly reluctant to leave patches with a high prey density<ref name="tuda" />. ] significantly influence this behaviour, with increased plant foraging behaviours correlating with high solar radiation and low humidity<ref name="tuda" />.  Both males and females are ] fliers, though females engage in less flight activity than males<ref name="tuda" />. Though ''O. minutus'' initially flies out in random directions, the discovery of prey patches shifts their dispersal into foraging activity;<ref name="tuda">{{cite journal |last1=Tuda |first1=M. |last2=Shima |first2=K. |title=Relative importance of weather and density dependence on the dispersal and on-plant activity of the predator ''Orius minutus'' |journal=Popular Ecology |date=2002 |volume=44 |issue=3 |pages=251–257 |doi=10.1007/s101440200028|bibcode=2002PopEc..44..251T }}</ref> individuals that discover patches with a high prey density are hesitant to fly out from the patches.<ref name="tuda" /> ] significantly influence this behaviour, with increased plant foraging behaviours correlating with high solar radiation and low humidity.<ref name="tuda" /> Both males and females are ] fliers, though females engage in less flight activity than males.<ref name="tuda" />


=== Diapause === ===Diapause===
The critical ] for inducing diapause is between 14.5-9.5D and 15L-9D at 22°C, corresponding to late summer in many regions occupied by ''Orius minutus''<ref name="ito"/>. During diapause, the insects do not copulate, and the female’s ovaries remain small until the following spring<ref name="ito"/>. Adult females do not enter diapause regardless of short day length if their nymphal stages were spent under long day length <ref name="ito"/>. Adult diapause is not induced in males due to a shortage of lipid accumulation<ref name="ito"/>. The critical ] for inducing diapause is between 14.5-9.5D and 15L-9D at 22&nbsp;°C, corresponding to late summer in many regions occupied by ''O. minutus''.<ref name="ito"/> During diapause, the insects do not copulate, and the female's ovaries remain small until the following spring.<ref name="ito"/> Adult females do not enter diapause regardless of short day length if their nymphal stages were spent under long day length.<ref name="ito"/> Adult diapause is not induced in males due to a shortage of lipid accumulation.<ref name="ito"/>


==References== ==References==
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{{Taxonbar|from=Q9362374}} {{Taxonbar|from=Q9362374}}

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Latest revision as of 21:56, 16 December 2024

Species of minute pirate bug

Orius minutus
Orius minutus feeding on Trioza rhamni.
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Suborder: Heteroptera
Family: Anthocoridae
Genus: Orius
Species: O. minutus
Binomial name
Orius minutus
(Wolff, 1811)

Orius minutus is a Palearctic species of minute pirate bug in the family Anthocoridae. O. minutus is naturally distributed throughout Europe, western Russia, North Africa, China, Japan, and Siberia The predatory bug was accidentally introduction into North America through plant material commerce and regular dispersal; the introduction of O. minutus is generally considered beneficial to the agricultural industry. O. minutus is an important addition to the predator complex of many crops, and its role as a non-commercialized biological control agent highlights its unique contribution to pest management strategies.

Diagnostics

Adults

Adult females of O. minutus are larger (2.05-2.60 mm total length) and more broadly ovate (0.85-0.97 mm pronotal width) than males, who are slenderer (0.7-0.82 mm pronotal width) and possess thicker antennae. The heads range from dark brown to black, all sporting yellow antennae. The pronotum and scutellum are brownish-grey to brownish-black, with the hardened forewings yellowish brown. The underside and hind legs are dark brown to black, with the front and middle legs yellow. Lengths of golden setae adorn the dorsal side of the insect.

Nymphs

Fifth instar nymphs of O. minutus are differentiated from other members of the genus Orius (e.g. O. tristicolor) by their broadly ovate body shape with one-third of the wing pad's tip a much darker colour than the rest of the dorsum. The maximum width of the pronotum is 0.70 mm or greater.

