A Continuing Battle between Toxins and Insects

Dear Colleagues,

Interspecific relationships are occurring along trophic chains and in competitive or mutualistic interactions, and a common feature to those interactions is that biochemicals substances are usually involved. The tremendous diversity of the insect class offers multiple representations of these varieties of chemical relationships. Therefore, this issue will especially focus on the so-called toxins involved in the relationships of insects with other organisms, with emphasis on insects’ toxins and their effects on target species.

Insects may encounter many toxins in their surrounding environment and can be especially affected by these toxins produced by other organisms, competitors, predators or parasites. Entomopathogens and plants produced insecticidal substances targeting more or less specifically different insect physiological functions such as the digestive, neuronal, muscular and immune systems. As a response, many insects have developed defense or resistance strategies allowing them to escape or inhibit the effects of toxic substances that have been either swallowed through diet or transmitted/injected by predators or parasites. Other insects may accumulate neutralized plant toxins in their own tissues, therefore developing a deterring effect towards predators. Also, for now about a century, many insect species listed as pests towards human or its cattle (insect vectors of pathogens), or phytophagous insect pests, have been sprayed by different organic or inorganic insecticides, some of them triggering a physiological response of resistance.

In parallel, insects produce their own toxins for protection and defense against competitors and predators. Insect toxins chemically range between small molecules (polyamines) to polypeptides (proteins) and various physiological functions can be targeted and rapidly affected, in particular nervous systems and neuromuscular ion channels in animals, in the meanwhile, diverse signaling pathways may be triggered in plants. Other toxins can have different modes of action and specifically attack certain organs, tissues or cells, like for example the defense immune system of the target organism. 

These toxins are commonly produced by specifically dedicated glandular systems such as salivary glands of heteropteran, dipteran and coleopteran. Also, hymenopteran females can produce toxins associated with their reproduction apparatus and usually released from venom glands and even ovaries. As a defense against endophagous parasites, toxins can also be secreted by insects in their own hemolymph. Consequently, to such a diversity of functions and targets, insect toxins can be produced by various stages -from larval to imago- of their development.

The arm races that take place between insects and other organisms through toxins production represent a huge field of research and knowledge that would be almost impossible to be exhaustively covered. Therefore, this special issue entitled “A CONTINUING BATTLE BETWEEN TOXINS AND INSECTS” aims at synthesizing major key topics of interspecific relationships occurring through toxins without exhausting the subject. For instance, toxins produced by insects can be considered an almost inexhaustible source of biomolecules of interest, as well as those observed in other organisms of the animal kingdom such as arachnids and reptiles, with applications in different fields and particularly in therapy. We are expecting that this special issue will be inspiring and of great stimulation for pursuing in toxin research.

This issue will focus on several major topics:

• Plants insecticidal substances: nature, function and effects.
• Entomopathogen toxins: nature and effects on insects.
• Storage and neutralization of plant toxins after consumption by insects.
• Insect detoxification of toxins from pesticides.
• Nature and functions of toxins produced by insects.
• Attack strategies developed by insects producing toxins.
• Defense strategies developed by insects producing toxins
• Insect responses against toxins of other organisms.

Dr. Anas Cherqui
Prof. Dr. Geneviève Prévost
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a double-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Toxins is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• insecticidal toxins
• insect toxins
• proteinic, non-proteinic substances
• attack, defense, resistance
• insects’ salivary glands, ovarian fluid and venom.