Research Article |
Corresponding author: Vivian Flinte ( vflinte@gmail.com ) Academic editor: Michael Schmitt
© 2015 Vivian Flinte, Ethel Hentz, Barbara Morgado, Anne Lima, Gabriel Khattar, Ricardo Monteiro, Margarete Macedo.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Flinte V, Hentz E, Morgado BM, Lima ACM, Khattar G, Monteiro RF, Macedo MV (2015) Biology and phenology of three leaf beetle species (Chrysomelidae) in a montane forest in southeast Brazil. In: Jolivet P, Santiago-Blay J, Schmitt M (Eds) Research on Chrysomelidae 5. ZooKeys 547: 119–132. https://doi.org/10.3897/zookeys.547.9015
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The population phenology of the cassidines, Coptocycla arcuata and Omaspides trichroa, and the chrysomeline, Platyphora axillaris, was studied at Serra dos Órgãos National Park, State of Rio de Janeiro, southeast Brazil. Monthly surveys of larvae and adults were conducted between 2008 and 2011 at approximately 1000 m altitude on their respective host plants, Cordia polycephala (Boraginaceae), Ipomoea philomega (Convolvulaceae) and Solanum scuticum (Solanaceae). This is the first observation of larviparity and host record for P. axillaris. Although having different life history traits, all species showed similar phenologies. They were abundant from October to March, months of high temperatures and intense rainfall, with two distinct reproductive peaks in the same season. Abundance dropped abruptly during the coldest and driest months, from May to August. Frequently none of these species were recorded during June and July. This phenological pattern is similar to other Chrysomelidae living in subtropical areas of Brazil. Temperature and rainfall appear to be the major factors influencing the fluctuation of these three species.
Population fluctuation, viviparity, host plant, altitude, climate
Phenology can be considered a temporal dimension of natural history, and because both include timing of growth, reproduction and senescence, they are sometimes used as synonyms (
The role of abiotic variables in species phenology increases concern in how climatic change will affect species’ temporal and spatial distributions. Efforts are being made to predict biotic responses in relation to abiotic changes (see references in
Interestingly, previous studies on Chrysomelidae in Brazil (e.g.
Surveys were undertaken along the main road of the Serra dos Órgãos National Park (22°26'56"S and 42°59'5"W) in the county of Teresópolis, at approximately 1000 m altitude, characterized by montane rain forest. The Park lies in a mountainous area of the State of Rio de Janeiro, southeast Brazil, with elevations extending from 80 to 2263 m a.s.l. The climate in the region is tropical mesothermic (
Our study focuses on three abundant chrysomelid species previously observed by the author in the area, two cassidines and one chrysomeline. Study periods varied by species, but generally corresponded to the period from November 2008 to June 2011. Host plants were marked and thoroughly inspected for insects in periodic surveys, but it was not uncommon for plants to be accidentally cut down or to disappear during the study, which can explain some differences in host numbers between consecutive surveys. Host plant numbers and survey periods are presented below for each study species.
Coptocycla (Podostraba) arcuata (Swederus, 1787) (Cassidinae: Cassidini) feeds on the small shrub, Cordia polycephala (Boraginaceae) (
Omaspides (s. str.) trichroa (Boheman, 1854) (Cassidinae: Stolaini) feeds on the vine Ipomoea philomega (Convolvulaceae) (
Platyphora axillaris Germar, 1824 (Chrysomelinae) feeds on the shrub Solanum scuticum (Solanaceae) and was studied from February 2009 to June 2011 (between one and four surveys per month). A total of 29 months and 78 surveys were conducted for this species. The number of plants surveyed varied from 14 to 46. There are no published accounts of this species.
During inspection, adults and larvae of all species, and eggs of O. trichroa, were counted and observations were made regarding life history and behavior traits. Beetles were on occasions brought to the laboratory and reared in plastic containers with host plant leaves to complement field observations and to obtain parasitoids. Parasitized egg masses of O. trichroa found in field were brought to the lab to obtain parasitism rates within clutches. The total number of records of adults and larvae on upper and lower sides of the leaves was also registered. Although it is possible that the same individual was recorded more than once, adults and larvae of the studied species are mobile, so their location could vary from one survey to another. Beetle, plant and parasitoid specimens are deposited in the collection of the Laboratório de Ecologia de Insetos, Universidade Federal do Rio de Janeiro, Brazil.
