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Hybosoridae comprise five extant subfamilies (Anaidinae, Ceratocanthinae, Hybosorinae, Liparochrinae and Pachyplectrinae). The phylogenetics of Anaidinae and Ceratocanthinae have been analysed previously. This is the first thorough analysis with greater representation of the entire family, especially regarding Hybosorinae. The present study tested the monophyly of Hybosoridae; the monophyly and relationships of its subfamilies and among the genera; and the ‘incertae sedis’ placement of the hybosorid genera Borrochrus and Daimothoracodes and of Orubesa, currently assigned to Scarabaeidae. The matrix consisted of 111 morphological characters and 76 taxa. The monophyly of Hybosoridae and three subfamilies (Anaidinae, Ceratocanthinae and Liparochrinae) was supported. Few changes were necessary to recover the monophyly of Hybosorinae and Pachyplectrinae: Brenskea is transferred from Pachyplectrinae to Hybosorinae, and Borrochrus and Daimothoracodes are allocated to Pachyplectrinae. Hybosorinae include two paraphyletic genera: Apalonychus and Hybosorus. To recover their monophyly, two monotypic genera were synonymized: Hapalonychoides is now a junior subjective synonym of Apalonychus (Apalonychus similis comb. nov.) and Hybosoroides a junior subjective synonym of Hybosorus (Hybosorus alluaudi comb. nov.). Orubesa is more closely related to Ochodaeidae than to Hybosoridae.

Manonychus Moser, 1919 is composed by seven species, all endemic from Brazil, and it is placed in incertae sedis of Melolonthinae (Coleoptera: Scarabaeoidea: Scarabaeidae). This study aimed to test the monophyly of Manonychus and its position among the other genera of the subfamily. Around 184 specimens belonging to seven melolontine tribes and one orphnine were analysed. A total of 66 morphological characters of adults, including mouthparts and male genitalia were built, and 15 are a new contribution to the subfamily. Equal and implied weighting analyses were carried out using TNT program and Fitch parsimony as optimization criteria. From the equal weighting analysis a consensus of two trees was obtained with 340 steps length (ci = 0.221; ri = 0.483); and in the implied weighting analysis one tree was obtained with k = 18.920.302 steps length, and 56.28 of adjusted fit (ci = 0.245; ri = 0.550). Manonychus is monophyletic, its sister clade is composed by Ovomanonychus + (Apterodemidea + Sericoides). All these genera are nested in Sericoidini, subsidising the inclusion of Manonychus and the confirmation of Ovomanonychus in this tribe. The placement of Manonychus rufinus and Manonychus ovalis in Manonychus is corroborated.

Plectris alienaChapin, 1934, a white grub that promotes serious damage to a variety of crops in North America and Australia, has been reported for the first time in Brazil. Larvae and adults of P. aliena were recorded in sugarcane crops in the state of Mato Grosso do Sul, sampled by trenches in the soil with light traps, respectively, during 2012 and 2013. Root consumption was also determined for the first, second and third instar larvae. The species is univoltine; adults were found mainly in Aug and the peak of third instar larval density was in Apr in all fields sampled. Pupae and adults of P. aliena were observed in the soil profile at depths of up to 60 and 80 cm, respectively. Larvae of P. aliena of the second and third instar consumed the primary and secondary roots of sugarcane, causing serious damage. Third instar larvae consumed 916 mg of root fresh matter, representing 72 % of the sugarcane root system. These results assist in furthering the understanding of its larval dynamics in the soil and provide support for Integrated Pest Management.

Cnemidochroma Schmidt, 1924, a small genus of the tribe Callichromatini endemic in South America, comprises six species of which the only one recorded in Paraguay, Uruguay, Argentina and Brazil is C. phyllopus (Guérin-Méneville, 1844). The aim of this study was to estimate potential suitable areas for C. phyllopus to provide further knowledge on its current distribution. A dataset of 43 records was compiled and species distribution modelling was employed linking these occurrences with bioclimatic variables. Results indicate higher suitability conditions along the Atlantic coast of Brazil, reaching north Uruguay and extending inland to Paraguay and northern parts of Argentina. In addition, we report a new distributional record from Corrientes, Argentina.

