Infestation of the invasive exotic moth Hyblaea puera (Lepidoptera: Hyblaeidae) in Avicennia L. (Acanthaceae) in the mangrove of the Mamanguape River, Paraíba, Brazil

Highlights

• Hyblaea puera caterpillars simultaneously infested Avicennia germinans and Avicennia schaueriana trees.

• During the caterpillar outbreak period, the foliar herbivory rate was > 50 %.

• The caterpillar infestation was higher in Avicennia germinans.

Abstract

Outbreaks of caterpillars have been recorded in some mangrove forests in Brazil and other countries. This study reports an infestation of Hyblaea puera caterpillars (Cramer, 1777) (Lepidoptera: Hyblaeidae) in the mangrove forest of the Mamanguape River, Paraíba State, Brazil. The attacks occurred between May and July 2020 and affected Avicennia germinans (L.) L. and Avicennia schaueriana Stapf & Leechm. ex Moldenke. During the caterpillar outbreak period, the foliar herbivory rate was > 50 % in both species. Throughout the distribution area of the species in the estuary, there was variation in the intensity of caterpillar infestation: from the absence of attack to the complete defoliation of the trees in mono-specific forests of A. germinans. The consequences of severe defoliation are briefly discussed, emphasizing mangrove conservation.

Introduction

The ecological role played by herbivores in mangrove forests involves the consumption of plant material, affecting the performance of the plant and the functioning of the ecosystem (Cannicci et al., 2008). Although they cause damage at the individual level, the activities of herbivores can be seen as a positive impact in the mangrove forest, influencing, for example, the transfer of energy in the ecosystem (Fernandes et al., 2009).

In general, leaf consumption caused by herbivory corresponds to less than 10 % in mangrove species (Farnsworth and Ellison, 1991; Romero et al., 2006; Alongi, 2009; Silva et al., 2015). However, high levels of defoliation attributed to insects have been reported in some mangroves (Anderson and Lee, 1995; McKillup and McKillup, 1997; Elster et al., 1999; Saur et al., 1999; Duke, 2002; Mehlig and Menezes, 2005; Jenoh et al., 2016; Faraco et al., 2019; Biswas et al., 2018). Lepidopteran caterpillars have been indicated as the principal agents responsible for severe defoliation in mangrove forests. For example, an infestation of caterpillars of Nephopterix syntaracti Turner (Lepidoptera: Pyralida) in Avicennia marina (Forsk.) Vierh. has been registered in a mangrove in Hong Kong (Anderson and Lee, 1995). Saur et al. (1999) documented intense leaf consumption in Avicennia germinans (L.) L. trees by caterpillars of Hyblaea puera (Cramer, 1777) (Lepidoptera: Hyblaeidae) and Junonia evarete (Cramer, 1779) (Lepidoptera: Nymphalidae) in Guadeloupe. Avicennia alba Blume has been affected by severe defoliation caused by H. puera in a mangrove in India (Biwas et al., 2018). Other studies have reported caterpillars of this species as pests of A. marina in India (Arun and Mahajan, 2012) and of Avicennia officinalis L. in Bangladesh (Baksha and Crawley, 1998). In Brazil, infestations of H. puera caterpillars have been observed in trees of A. germinans in the states of Pará and Maranhão (Menezes and Mehlig, 2005) and of Avicennia schaueriana Stapf & Leechm. ex Moldenke in the state of Paraná (Faraco et al., 2019), but there have still been no reports of simultaneous caterpillar infestations in the two species of Avicennia in Brazilian mangroves.

The mangrove forest of the Mamanguape River is located along the north coast of the state of Paraíba, Brazil, and is considered one of the most conserved in the state, despite suffering from different forms of degradation, such as installation of shrimp-farms, overexploitation of resources, alteration of water circulation and selective cutting. Local residents reported that infestations of a caterpillar caused severe defoliation of A. germinans in 2011, but the species responsible for the attack was not identified at the time. In 2016 there was a record of intense leaf consumption in A. germinans caused by caterpillars of J. evarete, but without severe defoliation of the trees (personal observation).

This study reports an outbreak of H. puera in trees of A. germinans and A. schaueriana in the mangrove of the Mamanguape River, Paraíba. As far as we know, this is the first record of simultaneous infestation in two mangrove species in Brazil.