Due to the different numbers of host plants inspected on each survey we calculated the density of insects per plant for each beetle species to describe patterns of phenology. In addition to adults and larvae, densities were also calculated for egg masses and larval aggregations of O. trichroa, and for young larvae of C. arcuata, as eggs are difficult to find in field. Densities were calculated separately for each survey, multiplied by 100 (to avoid decimals) and finally the mean density was determined for each month. Thus, a monthly mean density of 200, for example, indicates that for that stage, on average, 200 individuals were found per 100 plants on a given month, or two individuals per plant. Plant phenology was evaluated simply by the presence or absence of new leaf shoots for each individual inspected on each survey. The percentage of host plants with new shoots was calculated for each survey, dividing the number of plants with new shoots by the number of plants inspected and multiplying the result by 100. The mean percentage was then calculated for each month. The monthly mean density of beetles was correlated (Pearson correlation) with plant phenology and climate variables (temperature and rainfall). Lagged correlations of one, two and three months were made as well. The percentage of plants occupied by beetles (adult or larva) was also calculated to evaluate the intensity of attacks on plants and the spatial distribution of beetles on their host plants. Here, for each survey, the number of attacked plants was divided by the number of surveyed plants and multiplied by 100 to be expressed as percentage; then the mean and maximum percentages (considering all surveys) were established.
Coptocycla arcuata deposits single, flattened, membranous eggs, and O. trichroa deposits a mass of hard elliptical eggs which are guarded by the mother; both species lay eggs on the underside of leaves (n = 6 for C. arcuata and n = 167 records for O. trichroa). The solitary larvae of C. arcuata carry an exuvio-fecal shield, resembling an elliptical blob of wet feces (Fig.
Percentage and total number of records of adults and larvae (larval aggregations for O. trichroa) on the upper and lower side of host plant leaves.
Species | Stage | Upper side (%) | Lower side (%) | N |
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Coptocycla arcuata | Adults | 61.5 | 38.5 | 422 |
Larvae | 1.5 | 98.5 | 67 | |
Omaspides trichroa | Adults | 2.9 | 97.1 | 888 |
Larval aggregations | 0.0 | 100.0 | 190 | |
Platyphora axillaris | Adults | 76.2 | 23.8 | 632 |
Larvae | 8.3 | 91.7 | 223 |
The phoretic wasp Emersonella pubipennis Hansson, 2002 (Hymenoptera: Eulophidae) (Fig.
Densities of the three chrysomelid species varied similarly throughout the year, with higher numbers from October to March (spring and summer), and lower numbers or even absence of beetles from June to August (Fig.
Population phenology of C. arcuata (A), O. trichroa (B) and P. axillaris (C) in a montane forest at 1000 m altitude between November 2008 and June 2011. A climatic diagram (data obtained from a meteorological station in the same site) is given for the same period as surveys (D). Dotted area = dry period; striped area = humid period; black area = super-humid period. The line above species fluctuations represents the percentage of host plant with new leaf shoots, the dotted line being < 25% of plants in this phase; fine line between 25% and 75%; thick line > 75%.
Omaspides trichroa was studied during two whole reproductive seasons, 2009/2010 and 2010/2011. Adults and egg masses started to be found in September 2009 in the first season and in October 2010 in the second season, and larvae always appeared one month later. Densities of egg masses and larvae peaked right away, then decreased abruptly in November (eggs) and December 2009 (larvae), increasing again and peaking once more in January (eggs) and February 2010 (larvae). Exactly the same pattern was observed in the following season, with exception that densities of eggs and larvae decreased together in December 2010. Density of adults also showed this bimodal pattern of occurrence in two consecutive seasons. Densities of all stages then decreased rapidly and disappeared completely from May until the following season. Studies on C. arcuata started in the beginning of the reproductive season 2009/2010 and extended until the end of the season 2010/2011. Adults were first found in September, and larvae one month later. Density of young larvae (as an approximation of the egg stage) and total larval density varied similarly, peaking in the first season in January 2010 and in the second season in December 2010, decreasing and reaching another peak in March 2010 and February 2011. Adults of this species also showed two peaks of occurrence. Platyphora axillaris was studied also during seasons 2009/2010 and 2010/2011. Densities of adults peaked at least twice in each reproductive season, once or twice in the end of the year and then again in March, and their larvae earlier in October and a second time in March, during two consecutive seasons. Overall, densities of all stages showed two peaks in each reproductive season for the three species, suggesting the existence of two generations per year, i.e. bivoltine reproduction. Numbers of all species decreased in April and some completely disappeared in subsequent months, increasing again in September (Fig.
The seasonal fluctuation of beetle densities correlated with variations of temperature and rainfall throughout the year, with high numbers coinciding with super-humid periods (precipitation above 100 mm per month) and warmer months in the study area (Fig.
