Colonising aliens: caterpillars (Lepidoptera) feeding on Piper aduncum and P. umbellatum in rainforests of Papua New Guinea

Abstract

Abstract. 1. Caterpillar assemblages feeding on two alien plants, Piper aduncum and P. umbellatum, were studied in lowland rainforest in Papua New Guinea and compared with assemblages from 69 species of native woody hosts, including congeneric P. macropiper.2. Species richness of caterpillars feeding on P. aduncum (29 species per 1500 m^ of foliage) and P. umbellatum (36 species) was higher than the median richness for the 69 native hosts (23 species).3. The probability that a caterpillar species colonised alien Piper increased with its host range from 3% for the species feeding on a single plant family to 92% for the species with host range >10 plant families.4. The assemblage on P. aduncum was dominated by a single species {Herpeto-gramma sp. near licarsisalis, Crambidae), which represented 48% of individuals, and also had a high proportion (iA%) of rare species, collected as single individuals. This community structure was indistinguishable from that of a typical native host. In contrast, the P. umbellatum assemblage was unusual as no species represented >10% of individuals.5. The aggressive invasion by P. aduncum of early successional vegetation is not explained by a competitive advantage due to low herbivore load, as the abundance of caterpillars feeding on it was comparable to that of native pioneer plants.6. The caterpillar assemblage on P. aduncum demonstrated that an assemblage indistinguishable from native assemblages in density, species richness, and dominance structure (but not in host specificity) can originate from the existing species pool in lowland rainforests on a recently established tree species in <50 years.

Volatile Chemical Constituents of Piper aduncum L and Piper gibbilimbum C. DC (Piperaceae) from Papua New Guinea

“…In spite of the toxicity of the chemical constituents found in the leaf extracts of the two species of Piper studied, it is interesting to note that P. aduncum is the highly preferred host for a number of caterpillar species [23]. Such selectivity in the assemblages and feeding preferences of the caterpillar may suggest that the accumulation of the phytochemicals, in particular dill apiole, derived from this species could serve as a chemical defence for the caterpillars to deter excessive predation.…”

“…Interestingly, comparative studies conducted on the feeding habits of caterpillars (Lepidoptera) on two exotic Piper species (P. aduncum and P. umbellatum) with the native host species of PNG indicated a higher preference for the two introduced species [23]. The higher assemblage and feeding preference as well as species diversity on P. aduncum is particularly interesting.…”

First Host Plant Record forThaeides muela(Lepidoptera, Lycaenidae: Theclinae: Eumaeini)

“…The latter possibility can be ruled out by our extensive feeding trials, although even then the possibility still persists that a confirmed trophic association occurs but exceptionally in nature. Novotny et al (2003) densiciliatum and XV, both of which we excluded from our analysis due to their small data sets. The native New Guinean P. macropiper ranked even lower than most of our species (1.684).…”

Maladaptive host choice by an alien leaf miner Phyllonorycter leucographella (Lepidoptera: Gracillariidae) has the potential to limit its invasiveness

“…tact between the novel partners (Brändle et al, 2008;Karolewski et al, 2017, but see Andow & Imura, 1994 and host specifi city (Novotny et al, 2003;Roques et al, 2009;Walczak et al, 2017). The ability of an insect to successfully colonize new hosts is also strongly determined by the plant's physical, chemical, and phenological traits (Coley & Barone, 1996;Loranger et al, 2013;Bogdziewicz et al, 2018).…”