Liogenys Guérin-Méneville, 1831, the largest genus of Neotropical Diplotaxini, is now comprised of 91 species. Fifteen new Brazilian species are described: L. acuta sp.n.; L. amazonica sp.n.; L. angustitarsis sp.n.; L. clinocarinata sp.n.; L. crassopunctata sp.n.; L. hirsuta sp.n.; L. latoemarginata sp.n.; L. leviscutata sp.n.; L. ornativentris sp.n.; L. rodriguesi sp.n.; L. pruinosa sp.n.; L. quadrata sp.n.; L. susanalbertorum sp.n.; L. variabilis sp.n.; and L. vazdemelloi sp.n.. Females are described for the first time for L. acutidens Moser, L. moseri Frey and L. sinuaticeps Moser. For L. macropelma Bates and L. minuta Moser, lectotypes and diagnoses are provided. Two new junior subjective synonyms are made for L. moseri and for L. parva Blanchard: L. obesina Frey and L. femella Cherman, respectively. The geographic distribution of Liogenys is first time recorded in Acre and Rondonia by the occurrence of new species, while other new records are expanded for eight species.

The biodiversity of northern South American and Central American Liogenys Guérin-Méneville, 1831 (Coleoptera: Scarabaeidae: Melolonthinae: Diplotaxini) is reviewed. Four new species are described: L. clipeosetosa Cherman, new species; L. genieri Smith & Cherman, new species; L. granadina Cherman, new species; and L. schneiderae Cherman, new species. The male of L. quadridens (Fabricius, 1798) and the female of L. quadridentata Blanchard, 1851 are described for the first time. Liogenys gebieni Moser, 1921 is a new junior subjective synonym of L. macropelma Bates, 1887. The northernmost record of Liogenys is emended to Trinidad and Tobago for L. granadina Cherman, new species and L. schneiderae new species. Diplotaxis puberea cuprascens (Bates, 1887) new combination, Diplotaxis puberea puberea (Bates, 1887) new combination, and Diplotaxis pubisternis (Bates, 1887) new combination are all transferred from Liogenys to Diplotaxis Kirby, 1837. Lectotypes are designated for Liogenys gebieni Moser, 1921; Melolontha quadridens Fabricius, 1798; and Liogenys quadridentatus Blanchard, 1851. An identification key to northern South American Liogenys is presented.

A taxonomic revision of the Liogenys Guérin-Méneville, 1831 (Coleoptera: Scarabaeidae: Melolonthinae: Diplotaxini) from the Chacoan Biogeographical Province is presented. Liogenys now includes 92 species, including four new species described here: L. neoforcipata Cherman, new species; L. foveata Cherman, new species; L. isotarsis Cherman, new species; and L. truncata Cherman, new species; and the female of L. tarsalis Moser is described for the first time. Six new synonymies are proposed: L. denticulata Moser, 1918 is a new synonym of L. denticeps Blanchard, 1851; L. ophtalmica Frey, 1973 is a new synonym of L. bidenticeps Moser, 1919; L. mendozana incisa Frey, 1969 is a new synonym of L. mendozana Moser, 1918; L. flavicollis Blanchard, 1851 and L. fulvescens Blanchard, 1851 are new synonyms of L. pallens Blanchard, 1851; and L. densicollis Moser, 1921 is a new synonym of L. opacicollis Fairmaire, 1892. Liogenys cribricollis Moser, 1921 species status is revalidated from its synonymy with L. densicollis. A neotype is designated for Liogenys mendozana incisa Frey, 1969, as well as lectotypes for: L. bruchi Moser, 1924; L. cribricollis, L. denticulata, L. denticeps, L. fulvescens, L. latitarsis Moser, 1918; L. mendozana Moser, 1918; L. obscura Blanchard, 1851; L. opacicollis; and L. pallens. Redescriptions and/or diagnoses and updated geographical distributions are provided for 16 species. Six species previously known only from Argentina have their distribution expanded to Bolivia (L. mendozana; L. opacicollis; L. rectangula Frey, 1969), Paraguay (L. nigrofusca Moser, 1918; L. pallens), or to both of these countries (L. latitarsis).

