Trichogramma

**赤眼蜂屬**（學名： Trichogramma）是膜翅目細腰亞目寄生蜂下目之下的小蜂總科赤眼蜂科的成員之一，其物種皆為多食性的微小擬寄生物，寄生於其牠昆蟲的蟲卵中。赤眼蜂屬是赤眼蜂科約 80 個屬的其中一個，在全世界包括超過 200 個物種。成蟲大多小於 1 毫米，會產卵於宿主卵內，幼蟲取食卵黃、化蛹並引發宿主死亡。成蟲羽化後咬破寄主卵殼而出。

儘管現時在全世界有多種用於生物防治的物種，本屬物種仍然是研究得最詳盡的一類，有超過一千份相關的文獻與本屬物種相關，也是目前世上於生物防治中 最常用的物種。 _Trichogramma_ spp. are unique in approaching the size limit of how small an insect can be, which would be determined by how few neurons they can fit in their central nervous systems, yet exhibiting a complex behavior to sustain their lives. These wasps have less than 10,000 neurons, which is 1/100th that of the next smallest insect.

## 寄生性

雌性成蟲會通過化學和視覺信號來找到用來作為宿主的卵，比如卵大小和顏色。在她找到合適的卵後，其將會試圖通過她的產卵器和對卵殼的敲擊來判別這個卵是否之前已經被寄生過了。雌性赤眼蜂也會通過敲擊來判別目標被寄生卵的大小和質量以決定赤眼蜂在被寄生卵內的產卵數量。一個雌性赤眼蜂一天最多可以在十個被寄生卵上產卵。

## 辨識

本屬物種體型細小，構造上亦單一，使物種間的分辨頗困難。由於雌性相對來說體型較小，分類學家一般通過辨別雄性觸角和生殖器的方式來辨別不同物種。

Charles V. Riley 在 1871 年於北美第一種對赤眼蜂屬下的物種進行描述。他將從總督蝶卵中爬出來的小蜂稱為 _Trichogramma minutum_。在生物分類學中，首個採集的標本是十分重要的，因為其被用作繼續描述這個物種的基礎，但是它丟失了。Riley 後來在 1879 年又描述了第二種叫做 _Trichogramma pretiosum_ 的赤眼蜂，但是其樣本也丟了。為了更正這些錯誤，昆蟲學家返回了 Riley 原本找到這兩個物種的地方並收集了新的範本。現在這些範本被完好地存放在美國史密森尼學會。當前赤眼蜂屬的物種超過兩百種，但是在 1960 年的時候只有大概 40 種赤眼蜂被描述。

## 赤眼蜂屬物種體內的沃爾巴克氏體

赤眼蜂屬物種體內有沃爾巴克氏體（_Wolbachia_），是一種分佈廣泛的細菌，專門感染昆蟲的內臟，特別是生殖系統的器官。這些沃爾巴克氏體在感染了昆蟲後，會改變其宿主交配時的成功率。
Through a series of manipulations, _Wolbachia-_infected hosts transmit this intracellular bacterium to uninfected individuals. These manipulations include male killing (increasing ratio of infected females that can reproduce), feminization (males become fertile females), 單性生殖，and cytoplasmic incompatibility. Horizontal transfer of parthenogenesis-inducing _Wolbachia_, which has been observed in _Trichogramma_ wasps, causes infected females to asexually produce fertile females and nonfunctional males. The effects of this include potential speciation of _Trichogramma_, if _Wolbachia_ is maintained long enough for genetic divergence to occur and for a new species of asexual wasps to become reproductively isolated.

Transmission of the bacterium through horizontal transfer has been observed within the same species and among different species of _Trichogramma_, including _T. kaykai_, _T. deion, T. pretiosum,_ and _T. atopovirilia_; however, limitations to transmission exist. _In vitro_ successful horizontal transfer is uncommon within _Trichogramma_, which suggests that the density of _Wolbachia_ must be relatively high inside of the hosts' ovaries. Cytoplasmic incompatibility of the host and bacterium can also be the source of this unsuccessful transfer in-vitro. These limitations _in vitro_ suggest that in nature, horizontal transfer by parthenogenesis-inducing _Wolbachia_ may be a difficult and rare phenomenon. However, when looking at the _Wolbachia_-host associations, the _Trichogramma-Wolbachia_ form a monophyletic group based on several _Wolbachia_-specific genes, which may be explained by horizontal transfer of _Wolbachia_ between different species. Therefore, although interspecific horizontal transfer of _Wolbachia_ is limited _in vitro_, it is likely to occur quite frequently in nature and is not well understood yet.

The effects of _Wolbachia_ in _Trichogramma_ have several evolutionary implications. Commonly, uninfected wasps are unable to breed with infected wasps. Many generations of reproductive isolation of these different groups may result in speciation. In addition, some hosts can evolve with a dependency on _Wolbachia_ for core reproductive functions, such as 卵子生成，so that eventually an infection is a requirement for successful reproduction. Finally, _Wolbachia_ can influence gender determination in its hosts so that more females are successfully born. This results in a reversal in 性選擇，where females must compete for male mates, which has evolutionary implications as it exposes different phenotypes to natural selection.

## Biological control

_Trichogramma_ spp. have been used for control of lepidopteran pests for many years. They can be considered the _Drosophila_ of the parasitoid world, as they have been used for inundative releases and much understanding today comes from experiments with these wasps.

Entomologists in the early 1900s began to rear _Trichogramma_ spp. for biological control. _T. minutum_ is one of the most commonly found species in Europe and was first mass reared in 1926 on eggs of _Sitotroga cerealella_. _T. minutum_ has been investigated as a method of biological control of the _Choristoneura fumiferana_, a major pest of spruce and fir forests.

