Effect of patch size of the exotic host plant Calotropis procera (Apocynaceae) on herbivory

Abstract

Calotropis procera is a xerophytic perennial milkweed shrub native to Asia and Africa, which currently is also widely distributed throughout the Brazilian Caatinga. C. procera is well defended against herbivores, especially with latex and toxic steroidal cardenolides. The goal of this study was to evaluate how patch size of this exotic host plant affect insect herbivory. Eight patches were selected containing a varied number of C. procera individuals (5, 8, 29, 31, 55, 79, 116, and 172 individuals/patch) in the Caatinga. Patches were divided into four categories according to the number of C. procera individuals: very small (5 and 8), small (29 and 31), intermediate (55 and 79), and large (116 and 172). The percentage of herbivory was greater in patch categories with more individuals. Among the herbivorous insects associated with C. procera, larvae of Danaus spp. (Lepidoptera: Nymphalidae) were commonly observed feeding on all patches. These herbivores present specialized behaviors to circumvent the presence of latex on the host leaves. Adult Danaus spp. females probably had higher probability to find large patches of C. procera, leaving a greater abundance of eggs and, consequently, increasing the herbivory by their larvae in these patches. In contrast to immigration tendency, emigration from large patches may be lower, because there is a higher probability of finding resources (e. g. suitable C. procera leaves) inside large patches compared with small patches. We conclude that patch size of the host plant C. procera is a major factor affecting herbivory.

Localização Remota, Classificação e Identificação das Erosões no Cinturão Verde de Ilha Solteira

“…Sclerophylly is among the selective mechanisms for plant adjustment in xeric habitats (TURNER, 1994;LUCAS et al, 2000;GONÇALVES-ALVIM et al, 2004. Moreover, It is argued that sclerophylly can act as a physical defense against herbivory, or as a mechanism for nutrient conservation and protection of leaf longevity (FERNANDES, 1994;GONÇALVES-ALVIM et al, 2006;SILVA et al, 2009;. Thus, leaves in xeric habitats are expected to be smaller, thicker and unpalatable to herbivores than leaves in mesic habitats (FERNANDES, 1994;BOEGER;WISNIEWSKI, 2003;FACCION et al, 2021).…”

Estudos populacionais de Urbanus esta Evans 1952 (Hesperiidae, Lepidoptera) em Desmodium uncinatum (Jacq.) DC. (Fabaceae) e seus inimigos naturais, na Serra do Japi, Jundiaí - SP

“…A quantidade de tricomas não diferiu entre ambientes nas categorias foliares, diferindo Tricomas representam atributos morfológicos da planta que podem impor restrições a insetos herbívoros (LEVIN 1973, JOHNSON 1975, FERNANDES 1994, MEDEIROS et al 2004, MEDEIROS & BOLIGON 2007, CARDOSO 2008, FORDYCE & AGRAWAL 2001 1978). No entanto, insetos tropicais podem ter variações em seus tamanhos populacionais, influenciadas tanto pelas flutuações na temperatura e precipitação quanto por inimigos naturais.…”