It is difficult to differentiate between earlier instars; many members of the genus Orius are a creamy white colour prior to their fifth instar. However, O. minutus are generally more robust and broader than other species. Their eyes nearly touch the anterior margin of the pronotum. The head is relatively short, with the protunum almost 1.5 times the width of the head.

Reproduction

Mating

O. minutus females are functionally monandrous. Generally, females can not be inseminated by one mating; only if the first mating fails will the females choose to mate with another male. Females will refuse unwanted mating attempts by lifting their ovipositors and struggling; such behaviours suggest females control the functional monandry. The number of unique male partners does not affect fecundity, though mating with a single male decreases the hatching success of eggs. Males are polygamous and can inseminate at least three females at a rate of one female per day; the insemination ability of males persists for at least three copulations.

Unlike many members of Anthocoridae, traumatic insemination does not occur within O. minutus. Males instead employ extragenital insemination to transfer spermatozoa into the female's body. The male's needle-like flagellum is inserted intersegmentally between the female's abdominal segments without wounding or scarring her outer body; the cone present on male genitalia assists in expanding the space between the female's lower abdominal segments. Males possess a partially sclerotized copulatory tube to support and guide the flagellum into the female's sperm pouch. The spermatozoa can remain within the sperm pouch weeks after depositing several eggs, suggesting the sperm pouch functions as a long-term storage organ. Females may be able to store spermatozoa for their entire lifetime, a consequence of functional monandry. An extragenital structure called the ectospermalege is located at the fourth segment of the female body. Underneath the ectospermalege is the mesospermalege, a special endodermal pouch that receives the spermatozoa. O. minutus females lack spermatheca, instead possessing a pair of pseudospermatheca at the base of their lateral oviducts; the pseudospermatheca receives the spermatozoa, which transfers from the mesospermalege in the hemolymph.

Pheromones

Contact sex pheromones are present within the trails of O. minutus. Trails left by mature virgin females aid males in locating a mate. Males will linger on leaves exposed to trails left by mature virgin females, allowing males to locate conspecific females who had recently deposited trails on the plant. Males will respond to the trails regardless of their mating experience, though only trails from mature females arrest males. Females respond with weak arrestment to the leaves walked on by males, which could further assist in finding a mate.

Effect of temperature

Although O. minutus have a higher rate of reproduction at temperatures between 17 and 26 °C, they experience a decrease in lifetime fecundity at and above temperatures of 26 °C; the reduction in fecundity at higher temperatures suggests that O. minutus are disadvantaged when experiencing wide ranges of temperatures.

Life history

O. minutus females overwinter fertilized, usually emerging from hibernation in the early spring. Males can hibernate but are unlikely to survive the winter due to their lack of diapause and inadequate lipid accumulation. Shortly after hibernation ends, eggs are deposited onto the base of developing flower buds or the midrib on the bottom of leaves.

O. minutus has five nymphal instars. The developmental time from egg to adult depends on temperature and location, though adulthood is generally reached within 24 to 30 days. O. minutus produce at least two generations annually, though up to four generations can be produced under ideal conditions. Adults collected from early spring and mid-autumn suggest O. minutus is bivoltine.

Diet

O. minutus are generalist predators of small insects, including aphids, mites, thrips, whiteflies and scales. Though chiefly predacious, O. minutus may occasionally feed on plant material and sap (e.g. the fluid produced by Eryngium campestre).

Behaviour

Foraging and flying

Though O. minutus initially flies out in random directions, the discovery of prey patches shifts their dispersal into foraging activity; individuals that discover patches with a high prey density are hesitant to fly out from the patches. Abiotic factors significantly influence this behaviour, with increased plant foraging behaviours correlating with high solar radiation and low humidity. Both males and females are diurnal fliers, though females engage in less flight activity than males.

Diapause

The critical photoperiod for inducing diapause is between 14.5-9.5D and 15L-9D at 22 °C, corresponding to late summer in many regions occupied by O. minutus. During diapause, the insects do not copulate, and the female's ovaries remain small until the following spring. Adult females do not enter diapause regardless of short day length if their nymphal stages were spent under long day length. Adult diapause is not induced in males due to a shortage of lipid accumulation.