The biodiversity of Liogenys Guérin-Méneville, 1831 (Coleoptera: Scarabaeidae: Melolonthinae: Diplotaxini) from the southern South American Transition Zone and boundaries is presented. Four new species are described: L. brachyclypeata Cherman, new species; L. lucialmeidae Cherman, new species; L. martinezi Cherman, new species; and L. maxillaricuspis Cherman, new species. The synonymy of L. flaveola Moser, 1924 (= L. kadleci Frey, 1970) is proposed. Lectotypes are designated for L. flavida Moser, 1918; L. pallidicornis Blanchard, 1851 (currently L. xanthocera Harold, 1869); and L. rufoflava Moser, 1918. Redescriptions are provided for all the species mentioned above plus L. calcarata Frey, 1970 and L. kunzteni Moser, 1921, as well as an identification key and updated geographical distributions to all species in the region. All species are present in the Monte province, except of L. kuntzeni (Andean provinces of Chile). Liogenys flavida and L. rufoflava have the broadest distribution, the latter here expanded to Paraguay and Chile.

A common white grub species associated with a wide range of crops in Southern Brazil has been named as Cyclocephala flavipennis Arrow for over twenty years. This work aimed to revise the identity of this species based on the study of primary types, identified material collected in previous works and descriptions on literature. The confirmed name for this white grub from Southern Brazilian crops was fixed to C. signaticollis Burmeister, an important pest of several no-tilling crops in Argentina, Uruguay and also in Australia, where it was introduced and is widely established. Taxonomical remarks on adults and larvae are included, in conjunction with depicted images of diagnostic characters. The geographical distribution of C. flavipennis from Southern South America is disregarded. New strategies of pest management for C. signaticollis should be assessed in Southern Brazil taking into account all the background of knowledge on this species from the neighboring countries.

Ovomanonychus new genus (Coleoptera: Scarabaeidae: Melolonthinae: Sericoidini) is described based on Ovomanonychus rosettae (Frey, 1976), new combination (type species), Ovomanonychus inajae new species, and Ovomanonychus striatus new species. The genus occurs in Bahia, Mato Grosso, Espírito Santo, Minas Gerais, Paraná, Rio de Janeiro, and São Paulo States, Brazil. Description is provided for the new genus and for its placement in Sericoidini. A key to species is presented along with illustrations, distributional data, and a map for each species.

Diloboderus abderus (Sturm, 1826) (Coleoptera: Melolonthidae) is a serious soil pest of corn, wheat, oat, and natural and cultivated pastures in Argentina, Paraguay, Uruguay, and southern Brazil. Despite its economic importance, the genetic diversity and population structure of D. abderus remain unknown. We sequenced a fragment of the mitochondrial gene cytochrome oxidase I region (COI), of six populations of D. abderus from the Southern Cone of America. The mtDNA marker revealed a high haplotype diversity, high pairwise FST values, and significant genetic variations among populations. No correlation was found between genetic and geographical distances, yet the most common haplotype (Dab01) was present in four out of the six populations. Analysis of molecular variance showed that most of the variation was within populations of D. abderus. Tajima's D and Fu's FS tests indicated no evidence that D. abderus populations are under recent expansion. Our results indicate that genetic-based traits will likely remain localized or spread slowly, and management strategies need to be undertaken on a small scale.

