Abundance of Heteropsylla cubana population and its natural enemies in Leucaena leucocephala agroecosystems

Nurys Valenciaga Valdés, T E Ruiz Vázquez, L Ramirez-Avilés¹ and D Parsons²

Instituto de Ciencia Animal, Carretera Central km 47 ½, Apartado postal 24, San José de las Lajas, Mayabeque, Cuba
nvalenciaga@ica.co.cu
¹ Universidad Autónoma de Yucatán, Carretera 15.5 Mérida-Xmatkuil, México
² University of Tasmania, School of Land and Food. Private Bag 98, Hobart, Tasmania, Australia

Abstract

At the risk of the presence of Heteropsylla cubana Crawford could limit the use of leucaena. The present work was conducted in different Leucaena leucocephala agroecosystems, in their initial stages after the intercropping of seasonal crops, with different years of establishment and presence or not of other trees in the system. The objective was to evaluate the abundance of H. cubana population in L. leucocephala agroecosystems and understand its enemies naturals associated to leucaena pyllid. Periodic random samplings of the associated arthropods were carried out. The collected species were identified taxonomically and classified according to their feeding habit. Bivariate correlation and principal components analysis were applied. The results showed that H. cubana is the phytophagou main in L. leucocephala sowings. A complex of natural enemies grouped in 4 classes, 8 orders, 12 families, and 21 genera was detected. H. cubana population density was higher in less diverse sowings. Criteria are provided to keep the populations under non-harmful levels. It is concluded that despite the abundance shown by H. cubana, in the dry season, in areas of L. leucocephala , favored by the climatic conditions in the period. There is a permanence of natural enemies of the leucaena psyllid, under Cuban conditions, given by predators, parasitoids and entomopathogens that favor their control. It is recommended to favor or increase the presence of these natural enemies in the agroecosystem to prevent economic damage to the legume and to continue promoting the use of the tree as animal feed.

Key words: beneficial organisms, Fabaceae, livestock, phytophagous pest, psyllid

Introduction

The introduction of leucaena (Leucaena leucocephala (Lam.) de Wit) in livestock production systems, either as protein bank (Milera et al 1994), associated to grass pastures in the whole farm or as a cut and curry system, has a positive effect on animal performance, due to high availability (Jordán 2012) and quality of forage (Galindo 2001; Shelton 2017). This has resulted in high live weight gain and increased milk production (Castillo et al 2012; Mohammed et al 2015).

Given these advantages, in Cuba, leucaena is one of the most important trees for livestock used to address the shortage of feed (Jordán 2000; Ruiz et al 2019). In addition, it has been demonstrated that this plant is able to conserve the vegetable biodiversity and animal and to contribute to mitigate the effects of the climatic change (Milera 2013; Rivera-Herrera et al 2017). However, the increasing planting of leucaena, in countries of America and the Caribbean, has also led to increased populations of H. cubana (Schultze-Kraft 1994). Leucaena psyllid is one of the pests that have killed large leucaena plantation in Asia, where it has had a high economic impact; in facto Bray and Woodroffe (1991) has reported losses of foliage leaves close to 80 % associated to psyllid infestation in the cv. Cunnigham. Thus, there is a risk that the presence of H. cubana Crawford could limit the use of leucaena. There are both biotic and climatic factors that can affect H. cubana population. The objective was to evaluate the abundance of Heteropsylla cubana population in Leucaena leucocephala agroecosystems and understand its enemies naturals associated to leucaena pyllid.

Materials and methods

Study area

The current study was undertaken in contrasting agroecosystems based on L. leucocephala and guinea (Megathyrsus maximus= Panicum maximum) at the Institute of Animal Science (ICA), located in San Jose de las Lajas municipality, Mayabeque province, Cuba.

Agroecosystems evaluated

In all agroecosystems, guinea was present as a grass base; L. leucocephala was sown in rows allowing to the methodology described by Ruiz and Febles (1999) on a typical red ferrallitic soil (Hernández et al 2015), equivalent to the rodic ferrallic cambisol subtype, according to the FAO-UNESCO classification (Durán and Pérez 1994).This methodology includes, at the early stages of development, intercropping with annual crops such as maize (Zea mays) and vigna ( Vigna unguiculata) two or three weeks after leucaena is sown. Following this methodology, the leucaena-guinea-maize agroecosystems, sown either 15 (maize-15d) or 40 (maize-40d) days after leucaena sowing, and leucaena-guinea-vigna agroecosystem, sown 15 days (vigna-15d) after leucaena sowing, were included in the evaluation (Table 1).

The other agroecosystems evaluated included the following trees species: lysiloma (Lysiloma bahamensis), gmelina (Gmelina arborea ), neem (Azadirachta indica), terminalia (Terminalia sp.) and combinations of neem with gmelina. All of them were sown at the same time as leucaena. In addition, two agroecosystems were evaluated, both with leucaena-guinea, one with contrasting years after of establishment (3 and 15 years) and other agroecosystem with two years after of establishment (Area 1 and 2).

Detailed sampling method

The evaluated agroecosystems, the sampling size and frequency, the length of the experimental period and plot size are shown in Table 1. Sampling was undertaken following the methodology described by Fernandez (1995). It proposes the equal division of the areas in five blocks. For the capture of the different states of H. cubana, four shoots in each block were taken at random in all agroecosystems, without taking into account the cardinal location according to Valenciaga et al (2005). The technique described by Mangoendihardjo et al (1990) consists of enclosing the tip of a leucaena shoot in a transparent plastic bag and removing the tip carefully.