References

  1. ^ Lattin, J.D.; Asquith, A. (1989). "Orius minutus (Linnaeus) in North America (Hemiptera: Heteroptera: Anthocoridae)". Journal of the New York Entomological Society. 97 (4): 409–416. JSTOR 25009791.
  2. ^ Tuda, M.; Shima, K. (2002). "Relative importance of weather and density dependence on the dispersal and on-plant activity of the predator Orius minutus". Popular Ecology. 44 (3): 251–257. Bibcode:2002PopEc..44..251T. doi:10.1007/s101440200028.
  3. ^ Rahman, M.A.; Sarker, S.; Ham, E.; Lee, J.S.; Lim, U.T. (2022). "Prey preference of Orius minutus and its functional response in comparison that of O. laevigatus, on Tetranychus urticae". Journal of Asia-Pacific Entomology. 25 (2): 101912. Bibcode:2022JAsPE..2501912R. doi:10.1016/j.aspen.2022.101912.
  4. ^ Lan, R.; Ren, X.; Cao, K.; Zhou, X.; Jin, L. (2022). "Demographic evaluation of the control potential of Orius minutus (Hemiptera: Anthocoridae) preying on Dendrothrips minowai Priesner (Thysanoptera: Thripidae) at different temperatures". Insects. 13 (12): 1158. doi:10.3390/insects13121158. PMC 9785448. PMID 36555068.
  5. ^ Arakawa, T.; Taniai, K.; Maeda, T. (2019). "The mating systems of three species of minute piratebug, Orius sauteri, O. minutus, and O. strigicollis". The Netherlands Entomological Society. 167 (2): 141–151. Bibcode:2019EEApp.167..141A. doi:10.1111/eea.12740.
  6. ^ Taniai, K.; Arakawa, T.; Maeda, T. (2018). "Traumatic insemination is not the case in three Orius species (Heteroptera: Anthocoridae)". PLOS ONE. 13 (12): e0206225. Bibcode:2018PLoSO..1306225T. doi:10.1371/journal.pone.0206225. PMC 6281218. PMID 30517107.
  7. ^ Maeda, T.; Fujiwara-Tsuji, N.; Yasui, H.; Matsuyama, S. (2016). "Female sex pheromone in trails of the minute pirate bug, Orius minutus (L)". Journal of Chemical Ecology. 442 (5): 433–443. Bibcode:2016JCEco..42..433M. doi:10.1007/s10886-016-0702-2. PMID 27184908.
  8. ^ Kakimoto, K.; Urano, S.; Noda, T.; Matuo, L.; Sakamaki, Y.; Tsuda, K.; Kusigemati, K. (2005). "Comparison of the reproductive potential of three Orius species, O.strigicollis, O. sauteri, and O. minutus (Heteroptera : Anthocoridae), using eggs of the Mediterranean flour moth as a food source". Applied Entomology and Zoology. 40 (2): 247–255. Bibcode:2005AppEZ..40..247K. doi:10.1303/aez.2005.247.
  9. ^ Collyer, E. (1953). "Biology of some predatory insects and mites associated with the fruit tree red spider mite (Metatetranychus ulmi (Koch)) in south-eastern England. II. Some important predators of the mite". Journal of Horticultural Science. 28: 85–97. doi:10.1080/00221589.1953.11513772.
  10. ^ Ito, K.; Nakata, Y. (1998). "Diapause and survival in winter in two species of predatory bugs, Orius sauteri and Orius minutus". Entomologia Experimentalis et Applicata. 89: 271–276. doi:10.1046/j.1570-7458.1998.00408.x.
  11. Fulmek, L. (1930). "Kenntnis der entwicklungsstadien von Triphleps minuta L. (Anthocoridae, Hemiptera, Heteroptera)". Insektenbiol. 25: 82–88.
Taxon identifiers
Orius minutus
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