Repipta flavicans (Amyot & Serville, 1843)

Marsaro Júnior, Alberto Luiz, Gil-Santana, Hélcio Reinaldo & Moura, Luciano de A., 2024, Species of Reduviidae (Hemiptera: Heteroptera) associated with a canola crop (Brassica napus L. var. oleifera; Brassicales: Brassicaceae) in Passo Fundo, Rio Grande do Sul, Brazil, Revista Chilena de Entomología (Rev. Chil. Entomol.) 50 (3), pp. 535-548 : 541-544

Repipta flavicans (Amyot & Serville, 1843)

Repipta Stål, 1859 was revised by Martin-Park et al. (2012), with the redescription of its species, including R. flavicans , a somewhat common reduviid in many Neotropical countries. Gaméz-Virués et al. (2003) described the immature stages and life cycle of R. flavicans . The specimens of R. flavicans measure approximately between 10 to 12 mm in length, with wide variation in color ( Martin-Park et al. 2012), although the pronotum hind lobe usually presents a pale longitudinal medial area (HRG-S pers. obs.) ( Fig. 4D ). In this study, this species was observed in the field preying on an adult of Diabrotica limitata (Sahlberg, 1823) ( Coleoptera : Chrysomelidae : Galerucinae : Luperini ). Diabrotica Chevrolat, 1837 encompasses more than 300 species ( Wilcox 1972) of essentially polyphagous beetles, that is, they feed on various families and species of plants ( Jolivet 1987); D. limitata is no different – it feeds on many host plants, several of which are crops.

Distribution. Argentina, Brazil, Bolivia, Costa Rica, Colombia, Cuba, Guatemala, French Guiana, Honduras, Mexico, Nicaragua, Panama, Paraguay and Uruguay ( Martin-Park et al. 2012).

We observed that At. cinereus crassicornis was the most abundant species in the experimental canola plantation studied. It must be, therefore, the leading species contributing to pest control in this context. This species has already been recorded in cotton and rice crops ( Michel 1993; Souza et al. 2015). Hence, the presence of this reduviid in canola shows it can contribute to the pest control of plants cultivated both in the hottest and coldest seasons, as is the case of canola in South Brazil.

The second most abundant species found, C. annulosus , should also be an important predator in canola plantations. Species of this genus are generalist predators, and studies with C. nigroannulatus revealed that this species stood out as a predator of several pests in tobacco plantations ( Jahnke et al. 2002; Marques et al. 2006).

As earlier stated, the canola plantation exhibits a considerable diversity of predaceous true bugs ( Pentatomidae - Asopinae and Reduviidae ) which prey on both beneficial insects (pollinators such as bees) and pests, having a crucial role in the control of the latter. Therefore, it is vital that the plantation management (especially regarding the use of pesticides) is done carefully to cause as little damage as possible to these biological control agents. This would guarantee the preservation of these insects not only in canola plantations, but also in others crops which integrate the diverse agroecosystems found in Brazil.

Taking into account the diversity of species of Reduviidae and their role in the predation of pests in canola crops, and also because there is currently no sufficient scientific knowledge in Neotropics about the biology, behavior and predation efficiency of these true bugs to allow the rearing, augmentation and release in under field conditions, it is extremely important that farmers adopt practices that aim to preserve them in agroecosystems. Among these practices, we can highlight the maintenance of the native vegetation, legal reserves, areas of permanent preservation (“APPs”) and riparian forests. These spots of natural vegetation besides providing shelter and preys to reduviids during agricultural off-season periods, may allow them to remain close to the crops, ensuring their role as biological pest control agents.

As reported, canola plants are visited by a large diversity of arthropods (phytophagous, pollinators and predators) throughout their development. Among the predators, studies have revealed an increasing number of species associated with this plant species, as reported here for true bugs. It is likely that canola plantations house other species of predaceous true bugs still unreported. Thus, further studies are needed to understand more precisely their real diversity associated with canola and how exactly each of these species interact with the other arthropods visiting the plantations.

Furthermore, more studies are needed to understand the population dynamics of reduviids in canola plantations, as well as the biotic and abiotic factors that affect their populations throughout the crop cycle.

In summary, the present work recorded the occurrence of seven species of Reduviidae in a canola crop (with larger abundance of Atrachelus cinereus crassicornis ), expanded the knowledge about the geographic distribution of these species, reported predation of three reduviid species and presented management strategies aimed to the preservation, conservation and maintenance of these predators in agroecosystems.

The results obtained is a contribution to the knowledge about the diversity and ecology of reduviid species that occur in canola crop, including the choosing of preys by them as well as their climatic adaptability taking into account that the species were collected both in cold and warmer months.

On the other hand, in spite of the relevance of the results presented in this study, the small number of samples and short survey period seem not to be enough to express the full diversity of reduviids that may be potentially present in a canola crop. Therefore, more exhaustive surveys are necessary, including larger areas and different cultivation regions, to record which are the most common and abundant species of Reduviidae that live in the canola agrosystem. Furthermore, future studies can investigate the pest predation capacity of reduviid species occurring in canola and which may be useful for biological control programs. In the latter case, possibly for future mass releases of these predators in the field.

Figures

Figures 4A-D. A-B. Harpactor tuberculosus, female preying on a specimen of Astylus (Astylus) quadrilineatus (Coleoptera: Melyridae). C-D. Dorsal view. C. Isocondylus elongatus, male. Scale: 5.0 mm. D. Repipta flavicans, female. Scale: 3.0 mm. / Figuras 4A-D. A-B. Harpactor tuberculosus, hembra depredando un espécimen de Astylus (Astylus) quadrilineatus (Coleoptera: Melyridae). C-D. Vista dorsal. C. Isocondylus elongatus, macho. Escala: 5,0 mm. D. Repipta flavicans, hembra. Escala: 3,0 mm. Discussion