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The obligate ectoparasite Rhipicephalus (Boophilus) annulatus, also known as cattle tick, is the hard tick vector of babesiosis, a protozoal infection that causes severe meat production losses at huge economic costs. Although babesiosis was eradicated from the United States, its vector still exists in Mexico and different security measures are used to prevent its reintroduction into the U.S. Furthermore, the massive use of chemical acaricides during the last century has resulted in the development of resistance and toxicological problems. A possible and more sustainable alternative could be represented by the applications of biopesticides. Recently, two sesquiterpenoids, inuloxin A and α-costic acid isolated from Dittrichia viscosa, a perennial native plant of the Mediterranean basin, showed several interesting biological activities including acaricidal and antifeedant activities. Both inuloxin A and α-costic acid caused an impact on the hatch rate of the eggs and a larval mortality rate higher than 80% in vitro bioassays on eggs of R. annulatus. Moreover, the hatch rate of the eggs and the mortality rate of the larvae seem to be dependent on the timing of application of the compounds on the eggs. These results suggested a potential use of both compounds to control R. annulatus.

The fungal pathogens Cochliobolus australiensis and Pyricularia grisea have recently been isolated from diseased leaves of buffelgrass (Cenchrus ciliaris) in its North American range, and their ability to produce phytotoxic metabolites that could potentially be used as natural herbicides against this invasive weed was investigated. Fourteen secondary metabolites obtained from in vitro cultures of these two pathogens were tested by leaf puncture assay on the host plant at different concentrations. Radicinin and (10S, 11S)-epi-pyriculol proved to be the most promising compounds. Thus, their phytotoxic activity was also evaluated on non-host indigenous plants. Radicinin demonstrated high target-specific toxicity on buffelgrass, low toxicity to native plants, and no teratogenic, sub-lethal, or lethal effects on zebrafish (Brachydanio rerio) embryos. It is now under consideration for the development of a target-specific bioherbicide to be used against buffelgrass in natural systems where synthetic herbicides cause excessive damage to native plants.

The organic extract of the aerial parts of Dittrichia viscosa, a perennial native plant of the Mediterranean basin, showed a significant acaricidal activity against Varroa destructor, the parasite mite of Apis mellifera, commonly called honey bee. Among the metabolites isolated from the organic extract of this Asteraceae, α-costic acid showed to be one of the compounds responsible for the toxic activity exhibited by the crude plant extract on this parasite mite species. In addition to the toxic effect a clear acaricidal response has been recorded when the parasitic mite was exposed to 1 mg/mL concentration of α-costic acid while no effects have been showed on honey bees using the same compound at the same concentration. This finding suggests a potential use of α-costic acid to control Varroa mites. The possibility to reliably achieve absolute configuration of α-costic acid by DFT computational analysis of chiroptical spectra has been also demonstrated.†