Annual crops or exotic trees for cellulose extraction have replaced natural grassland areas of the Brazilian Pampa biome. These activities have been intensified in recent years and may lead to changes in the white grub complex. The objective of this study was to characterize the diversity and abundance of white grubs in cultivated and natural grassland areas of the Brazilian Pampa biome. We conducted samplings in natural grassland and cultivated areas throughout 18 locations in the Brazilian Pampa. Diversity index and nonmetric multidimensional scaling (NMDS) were used to compare the Melolonthidae community within and between cultivated and natural grassland areas. Diloboderus abderus Sturm, Cyclocephala modesta Burmeister, and Plectris sp.5 (Coleoptera: Melolonthidae) were the most abundant taxa, accounting for 49.08% of all white grubs collected from both land use types. Abundance, diversity, and evenness indices were greater in natural grassland than in cultivated areas. The NMDS demonstrated that natural grassland and cultivated areas share similar white grub species assemblages, with 22 species collected in both land use types. Our data suggest that most of the Melolonthidae species collected in the Brazilian Pampa are capable of persisting in cultivated areas. This is the first work characterizing the Melolonthidae community throughout the Brazilian Pampa, which is vital for implementing pest management tactics and conservation of beneficial species.

Diplotaxini Kirby is one of the 29 tribes of Melolonthinae with Nearctic, Neotropical, Paleartic, Afrotropical and Oriental distribution. According to the current classification, Diplotaxini is composed of 706 species described in 21 genera. Neotropical Diplotaxini comprise 94 species, of which 78 are members of Liogenys Guerin Meneville, the largest Neotropical genus. Until now, no phylogenetic studies on Diplotaxini have tested whether the tribe is natural or artificial. This study tested the relationships among Diplotaxini genera, created hypotheses for better defining them, and assessed the monophyly of Liogenys. Cladistic analyses using 167 adult morphological characters were performed. The 83 included taxa represent three subfamilies of Melolonthidae, four tribes of Melolonthinae, and most genera of Diplotaxini, with emphasis on Liogenys. The data were analysed using parsimony under equal and implied weights. In both analyses, the traditional concept of Diplotaxini is shown to be a polyphyletic assemblage. Empecta Erichson and Clypeasta Fairmaire are closely related to Melolontha melolontha (Linnaeus) and Pseudoliogenys Moser close to Myloxenoides Martinez (Tanyproctini). Pachrodema Blanchard is identified as the sister group of Liogenys. The monophyly of both Pacuvia Curtis and Homalochilus Blanchard is confirmed and the paraphyly of Diplotaxis Kirby is suggested. The analyses strongly supported the polyphyly of Liogenys. To render this genus monophyletic, we transferred L. ferrugata Mannerheim (related to M. melolontha) to Phyllophaga Harris, and L. micropyga Burmeister to Diplotaxis, forming Diplotaxis micropyga (Burmeister, 1855) comb.n.; and included Homoliogenys tarsalis (Moser) and Hilarianus anguliceps Blanchard in Liogenys. As H. anguliceps is syn. junior of Liogenys punctaticollis, Hilarianus is synonymized with Liogenys. Hilarianus ovalis and Hilarianus rufinus are here assigned to Manonychus, and Hilarianus uniformis and Hilarianus suboblongus to Blepharotoma, forming: Blepharotoma uniformis comb.n., Blepharotoma suboblongus comb.n., Manonychus ovalis comb.n. and Manonychus rufinus comb.n.

The replacement of natural grassland by cultivated areas might favor the increase in abundance of some root-feeding species such as the white grubs, which may become a constraint for field crop production. This research aimed to assay the population density and geographical distribution of white grubs pest and other species in natural grassland and cultivated areas throughout the Brazilian Pampa biome. White grubs were sampled in 18 locations in both landscape use types and identified. Population density (number of larvae m−2) was calculated for each recorded species and sorted within two groups (pest species and other species), compared between natural grasslands and cultivated areas, as well as among locations. A dendrogram to evaluate species similarity among locations was built based on combined data obtained from both landscape use types throughout the region. In total, 31 species were found in the Brazilian Pampa, and four of them are considered as crop pests: Diloboderus abderus (Sturm, 1826), Euetheola humilis (Burmeister, 1847), Lyogenys fusca (Blanchard, 1830), and Phyllophaga triticophaga Morón & Salvadori, 1998. The average population density of pest species in cultivated areas was less than five larvae m−2, at most of locations. Some species had a wide geographical distribution (e.g. D. abderus and Cyclocephala modesta Burmeister), while other melolontids occurred at only one location. The knowledge of which white grub species are present in a field and its population densities assist farmers to take proper management decisions. Keywords: Population density, Diloboderus abderus, Plectris, Grasslands, Cultivated areas

