Natural Vs Managed Habitat: Effect Over the Seed-Predator Pachymerus nucleorum and Its Natural Enemies

Abstract

The licuri palm, Syagrus coronata (Martius) Beccari (Arecaceae), is widely distributed throughout the Brazilian Caatinga and has high cultural, socioeconomical, and ecological importance. The palm tree logging is prohibited by the Brazilian law, and thus isolated individuals are a common sight on managed pastures in the Brazilian semi-arid region. We aimed to compare the insect seed-predator Pachymerus nucleorum (Fabricius) (Bruchinae) abundance and its predation levels on S. coronata seeds between managed (pasture) and natural (Caatinga vegetation) habitats. We also monitored the parasitoid Heterospilus prosopodis (Viereck) (Braconidae) abundance and other P. nucleorum potential natural enemies (generalist predators and microhymenopterans). We tested the hypothesis that more complex and heterogenous habitats (i.e., with higher plant diversity) support higher abundance of potential P. nucleorum natural enemies. For such, we collected 600 fruits from each habitat and evaluated the seed predation level by P. nucleorum, as well as the P. nucleorum parasitism by H. prosopodis. The P. nucleorum abundance and its potential natural enemies were estimated using 122 sticky traps placed on the S. coronata individuals' crown. Neither the P. nucleorum and generalist predators abundance differed between habitats, whereas the H. prosopodis and microhymenopterans abundance was higher in the natural habitat. Consequently, P. nucleorum parasitism levels by H. prosopodis were also higher in the natural habitat. Our study indicated that habitat with higher plant diversity supported more natural enemies, thus confirming that increased habitat homogenization leads to decreased parasitism levels by the less parasitoids number in managed habitats. Our results may subsidize conservationist management practices in the managed habitats aiming to improve fruit exploitation techniques sustainability and land-use practices, which would thereafter allow for the S. coronata population conservation in the Brazilian Caatinga.

Intraspecific interference between native parasitoids modified by a non‐native parasitoid and its consequence on population dynamics

“…For example, the density of C. chinensis is approximately 1.1 larvae per infested seed under natural conditions (Shinoda & Yoshida, 1985), and the infestation rate usually ranges from 4-8% (Tuda et al, 2004) to 14% (Shinoda & Yoshida, 1985;Shinoda et al, 1992). Also, parasitism rates by A. calandrae and H. prosopidis can be as low as about 15% (Ngamo et al, 2007) and 11% (Silva et al, 2020), respectively. However, in closed storage, densities of stored product pests become extremely high and locally attract numerous A. calandrae by kairomones (Onodera et al, 2002).…”

Direct seeding as a recruitment alternative for the threatened tropical palm Syagrus coronata (Mart.) Beccari in Brazilian dry forest

“…It is an important Non-Timber Forest Product (Lima et al, 2020). It plays a vital role in the income of traditional populations and small farmers (Campos et al, 2019;Silva et al, 2020;Pereira et al, 2021). It is commonly used for the provision of fodder, food, fibers, oils and medicinal products (Campos et al, 2019).…”

Record of tritrophic relationship between Syagrus coronata (Martius) Beccari (Arecaceae), Pachymerus nucleorum Fabricius (Coleoptera: Chrysomelidae: Bruchinae) and Heterospilus sp. (Hymenoptera: Braconidae) in the State of Alagoas, northeastern Brazil

“…No more insect species were found in or out the fruits. Both insects were identified with the help of studies available in the corresponding scientific literature (JohnSon et al 1995;coSta-neto 2004;ramoS-elorDuy et al 2006;cortinoz 2011;anDraDe et al 2013;maia 2013;benton 2015;barboSa 2016;Silva et al 2019). Voucher specimens were deposited at the Insect Bioecology Laboratory's entomological collection in the "Universidade Federal de Alagoas" Biological and Health Sciences Institute.…”

“…There are several records of Pachymerus feeding on seeds of Syagrus sp., but only P. nucleorum and Pachymerus thoracicus Prevett has reliable record preying seeds of S. coronata (anDraDe et al 2013;maia 2013;benton 2015;De meDeiroS et al 2019;Silva et al 2019). These two species can be distingued by the prothorax: Pachymerus thoracicus has a strongly transverse prothorax when compare with other species of Pachymerus (Prevett 1966).…”