Charles L. Staines

Tropical Plant–Herbivore Networks: Reconstructing Species Interactions Using DNA Barcodes

Plants and their associated insect herbivores, represent more than 50% of all known species on earth. The first step in understanding the mechanisms generating and maintaining this important component of biodiversity is to identify plant-herbivore associations. In this study we determined insect-host plant associations for an entire guild of insect herbivores using plant DNA extracted from insect gut contents. Over two years, in a tropical rain forest in Costa Rica (La Selva Biological Station), we recorded the full diet breadth of rolled-leaf beetles, a group of herbivores that feed on plants in the order Zingiberales. Field observations were used to determine the accuracy of diet identifications using a three-locus DNA barcode (rbcL, trnH-psbA and ITS2). Using extraction techniques for ancient DNA, we obtained high-quality sequences for two of these loci from gut contents (rbcL and ITS2). Sequences were then compared to a comprehensive DNA barcode library of the Zingiberales. The rbcL locus identified host plants to family (success/sequence = 58.8%) and genus (success/sequence = 47%). For all Zingiberales except Heliconiaceae, ITS2 successfully identified host plants to genus (success/sequence = 67.1%) and species (success/sequence = 61.6%). Kindt’s sampling estimates suggest that by collecting ca. four individuals representing each plant-herbivore interaction, 99% of all host associations included in this study can be identified to genus. For plants that amplified ITS2, 99% of the hosts can be identified to species after collecting at least four individuals representing each interaction. Our study demonstrates that host plant identifications at the species-level using DNA barcodes are feasible, cost-effective, and reliable, and that reconstructing plant-herbivore networks with these methods will become the standard for a detailed understanding of these interactions.

Limited tolerance by insects to high temperatures across tropical elevational gradients and the implications of global warming for extinction

Significance Tolerance to high temperatures will determine the survival of animal species under projected global warming. Surprisingly little research has been conducted to elucidate how this trait changes in organisms living at different elevations of similar latitudes, especially in the tropics. DNA barcodes demonstrate that insect species previously thought to have broad elevational distributions and phenotypically plastic thermal tolerances actually comprise cryptic species complexes. These cryptic species occupy discrete elevational ranges, and their thermal tolerances seem to be locally adapted to temperatures in their life zones. The combination of high species endemism and local adaptation to temperature regimes may increase the extinction risk of high-elevation insects in a warming world. The critical thermal maximum (CTmax), the temperature at which motor control is lost in animals, has the potential to determine if species will tolerate global warming. For insects, tolerance to high temperatures decreases with latitude, suggesting that similar patterns may exist along elevational gradients as well. This study explored how CTmax varies among species and populations of a group of diverse tropical insect herbivores, the rolled-leaf beetles, across both broad and narrow elevational gradients. Data from 6,948 field observations and 8,700 museum specimens were used to map the elevational distributions of rolled-leaf beetles on two mountains in Costa Rica. CTmax was determined for 1,252 individual beetles representing all populations across the gradients. Initial morphological identifications suggested a total of 26 species with populations at different elevations displaying contrasting upper thermal limits. However, compared with morphological identifications, DNA barcodes (cytochrome oxidase I) revealed significant cryptic species diversity. DNA barcodes identified 42 species and haplotypes across 11 species complexes. These 42 species displayed much narrower elevational distributions and values of CTmax than the 26 morphologically defined species. In general, species found at middle elevations and on mountaintops are less tolerant to high temperatures than species restricted to lowland habitats. Species with broad elevational distributions display high CTmax throughout their ranges. We found no significant phylogenetic signal in CTmax, geography, or elevational range. The narrow variance in CTmax values for most rolled-leaf beetles, especially high-elevation species, suggests that the risk of extinction of insects may be substantial under some projected rates of global warming.

HERBIVORY IN GINGERS FROM LATEST CRETACEOUS TO PRESENT: IS THE ICHNOGENUS CEPHALOLEICHNITES (HISPINAE, COLEOPTERA) A ROLLED-LEAF BEETLE?

TI Ssuggested that rolled-leaf hispine beetles (Hispinae, Coleoptera) and plants from the order Zingiberales maintained a highly specialized plant-herbivore interaction for 60 My. The evidence supporting this old and conservative interaction are herbivory marks found on leaves of the genus Zingiberopsis (Zingiberaceae) from the latest Cretaceous and early Eocene. This fossil herbivory was described as the ichnotaxon Cephaloleichnites strongii (Hispinae, Coleoptera), based on the assumption that this type of herbivory can be solely attributed to extant rolledleaf beetles. This ichnotaxon has been a key element in several analyses on the origin, radiation and diversification of tropical insect herbivores. In this paper we report feeding patterns equivalent to those described in Zingiberopsis fossils but produced by larvae of Pyralidae and Choreutidae (Lepidoptera) and Anopsilus weevils (Curculionidae, Coleoptera) in four families of extant Zingiberales. We discuss the implications of C. strongii not being a rolled leaf beetle and how this may affect the current knowledge of the co-diversification of rolled-leaf beetles and their host plants from the order Zingiberales.

