Parasitism in cotton stainers, Dysdercus spp. (Hemiptera, Pyrrhocoridae).
Dr. J.R. de Almeida
[https://x.com/dralmeidajr][in
Editora Priscila M. S. Gomes
Study in Rio de Janeiro Reveals High Parasitism Rates in Cotton Stainer Bugs
A recent study conducted in Rio de Janeiro State has shed light on the natural enemies attacking cotton stainer bugs of the genus Dysdercus (Hemiptera, Pyrrhocoridae). Researchers monitored two pasture sites with the presence of malvaceous plants, a preferred habitat for these insects, and identified both a wide diversity of Dysdercus species and a remarkable level of parasitism that plays a crucial role in regulating their populations.
At the first site, Dysdercus maurus was the dominant species throughout the entire observation period, although D. fulvoniger, D. ruficollis, and D. mendesi appeared occasionally. At the second site, D. ruficollis and D. maurus were consistently present, while D. obscuratus, D. fernaldi, D. honestus, and other species occurred sporadically. This diversity highlights the strong adaptability of the group to local environmental conditions.
The study also revealed the action of two ectoparasitic mites collected from adult Dysdercus: species of the genus Leptus, responsible for parasitism rates between 5.26% and 11.11%, and Hemipteroseius sabbaticus, which reached far higher levels ranging from 9.76% to an impressive 77.78% at the first site, and from 15.38% to 100% at the second. In addition, the parasitic fly Acaulona brasiliana was recorded, with infestation levels varying from 2.44% to 44.44%.
These findings demonstrate not only the intensity of parasitic pressure on cotton stainer populations but also the importance of natural enemies as regulating agents in ecological dynamics. According to the researchers, understanding parasitism rates and seasonal abundance patterns provides valuable insights into natural biological control mechanisms that may reduce the need for insecticide use in cotton fields and related crops.
The study reinforces the idea that interactions between Dysdercus species and their parasites play a decisive role in maintaining ecosystem balance and may pave the way for sustainable agricultural management strategies, particularly in regions vulnerable to pest infestations.
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