Biorational Control of Pests: Parasitoid Insects and Their Characteristics

Biorational Control of Pests: Parasitoid Insects and Their Characteristics

With the mission of being the best allies during your work in the field, in Seminis, we share valuable agronomic advice that will help you take your crops to the next level. Following the management information that we reviewed in the last article, in this week’s blog, we continue to learn about beneficial insects for agricultural fields used as bio-rational pest control, specifically the so-called “Parasitoids.”

A parasitoid is an organism that lives and feeds on a host being, being able to develop inside or outside it. Normally only the immature stage of these insects consumes and destroys pests, but there are also some types of adult wasps that usually hunt insects that damage crops, which contributes to agricultural control. As a clarification, the difference between a parasitoid and a parasite is that the former does kill its host, while the latter feeds and then leaves its prey. Examples of this are the different types of bedbugs and fleas.

Most parasitoids in agricultural fields are flies and wasps, of the Diptera and Hymenoptera orders, respectively. The most numerous are wasps, of which there are a large number of families that attack a wide variety of pests, from aphids and eggs to adult insects. It is important to note that the vast majority of these beneficial wasps do not have the ability to bite humans or harm them in any way.

Next, in the hands of the National Institute of Forestry, Agricultural and Livestock Research (INIFAP), we present a list of some of the most important parasitoids for agriculture in Mexico:

Diaeretiella rapae

It belongs to the Aphidiidae family and is one of the most commonly used parasitoids in the Americas, massively raised primarily as a biological control against aphid and aphid pests.

The female parasitic nymphs, with less preference for adults, depositing a developing egg in the host, form a pupa and then emerges as an adult to repeat the life cycle. Only one larva develops in each host, which, when it dies, leaves its mummified and brown exoskeleton. A female has the ability to parasitize more than 500 aphids.

It comprises at least 68 genera and numerous species. This parasitoid of the Campopleginae family normally deposits its eggs in the larvae of Lepidoptera and sometimes in insects of the order Coleoptera. The larvae, which develop individually, cause the host to stop eating three days after being parasitized, dying a day later. At the end of its development, the larva emerges and forms a cocoon to continue its life cycle.

Worldwide it is distributed throughout the Americas. In Mexico, it is found more in the states of Michoacán, Colima, and Jalisco.

Archytas marmoratus

From the Tachinidae family, that is, flies of different types, this insect is distinguished from other flies due to its more robust body and thick bristles that cover it.

This parasitoid specializes in attacking Lepidoptera larvae by locating them through their feces. When he finds them, he fixes his eggs directly on the host’s body or on the leaves of the plants where he lives. The parasitic larva feeds on the host until it enters its pupal phase when it dies; then, the parasitoid continues its life cycle.

Prisoners spinator

The larvae of Lepidoptera and Coleoptera are the main prey of this insect belonging to the Cremastinae subfamily, which in Mexico can easily be found in the state of Michoacán.

The female of this ovipositing wasp inside the host larva, a single egg, which emerges when the host has died reaching its prepupa or pupa state. Once out of the guest, he immediately creates a cocoon in which he continues his path to adulthood.

Trichogramma pretiosum

Around the world, this insect is used commercially in 32 million hectares of agricultural land in more than 50 countries. It also has a history as bio-rational control in our country: for 50 years, its reproduction and liberation in the fields have been one of the most important, having been implemented in approximately 34 thousand hectares in the first decade of the 21st century.

In Mexico, 28 species of the genus Trichogramma are registered, of which T. pretiosum is one of the most valuable because it attacks species of several pests of economic importance, especially of the order Lepidoptera.

Unlike the other insects that we have indicated, this tiny wasp deposits its eggs in those of its prey. The female is able to parasitize several eggs during her active life, and in each of them, up to three Trichogramma parasitoids develop, depending on the host. Generally, adult wasps emerge from the eggs, which fly to continue the reproduction cycle.

We hope this information will be useful for you to continue investigating this type of pest management, which, in addition to resulting in an economic advantage for farmers, is an excellent way to contribute to caring for the environment. Thanks for reading us one more time! In the following article, we will continue with a list of predatory insects used as irrational control of pests.

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