Cyclocephala flavipennis Arrow, 1914 (Coleoptera: Melolonthidae), popularly known as white grub, is an insect widely disseminated in the South Region of Brazil. Despite the frequent occurrence of this white grub in areas cultivated with winter cereals, it is generally not considered a pest, since it feeds on straw and dead plant material. However, in 2015 and 2016, this insect has been identified as the damage-causing agent in the perennial winter pastures in Lages, Santa Catarina, Brazil. Damage was observed in patches and caused reduction in root depth and mass, resulting in loss of vigor, accelerated senescence in aerial parts, and death of tillers in Festuca arundinacea Schreb. and Dactylis glomerata L. plants. RESUMO: Cyclocephala flavipennis Arrow, 1914 (Coleoptera: Melolonthidae), conhecido popularmente como coró-pequeno, é um inseto amplamente disseminado na região sul do Brasil. Embora seja encontrado com frequência em áreas cultivadas com cereais de inverno não é considerado inseto praga, por alimentar-se preferencialmente de palha e restos de plantas. Entretanto, nos anos de 2015 e 2016 foi identificado como causador de danos em pastagens perenes de inverno em Lages, Santa Catarina, Brasil. Os danos foram observados em reboleiras e promoveram redução na massa e profundidade de raízes, resultando em perda de vigor, senescência acelerada da parte aérea e morte de perfilhos de plantas de Festuca arundinacea Schreb. e Dacytilis glomerata L.

Comparative studies on the density and diversity of white grubs community (Coleoptera: Melolonthidae) occurring in cultivated and noncultivated fields of the Planalto region of the state of Rio Grande do Sul, Brazil, are presented. Sampling was carried out in 23 municipalities during the 2009 and 2010 winter seasons. Cultivated and noncultivated fields were chosen in each locality. Melolontid larvae were collected for identification and counted to determine the population density. A mean of 12.9 larvae m(-2) were collected in cultivated areas against 10.5 larvae m(-2) in noncultivated areas. The latter were more diverse (H' = 2.52) than cultivated areas (H' = 2.26). Despite the high evenness index (J = 0.75 noncultivated and J = 0.74 cultivated), faunistic parameters indicated Cyclocephala flavipennis Arrow and Diloboderus abderus Sturm as an extremely dominant species in cultivated areas. These results showed that the population density of white grubs increases, and their community composition is affected in cultivated areas.

No Brasil, existem registradas aproximadamente mil espécies de corós, destacando-se, dentre os de maior importância, Diloboderus abderus Sturm, 1826 (Coleoptera: Melolonthidae), pelos prejuízos que pode causar aos cultivos agrícolas e a ampla ocorrência geográfica. O trabalho teve por objetivo caracterizar, com uso da geoestatística, a distribuição espacial de larvas de D. abderus. O estudo foi realizado no ano de 2009, em lavouras de aveia nos municípios de São Francisco de Assis, Cruz Alta e Lagoa Vermelha, RS. Os perímetros das áreas foram demarcados com receptor de sistema de posicionamento global, e os grides de amostragem tiveram dimensão de 70x70m. A densidade populacional foi estimada com abertura de uma trincheira em cada ponto amostral. As análises da variabilidade espacial e da dependência espacial foram feitas por meio de semivariogramas e classificadas segundo CAMBARDELLA et al. (1994). Já os mapas foram gerados a partir dos dados de contagem de larvas em campo. Os semivariogramas indicam a presença de dependência espacial nas áreas de avaliação. Os grides de amostragem mostraram-se apropriados para caracterizar a distribuição espacial de larvas de D. abderus. A distribuição espacial de D. abderus é agregada e seu conhecimento pode melhorar o manejo da praga. In Brazil, there are about a thousand recorded species of white grubs, and among them the most important is Diloboderus abderus Sturm, 1826 (Coleoptera: Melolonthidae), because of the damage caused to agricultural crops and the wide geographic occurrence. The study aimed to characterize, using geostatistical, the spatial distribution of larvae of D. abderus. The study was conducted during 2009 in oat crops in the counties of São Francisco de Assis, Cruz Alta and Lagoa Vermelha, RS. The perimeters of the fields were delimited with global positioning system receptor, and the sampling grids dimensions were 70x70m. The population density was estimated by opening a trench in each sampling point. The analysis of spatial variability and spatial dependence were made by semivariograms and classified from CAMBARDELLA et al. (1994). Maps were generated from the counting data of larvae in the field. The semivariograms indicate the presence of spatial dependence in the assessment areas. The sampling grids proved to be suitable to characterize the spatial distribution of D. abderus larvae. The spatial distribution of D. abderus is aggregated and this knowledge may improve pest management.

