ABSTRACT: Callosobruchus maculatus (Fab.) (Coleoptera: Chrysomelidae: Bruchinae) is the main pest of Vigna unguiculata (L.) Walp. during the grain storage period. This study aimed to report the occurrence of a natural enemy associated with C. maculatus in cowpea, in the semiarid region of the Rio Grande do Norte state, Brazil. For this, cowpea samples were collected and placed in closed plastic containers, where they remained until the emergence of adult insects. From the infested samples, adults of C. maculatus and of the Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae: Pteromalinae) parasitoid emerged. This is the first report of D. basalis parasitizing C. maculatus in the semiarid region of the Rio Grande do Norte state.

KEYWORDS: Cowpea, Bruchinae, Pteromalidae, biological control.

RESUMO: Callosobruchus maculatus (Fab.) (Coleoptera: Chrysomelidae: Bruchinae) é a principal praga de Vigna unguiculata (L.) Walp. durante o período de armazenamento dos grãos. Objetivou-se relatar a ocorrência de um inimigo natural associado a C. maculatus em feijão-caupi, na região semiárida do Rio Grande do Norte, Brasil. Para isso, amostras de feijão-caupi foram coletadas e colocadas em recipientes plásticos fechados, onde permaneceram até a emergência dos insetos adultos. Das amostras infestadas, emergiram adultos de C. maculatus e do parasitoide Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae: Pteromalinae). Este é o primeiro relato de D. basalis parasitando C. maculatus na região semiárida do Rio Grande do Norte.

PALAVRAS-CHAVE: Feijão-caupi, Bruchinae, Pteromalidae, controle biológico.

Carátula del artículo

Scientific Note

Occurrence of Dinarmus basalis parasitizing Callosobruchus maculatus in Vigna unguiculata in the semiarid region of the Rio Grande do Norte state, Brazil

Ocorrência de Dinarmus basalis parasitando Callosobruchus maculatus em Vigna unguiculata no semiárido do Rio Grande do Norte, Brasil

Ewerton Marinho da Costa ewerton.marinho@professor.ufcg.edu.br

Universidade Federal de Campina Grande, Brasil

Francisco Edivino Lopes da Silva edivino_ufersa@hotmail.com

Bayer, Brasil

Elania Clementino Fernandes elaniacf@gmail.com

Universidade Federal Rural do Semiárido, Brasil

Valmir Antonio Costa valmir@biologico.sp.gov.br

Instituto Biológico, Brasil

Elton Lucio Araujo elton@ufersa.edu.br

Universidade Federal Rural do Semiárido, Brasil

Pesquisa Agropecuária Tropical, vol. 53, e75902, 2023
Escola de Agronomia/UFG

Received: 17 April 2023

Accepted: 19 July 2023

Published: 16 August 2023

DOI: https://doi.org/10.1590/1983-40632023v5375902

Callosobruchus maculatus (Fab.) (Coleoptera: Chrysomelidae: Bruchinae) is the main pest of Vigna unguiculata (L.) Walp. cowpea during the grain storage period (Heidari et al. 2016, Medeiros et al. 2017, Silva et al. 2020). The damage related to the attack of this pest is due to the penetration and feeding of the larvae inside the grains, affecting their commercial and agronomic quality and making them unsuitable for human consumption and sowing (Oliveira et al. 2014).

The main method to control C. maculatus is chemical control with synthetic insecticides (e.g., organophosphates, pyrethroids and phosphine) (Gusmão et al. 2013). In Brazil, the number of insecticides registered for the control of C. maculatus in cowpea is limited, being restricted to magnesium phosphide (Brasil 2003). However, the inappropriate use of these insecticides can cause several problems, e.g., intoxication of rural workers, residue accumulation in grains and emergence of resistant pest populations, among others (Pimentel et al. 2010, Hedjal-Chehheb et al. 2013).

Thus, the use of botanical insecticides (Hedjal-Chehheb et al. 2013, Izakmehri et al. 2013, Mbata & Payton 2013, Sousa Neto et al. 2019) and biological control with parasitoids (Amevoin et al. 2007) have been studied as alternatives to synthetic insecticides. Several parasitoids associated with C. maculatus have been reported worldwide, with the Pteromalidae family being the most diversified, with five species distributed in the genera Dinarmus, Theocolax and Lariophagus (Van Huis 1991). In a study carried out in west Africa, Amevoin et al. (2007) reported that, after the parasitoid Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae) was released, a significant reduction in the populations of C. maculatus in stored cowpea was observed, consequently resulting in lower losses, when compared to the control treatment.

In Brazil, information about the occurrence of natural enemies of the Callosobruchus genus is still scarce, with records in the states of Santa Catarina (Lima 1942), Pará (Ohashi et al. 1993) and São Paulo (Costa et al. 2007). Therefore, this study aimed to report, for the first time, the occurrence of a parasitoid associated with C. maculatus in cowpea, in the semiarid region of the Rio Grande do Norte state, Brazil.

A total of 20 cowpea samples of 200 g from the Mossoró region (5º11’S and 37º20’W) were taken to the laboratory at the Universidade Federal Rural do Semiárido, in 2013, where they were placed in plastic containers (6 cm high × 10 cm in diameter) closed at the top with voile fabric and kept in an air-conditioned room (25 ± 2 ºC; 70 ± 10 % RH; 12-h photoperiod). The cowpea samples were inspected daily until the emergence of C. maculatus adults (± 20 days after collection) or parasitoids. Subsequently, the obtained insects were transferred to containers with 70 % ethyl alcohol and duly labelled (date and sampling location). The emerged parasitoids were identified according to Bouček & Heydon (1997) for genus and Rasplus (1989) for species. The Bruchinae specimens were sent to the Universidade Federal Rural de Pernambuco (UFRPE), in Recife, Pernambuco state, Brazil, for identification. The voucher specimens of the parasitoid were deposited in the entomological collection of the Instituto Biológico of São Paulo, whereas the C. maculatus specimens were deposited in the entomological collection of the UFRPE.

A total of 2,083 insects were collected from the cowpea samples, with 1,414 C. maculatus and 669 parasitoids belonging to Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae) (Figure 1). This parasitoid is a solitary idiobiont ectoparasitoid of immature insects and may be used for the biological control of C. maculatus (Amevoin et al. 2007). This parasitoid is the main natural enemy of bruchids in cowpea grains (Sanon et al. 2011). Dinarmus basalis is originally from Africa and has dispersed throughout the Americas, Asia and Europe due to the trade in grains and seeds (Rasplus 1989).

Figure 1
Female of Dinarmus basalis (Rondani) (Hymenoptera: Pteromalidae) collected in Mossoró, Rio Grande do Norte state, Brazil.

In Brazil, D. basalis has already been reported parasitizing Callosobruchus chinensis (L.) associated with Vigna radiata (L.) in the Santa Catarina state (Lima 1942), Acanthoscelides obtectus (Say) in the Northeast region of Brazil (Oliveira 1948), C. maculatus associated with V unguiculata in the Pará state (Ohashi et al. 1993) and Callosobruchus analis (F.) associated with Glycine max (L.) in the São Paulo state (Costa et al. 2007). However, this is the first report of D. basalis parasitizing C. maculatus associated with cowpea in the semiarid region of the Rio Grande do Norte state, Brazil.