The genus Cephaloleia Chevrolat, 1836 (Coleoptera, Chrysomelidae, Cassidinae)

Abstract The species of the Neotropical genus Cephaloleia Chevrolat, 1836 are revised. We present a key to the known larvae of Cephaloleia (8 species), a key to the 95 species known to occur in Mexico, Central America and the West Indies, and a key to the 138 species known to occur in South America. All identification keys were translated to Spanish. Descriptions for the 214 known species of Cephaloleia as well as illustrations for 212 species are presented. The following species are removed from Cephaloleia: C. bipartita Pic, 1926c is transferred to Hybosispa Weise, 1910; C. minasensis Pic, 1931 and C. viridis Pic, 1931 are transferred to Stenispa Baly, 1858. The following species are described as new: C. abdita sp. n. from Brazil; C. amba sp. n. from Colombia, Ecuador, and Peru; C. angustacollis sp. n. from Ecuador; C. brevis sp. n. from French Guiana; C. calathae sp. n. from Costa Rica; C. chica sp. n. from Peru; C. conforma sp. n. from Costa Rica; C. crenulata sp. n. from Ecuador; C. gemma sp. n. from Bolivia and Brazil; C. horvitzae sp. n. from French Guiana; C. interrupta sp. n. from Costa Rica; C. kressi sp. n. from Costa Rica; C. lenticula sp. n. from Ecuador, French Guiana, Peru, and Suriname; C. nana sp. n. from Ecuador; C. ochra sp. n. from Ecuador; C. stainesi sp. n. from Costa Rica; and C. susanae sp. n. from Brazil and Ecuador. Cephaloleia simoni Pic, 1934 is treated as Incertae sedis. The larvae of C. erichsonii Baly, 1858 and C. puncticollis Baly, 1885 are described and illustrated.

Description of the last-instar larva and pupa of a leaf-mining hispine – Prionispa champaka Maulik, 1919 (Coleoptera, Chrysomelidae, Cassidinae, Oncocephalini)

Abstract The last-instar larva and pupa of Prionispa champaka Maulik, 1919 are described and figured in detail. The chaetotaxy of the head, mouthparts, legs, and dorsal and ventral surfaces of the body are given. The larva of P. champaka mine in the leaves of Pollia japonica Thunb. (Commelinaceae) and pupate in the base of the mid-ribs. The adults were also observed feeding on the leaves of Pollia siamensis (Carib.) Faden ex D. Y. Hong. The prominent diagnostic characters of immature stages of other species of the three genera of Oncocephalini (Prionispa, Chaeridiona, and Oncocephala) are discussed.

Experimental assemblage of novel plant-herbivore interactions: ecological host shifts after 40 million years of isolation

Geographic isolation is the first step in insect herbivore diet specialization. Such specialization is postulated to increase insect fitness, but may simultaneously reduce insect ability to colonize novel hosts. During the Paleocene-Eocene, plants from the order Zingiberales became isolated either in the Paleotropics or in the Neotropics. During the Cretaceous, rolled-leaf beetles diversified in the Neotropics concurrently with Neotropical Zingiberales. Using a community of Costa Rican rolled-leaf beetles and their Zingiberales host plants as study system, we explored if previous geographic isolation precludes insects to expand their diets to exotic hosts. We recorded interactions between rolled-leaf beetles and native Zingiberales by combining DNA barcodes and field records for 7450 beetles feeding on 3202 host plants. To determine phylogenetic patterns of diet expansions, we set 20 field plots including five exotic Zingiberales, recording beetles feeding on these exotic hosts. In the laboratory, using both native and exotic host plants, we reared a subset of insect species that had expanded their diets to the exotic plants. The original plant-herbivore community comprised 24 beetle species feeding on 35 native hosts, representing 103 plant-herbivore interactions. After exotic host plant introduction, 20% of the beetle species expanded their diets to exotic Zingiberales. Insects only established on exotic hosts that belong to the same plant family as their native hosts. Laboratory experiments show that beetles are able to complete development on these novel hosts. In conclusion, rolled-leaf beetles are pre-adapted to expand their diets to novel host plants even after millions of years of geographic isolation.

Monolepta meihuai, a New Species from Taiwan, with Redescription of Its Sibling Species Monolepta mandibularis Chûjô, 1962 (Coleoptera: Chrysomelidae: Galerucinae)

ABSTRACT Monolepta meihuai Lee, Tian, and Staines, new species, is described and its sibling species, Monolepta mandibularis Chûjô, 1962, is redescribed. Male and female reproductive systems are illustrated in detail. The species are distinct biologically by their host associations and times of adult appearance.

Description of immature stages and biological notes of Cassidispa relicta Medvedev, 1957, a newly recorded species from China (Coleoptera, Chrysomelidae, Cassidinae, Hispini)

Abstract The first instar and mature larva and pupa of Cassidisparelicta Medvedev, 1957, a newly recorded species from China, are described and figured. The chaetotaxy of the head, mouthparts, legs, and dorsal and ventral surfaces of the body is described. This is the first detailed description of immatures in the genus Cassidispa. Diagnostic characters of this species are compared with other described immatures of some Hispini genera. Biological notes on C.relicta, such as host plants, feeding patterns of adults, structure of larval mines and life history, are also presented.

Hemipyxis Yui, a New Species from Taiwan, with Redescription of Its Allied Species H. Quadrimaculata (Jacoby, 1892) (Coleoptera: Chrysomelidae: Galerucinae)

Hemipyxis yui Lee and Staines, new species, is described and its allied species, H. quadrimaculata (Jacoby, 1892), is redescribed. Male and female reproductive systems are illustrated in detail.