First record of species of Liogenys (Coleoptera, Melolonthidae) associated with winter crops in Rio Grande do Sul (Brazil). Some species of Liogenys Guerín-Meneville, 1831 are known to cause damage to soybean, corn and other summer crops in the Brazilian "Cerrado" region. This work aimed to identify melolontid larvae associated with winter crops in Rio Grande do Sul state. Larvae and adults of Liogenys species were collected from the municipalities of Ijuí, Cruz Alta, Manoel Viana, São Luiz Gonzaga and São Francisco de Assis. The specimens were identified as L. bidenticeps Moser, 1919; L. fusca Blanchard, 1851, L. obesa Burmeister, 1855, and L. sinuaticeps Moser, 1918. This is the first record of these species associated with winter grain crops, for Rio Grande do Sul State. Biological and behavioral studies are necessary to confirm their association with host plants.Primeiro registro de ocorrência de espécies de Liogenys (Coleoptera, Melolonthidae) associadas a culturas de inverno no Rio Grande do Sul (Brasil). As espécies de Liogenys Guerín-Meneville, 1831 são conhecidas no "Cerrado" brasileiro por causar danos em culturas de verão como soja e milho. O trabalho teve por objetivo identificar as larvas de melolontídeos que ocorrem nas culturas de grãos de inverno no Rio Grande do Sul. Larvas e adultos de Liogenys foram coletados nos municípios de Ijuí, Cruz Alta, Manoel Viana, São Luiz Gonzaga e São Francisco de Assis. As espécies foram identificadas como Liogenys bidenticeps Moser, 1919, L. fusca Blanchard, 1851, L. obesa Burmeister, 1855 and L. sinuaticeps Moser, 1918. Trata-se do primeiro registro de ocorrência destas espécies associadas a culturas de grãos de inverno, no Estado de Rio Grande do Sul. São necessários estudos de biologia e comportamento para confirmar sua associação com plantas hospedeiras.

White grubs (Coleoptera, Melolonthidae) in the "Planalto Region", Rio Grande do Sul state, Brazil: Key for identification, species richness and distribution. The objective of this study was to survey the occurrence and geographic distribution of white grub species (Coleoptera, Melolonthidae) in cultivated and non-cultivated fields of the "Planalto Region", Rio Grande do Sul state, Brazil and develop a key at genus-level. Twenty-eight species from 15 genera and three subfamilies were recorded: Dynastinae, Melolonthinae and Rutelinae. The species or genera recorded for the first time in the state are: Cyclocephala metrica, C. tucumana, Isonychus albicinctus, Liogenys bidenticeps, L. fusca, L. obesa and L. sinuaticeps, Paranomala violacea, as well as unidentified species of Amononyx, Dicrania, Leucothyreus, Macrodactylus, Plectris and Rhizogeniates. Among the species recorded, 23 were associated with winter crops. Only Cyclocephala metrica, Dyscinetus rugifrons, two species of Leucothyreus and one species of the tribe Sericini were not present in cultivated crop fields. Cyclocephala flavipennis and Diloboderus abderus occurred in most of the municipalities sampled, often associated with Plectris sp., C. modesta and C. putrida. The highest richness of melolonthids was concentrated in the northeast of the Planalto region.