Correlations (Pearson) between monthly mean density of adults and larvae of C. arcuata, O. trichroa and P. axillaris and monthly mean temperature, total precipitation per month and monthly mean percentage of plants with new shoots. For O. trichroa densities of larval aggregations are given. Number of months used are given by n.
Species | Stage | Temperature (°C) | Precipitation (mm) | Plants with new shoots |
---|---|---|---|---|
Coptocycla arcuata | adults | r = 0.922*** (n=20) | r = 0.493* (n=20) | r = -0.191 (n=20) |
larvae | r = 0.655** (n=20) | r = 0.267 (n=20) | r = 0.014 (n=20) | |
Omaspides trichroa | adults | r = 0.665*** (n=29) | r = 0.702*** (n=29) | r = 0.410* (n=29) |
aggregations | r = 0.422* (n=29) | r = 0.260 (n=29) | r = 0.280 (n=29) | |
Platyphora axillaris | adults | r = 0.608*** (n=29) | r = 0.728*** (n=29) | r = 0.319 (n=18) |
larvae | r = 0.218 (n=29) | r = 0.558** (n=29) | r = 0.336 (n=18) |
Although fluctuation patterns were similar among species, their numbers could differ by an order of magnitude, especially for O. trichroa, in which larval density reached 17 times that of the adults (for larval aggregations the number was six times higher than adults). For the other two species, adults were generally more abundant than larvae (Fig.
This study describes aspects of the natural history and phenology for three Chrysomelidae species occurring at 1000 m altitude in SE Brazil. Our results document that, despite differences in life history traits occurring among these three taxonomically distinct species, all present a similar two-peak pattern of reproduction during the warmest and wettest months of the year. Below our findings are discussed in the context of previous reports on Neotropical Chrysomelidae.
Earlier studies documented that O. trichroa feeds on only a single plant species at the study area, whereas C. arcuata feeds on two related plants (
The preferences of adults of C. arcuata and P. axillaris for the upper side of leaves (Table
Clearly, the three Chrysomelidae species have very different life histories and a distinct array of defenses. Platyphora axillaris is larviparous with no maternal care, while O. trichroa is oviparous, with females caring for their young and larvae carrying an exuvio-fecal shield on their dorsum; both species are monophagous at the study area. Coptocycla arcuata, on the other hand, is oligophagous, feeding on two plant species, but oviparous without maternal care and with larvae also carrying a shield. Despite these significant differences between the three species, they showed very similar population phenologies (Fig.
Our findings corroborate other studies on Chrysomelidae in the same area (
Variation in the order of magnitude of species numbers, especially the much larger density of O. trichroa larvae, can possibly be explained by the behavior of maternal care, which increases immature survivorship (
Despite considerable differences in life history traits and systematic position among the three chrysomelid species, our data suggest that they are bivoltine, disappearing during the unfavorable period of lower temperatures, a pattern similar to species in subtropical regions and other species already studied in the same area. The climatic variables of temperature and precipitation seem to be important drivers for species phenologies. In light of the undergoing climatic changes, studies on insects and their host plants on mountains can provide an important tool for studying the responses of species to changing environmental conditions, predicting possible future scenarios and collaborating with species conservation efforts.
We thank Lech Borowiec (University of Wroclaw, Poland) and Mauro Daccordi (Museo Civico di Storia Naturale, Italy) for the identification of the Cassidinae and Chrysomelinae species, respectively. Parasitoids were identified by André Nascimento (UFSCAR) and Valmir Costa (Instituto Biológico, SP). For plant identification we thank Elsie Franklin Guimarães (Boraginaceae, Jardim Botânico do Rio de Janeiro), Rosângela Simão-Bianchini (Convolvulaceae, Herbário SP) and Lucia d’Ávila Freire de Carvalho (Solanaceae, Jardim Botânico do Rio de Janeiro). We are grateful to the lab crew for field support and to C. Cronemberger from ICMBIO/PARNASO for logistic support. We are thankful to Donald Windsor (STRI, Panama) and an anonymous reviewer for valuable suggestions on the manuscript. Our research authorizations were 214/2005, 246/2006 and 13424-1. VF received scholarship from CAPES, CNPq and FAPERJ, BMM from CNPq/PIBIC, EH from CNPQ and ACML from FAPERJ. RFM acknowledges the support of CNPq through its Scientific Productivity Scholarship. The authors also thank CNPq, CAPES and FAPESP (Instituto Nacional de Ciência e Tecnologia HYMPAR - Sudeste, Brazil) and FAPERJ (PENSA-Rio) for financial support.
Extended version of a presentation to the 2nd European Symposium on the Chrysomelidae, York (England), August 4, 2014