Esperanza García-Pascual

Opuntia ficus-indica has always interacted with many phytophagous insects; two of them are Dactylopius coccus and D. opuntiae. Fine cochineal (D. coccus) is produced to extract carminic acid, and D. opuntiae, or wild cochineal, is an invasive pest of O. ficus-indica in more than 20 countries around the world. Despite the economic and environmental relevance of this cactus, D. opuntiae, and D. coccus, there are few studies that have explored volatile organic compounds (VOCs) derived from the plant–insect interaction. The aim of this work was to determine the VOCs produced by D. coccus and D. opuntiae and to identify different VOCs in cladodes infested by each Dactylopius species. The VOCs (essential oils) were obtained by hydrodistillation and identified by GC-MS. A total of 66 VOCs from both Dactylopius species were identified, and 125 from the Esmeralda and Rojo Pelón cultivars infested by D. coccus and D. opuntiae, respectively, were determined. Differential VOC production due to infestation by each Dactylopius species was also found. Some changes in methyl salicylate, terpenes such as linalool, or the alcohol p-vinylguaiacol were related to Dactylopius feeding on the cladodes of their respective cultivars. Changes in these VOCs and their probable role in plant defense mechanisms should receive more attention because this knowledge could improve D. coccus rearing or its inclusion in breeding programs for D. opuntiae control in regions where it is a key pest of O. ficus-indica.

Opuntia ficus-indica has always interacted with many phytophagous insects at its center of origin; two of them are Dactylopius coccus and D. opuntiae. D. coccus, or true cochineal, is produced to extract carminic acid, and D. opuntiae or wild cochineal is a key invasive pest of O. ficus-indica in more than 20 countries around the world. Despite the economic and environmental relevance of this cactus and, D. opuntiae and D. coccus, there are few studies that have explored volatile organic compounds (VOCs) derived from the plant-insect interaction. The aim of this work was to determine VOCs of D. coccus and D. opuntiae feeding on cultivars suitable for their development and to identify different VOCs in cladodes infested by each Dactylopius species. Volatiles were identified through their essential oils, which were obtained by hydrodistillation. A total of 66 VOCs from both Dactylopius species were identified, and 125 from the Esmeralda and Rojo Pelón cultivars infested by D. coccus and D. opuntiae, respectively, were determined. Differential VOCs production due to infestation by each Dactylopius species was also found. Some changes in methyl salicylate, terpenes such as linalool or the alcohol p-vinylguaiacol were related to Dactylopius feeding on cladodes of their respective cultivars. Changes in these VOCs and their probable role in plant defense mechanisms should receive more attention because this knowledge could improve D. coccus rearing, or to its inclusion in breeding programs for D. opuntiae control in regions where it is a key pest of O. ficus-indica.

The objective of this article is to identify the growth, control tactics, collaboration among authors, and emerging trends in scientific research related to the control strategies of Dactylopius opuntiae Cockerell (Hemiptera: Dactylopiidae) through bibliometric indicators. In order to recover the relevant academic articles on the topic, six referential databases were consulted. The keyword used to retrieve bibliographic information was «Dactylopius opuntiae» in the search fields: title, abstract and keywords. 1 212 bibliographic records were obtained, which were sent to the Zotero software, and subsequently reviewed to discard repeated records unrelated to the topic, obtaining only 99 from 1848 to 2022. These records resulted in four bibliometric indicators using Excel and VOSviewer. The dynamic of scientific production has been more evident during the last seven years. Biological control, through predators and entomopathogens, was the most studied emergent research theme. From 1848 to 2000, only 12 documents of scientific production about D. opuntiae control tactics were found; production has been increasing by a greater proportion from 2016 up to 2022. The most outstanding control tactics were focused on biological control and non-conventional chemical control using various products such as oils, plant extracts, soaps, and detergents. Finally, the most frequently mentioned research topic was «biological control». Among other conclusions, the most researched topics were biological control agents (predators and entomopathogens) and plant resistance, which stood out as the tactic that could be most sustainable.