É importante quantificar a densidade populacional de corós para definir o momento adequado para o controle da praga. Assim, o objetivo deste trabalho foi determinar o tamanho de amostra (número de trincheiras por hectare) para a estimação da média de densidade populacional de corós em áreas de campo nativo e de cultivo em diferentes locais do Estado do Rio Grande do Sul. Foram coletados dados de densidade populacional de corós, independentemente de espécie, em áreas de campo nativo e de cultivo em 17 locais, por meio de contagens realizadas em trincheiras de 20cm x 50cm com 30cm de profundidade. Em cada uma das 34 áreas amostradas, calcularam-se medidas de tendência central, de variabilidade, de assimetria e de curtose, e testou-se a normalidade dos dados. Em seguida, verificou-se a homogeneidade de variâncias entre as áreas em cada local e entre os locais em cada área. Depois, calculou-se o tamanho de amostra em cada área e local. O tamanho de amostra (número de trincheiras por hectare) para a estimação da média de densidade populacional de corós é dependente da área (campo nativo ou de cultivo) e do local. Para as áreas e os locais estudados, 61 trincheiras por hectare são suficientes para estimar a média de densidade populacional de corós, para um erro de estimação igual a 30% da média estimada, com grau de confiança de 95%. It is important to quantify the population density of white grub to set the appropriate time to control the pest. The aim of this study was to determine the sample size (number of trenches per hectare) to estimate the average population density of white grubs in native and cultivated areas in different locations of Rio Grande do Sul State, Brazil. Data were collected from white grubs' population density in native and cultivated areas of 17 locations, regardless of species, through counts in trenches 20cm x 50cm dug to a depth of 30cm. In each of the 34 areas sampled, the central tendency, variability, asymmetry and kurtosis was calculated and the normality data were tested. Then it was verified the homogeneity of variance among areas in each locality and among locations in each area and it was determined the sample size to estimate the average population density of white grubs in each area and locality. The sample size (number of trenches per hectare) to estimate the average population density of white grubs is dependent on the area (native or cultivated) and locality. It was concluded that 61 trenches per hectare are enough to predict the average population density of white grubs, with an estimation error equal to 30% of estimated average, with a degree confidence of 95%.

La familia Melolonthidae Leach, 1819 fue definida por Endrödi en 1966 como un grupo cosmopolita compuesto principalmente por las subfamilias Melolonthinae, Dynastinae, Rutelinae y Cetoniinae, formadas por taxones con hábitos fitófagos o fitosaprófagos, a diferencia de otros grupos de Scarabaeoidea. A pesar de ser ampliamente utilizada en América Latina desde 1976, esta clasificación es cuestionada por autores de estudios morfológicos y filogenéticos que apoyan la clasificación utilizada en América del Norte, la cual agrupa las subfamilias citadas junto con los Scarabaeinae y Aphodiinae coprófagos dentro de la familia Scarabaeidae Latreille, 1802. La presente revisión tiene como objetivo apoyar la validez de la familia Melolonthidae con modificaciones. Para ello se compararon diferentes clasificaciones utilizadas a lo largo de la historia de la coleopterología, así como los análisis para relacionar los diferentes grupos de Scarabaeoidea que se han publicado recientemente. Con dicha información y a reserva de efectuar nuevos estudios de morfología comparada y de obtener mejores datos con técnicas moleculares para apoyar un análisis filogenético más preciso, en el presente trabajo se propone aceptar como válido el nombre del agrupamiento denominado Melolonthidae constituído por el clado Dynastinae-Rutelinae-Melolonthinae. También se sugiere retirar a los Cetoniinae de aquel grupo y elevarlos a la categoría de familia, así como comprobar las relaciones de la subfamilia Orphninae con respecto a los miembros de la familia Melolonthidae. Finalmente, se indica que para lograr un consenso global sobre la clasificación supragenérica de los Melolonthidae es necesario efectuar análisis filogenéticos con taxones de todas las regiones del mundo, que efectivamente representen la riqueza específica de cada subfamilia y tribu, utilizando caracteres de larvas y adultos para confirmar su monofilia y las relaciones con otros grupos de Scarabaeoidea.