Nine species of _Trichogramma_ are produced commercially in insectaries around the world, with 30 countries releasing them. _Trichogramma_ wasps are used for control on numerous crops and plants; these include cotton, sugarcane, vegetables, sugarbeets, orchards, and forests. Some of the pests controlled include cotton bollworm (_Helicoverpa armigera_), codling moth (_Cydia pomonella_), lightbrown apple moth (_Epiphyas postvittana_), and European corn borer (_Ostrinia nubilalis_).

_Trichogramma_ species vary in their host specificity. This can lead to nontarget hosts being parasitized. This, in turn, can cause problems by reducing the amount of parasitism of the target host, and depending on the rate of parasitism, nontarget effects could be significant on nontarget host populations. Research is being done on the use of _Trichogramma_ wasps to control populations of spruce bud moth (_Zeiraphera canadensis)_, which damages white spruce trees.

### Species used

The most commonly used species for biological control are _T. atopovirilia_, _T. brevicapillum_, _T. deion_, _T. exiguum_, _T. fuentesi_, _T. minutum_, _T. nubilale_, _T. platneri_, _T. pretiosum_, and _T. thalense_.

## _T. pretiosum_

_T. pretiosum_ is the most widely distributed species in North America. It is a more generalized parasitoid, able to parasitise a range of different species. It has been the focus of many research studies and has been successfully reared on 18 genera of Lepidoptera. _T. pretiosum_ was introduced into Australia in the 1970s as part of the Ord River Irrigation Area IPM scheme.

## _T. carverae_

_Trichogramma carverae_ is mainly used for light brown apple moth and codling moth control, and is predominately used in orchards. In Australia, _T. carverae_ is used for biological control of light brown apple moth in vineyards. Though Australia has its own native _Trichogramma_ species, not much work has been undertaken to use them commercially for biological control within Australia.

Light brown apple moth is common throughout Australia and is polyphagous on more than 80 native and introduced species. The larvae cause the most damage, especially to grape berries, as their feeding provides sites for bunch rot to occur. Losses in the crops can amount up to $2000/ha in one season. It is very predominant in areas such as the 雅拉河谷. Insecticide use is not a choice method for most growers, who prefer a more natural means of controlling pests. As a result, _Trichogramma_ wasps were considered a good candidate for biological control, even more so as the moth larvae are difficult to control with insecticide. Moreover, light brown apple moths are relatively vulnerable to egg parasitism, with their eggs being laid in masses of 20-50 on the upper surfaces of basal leaves in grapevines.

## 部分物種

以下譯名參照龐飛雄及陳泰魯 (1974) 使用的名稱:441：

* _Trichogramma aomoriense_
* _Trichogramma atopovirilia_
* 澳洲赤眼蜂 _Trichogramma australicum_ Giraulf：見於中國:441。
* _Trichogramma brassicae_
* _Trichogramma brevicapillum_
* _Trichogramma carverae_
* 螟黃赤眼蜂 _Trichogramma chilonis_:442
* 舟蛾赤眼蜂 _Trichogramma closterae_ Pang & Chen 1974：見於中國:441
* _Trichogramma deion_
* 松毛蟲赤眼蜂 _Trichogramma dendrolimi_ Matsumura：見於中國:441。
* 食胚赤眼蜂 _Trichogramma embryophagum_ (Hartig):441
* 暗黑赤眼蜂 _Trichogramma euproctidis_ (Giraut)：見於中國:441。
* 廣赤眼蜂 _Trichogramma evanescens_ Westwood, 1833：見於中國:441。
* _Trichogramma exiguum_
* _Trichogramma falx_
* 暗褐赤眼蜂 _Trichogramma fasciatum_ (Perkins):442
* _Trichogramma fuentesi_
* _Trichogramma funiculatum_
* 稻螟赤眼蜂 _Trichogramma japonicum_ Ashmead：見於中國:441。
* _Trichogramma jezoensis_:442
* _Trichogramma koehleri_ Blanchard:442
* 粘蟲赤眼蜂 _Trichogramma leucaniae_ Pang & Chen, 1974:441
* _Trichogramma luteum_:442
* 舌突赤眼蜂 _Trichogramma lingulatum_ Pang & Chen, 1974:441
* 毛利赤眼鋒 _Trichogramma maori_
* 微小赤眼鋒 _Trichogramma minutum_ Riley:442
* _Trichogramma nubilale_
* 玉米螟赤眼蜂 _Trichogramma ostriniae_ Pang & Chen, 1974
* _Trichogramma papilonis_
* _Trichogramma platneri_
* _Trichogramma pretiosum_
* 微突赤眼蜂 _Trichogramma raoi_ Nagaraja：見於中國:441。
* 窄突赤眼蜂 _Trichogramma retorridum_ (Giraulf):442
* 顯棒赤眼蜂 _Trichogramma semblidis_ (Aur.):441
* 疏毛赤眼蜂 _Trichogramma semifumatum_ (Perkins):442
* 鳳蝶赤眼蜂 _Trichogramma sericini_ Pang & Chen 1974：見於中國:441。
* _Trichogramma siddiqi_
* _Trichogramma thalense_
* _Trichogramma valentinei_
* _Trichogramma vitripenne_ Walker:442
* _Trichogramma yawarae_

## 參考文獻

## 外部連結

* 維基物種上的相關資訊：赤眼蜂屬
* Biocontrol-oriented _Trichogramma_ Manual
* _Trichogramma_ Article
* Trichogramma dropping by drones （頁面存檔備份，存於網際網路檔案館）