Furthermore, samples were taken with the help of the entomological net in the agroecosystems under study according to Table 1. This was manipulated by the handle and was launched towards the aerial part of the plant to capture mainly winged insects associated with the legume. The operation was repeated until the total number of raids per sample was completed. Only in the case of the leucaena-guinea-maize (15d) agroecosystem, in which a psyllid population was counted, in the field, in 60 plants at random. The observation was directed to its sprouts. To favor the counting of eggs, nymphs and adults, a 10X magnifying glass was used.

Samples were placed into tagged plastic bags and taken to the ICA’s Entomological Laboratory for their identification. All samples, except the sprouts, were placed in an oven 40^oC for 10 minutes to kill all insects and facilitate their extraction. The specimens were grouped according to morpho-species and were placed in bottles with 70% ethyl alcohol to preserve the samples for later identification.

The infested sprout samples were placed in Petri dishes with moistened cotton, with sterile distilled water, at the base. This observation was daily until the leucaena psyllid's biological cycle was completed.

Taxonomic identification

Taxonomic identification was performed using a stereoscopic microscope and keys reported by Mendoza (1988), Zayas (1988) and the entomological ICA’s collections. A representative sample of adult specimens of leucaena psyllid was taken in each of the agroecosystems studied to corroborate through of their external genitalia the correct taxonomic identification. For which the biological microscope Karl Zeiss was used with a magnifying power 10x or 20x and the keys of Hodkinson and White (1979) according to the description of Muddiman et al (1992).

Determination of natural enemies of H. cubana

The study of the determination of natural enemies of the psyllid H. cubana focused on areas 1 and 2 during 60 months. The methodology of Mangoendihardjo et al (1990) was used for collecting eggs, larvae, nymphs, adults and apterous organisms, associated to the sprouts.

The samples contained in plastic bags were conveniently identified and transferred to the laboratory where, under the stereoscopic microscope, the healthy and parasitized development states present were recorded. Subsequently, the infested sprout samples were placed in Petri dishes with moistened cotton, with sterile distilled water, at the base. This observation was daily until the insect's biological cycle was completed. The emerged organisms were counted and placed in bottles with 70% ethyl alcohol to proceed to their subsequent identification with codes for the purposes and competent taxonomists.

The developmental stages (nymphs and adults) detected dead were extracted and placed individually in a humid chamber. The emerging pathogens were isolated and identified by competent microbiologists who carried out the necessary protocols for their correct identification.

In the case of the predators detected in the study, several tests were established, by type of identified morpho-species, under insectary conditions in the laboratory, where nymphs and adults of H. cubana , rearing in laboratory, were supplied to verify their activity against the psyllid.

Assignment of the functional groups

The species collected were classified according to the literature information about their life histories and their main eating habit based on Metcalf and Flint (1965), Triplehorn and Johnson (2005), Mancina and Cruz (2017) and World Spider Catalog (2020). In addition, observations made in the field and laboratory was taken into account. In this sense, phytophagous insects and beneficial organisms (natural enemies) were considered as functional groups, and in the latter, they were included as subgroups: predators, parasitoids, pollinators and entomopathogens.

Evaluated variables

The abundance of H. cubana in the different agroecosystems was calculated. Highest population of H. cubana within one sample in each agroecosystem.

Others phytophagousand the leucaena psyllid’s natural enemies were grouped into orders, families, genera and species according to the taxonomic identification.The organ of the plant that inhabits each phytophagous associated to leucaena was identified.

The climatic factors (relative humidity; maximum, minimum, and mean temperatures; rainfall, and number of rainy days) were recorded by the meteorological station located at around 400 m from the experimental areas.

Statistical Analysis

The H. cubana population behavior in the different agroecosystems was assessed using a comparison analysis of multiple proportions (Snedecor and Cochran 1969) and Duncan’s test to compare means (Duncan 1955).

A bivariate correlation analysis (Quevedo 1993; Torres et al 1993) was used to determine the correlation coefficients between H. cubana number, collected in each sample, and climatic factors recorded.

In the analysis of main components was applied from the Pearson correlation matrix calculation to find the correlation coefficients between H. cubana population density and its natural enemies (spiders, ants, and coccinellids), with climatic factors (temperature, relative humidity and rainfall), for sampling, in order to know the grouping in both studied areas (Area 1 and 2).

It was taken as a criterion for analysis, those main components that had its own value higher than one and sum factor or preponderance superior at 0.60, since they explain more than 50% of the variability among the study indicators.

A diagram was elaborated, starting from the obtained results, that they explains the influence of the factors in the simulation of the system, whose theoretical base allowed to propose alternatives for the handling of H. cubana under the study conditions.

Results and discussion

Taxonomic identification

The results showed that H. cubana Crawford (Hemiptera: Psyllidae) is the main phytophagous in L. leucocephala sowings. Despite the fact that in agroecosystems with L. leucocephala there were several plant eating insects, H. cubana did not have to compete with other species for vital space since they are the only insect that lives on the re-growth of leucaena. Regrowth is promoted by livestock consumption and by pruning undertaken as a part of the system management (Table 2). These results could be associated with the fact thatL. leucocephala is the plant species most attacked by H. cubana (Finlay-Doney and Walter 2005). Valenciaga et al (2010) found that in silvopastoral systems with L. leucocephala and M. maximus, H. cubana populations in the regrowth of the legume were 50% larger than for the total population of other insects.

Determination of natural enemies of H. cubana

Natural enemies of H. cubana found in L. leucocephala stands (Table 3) were grouped into 4 classes, 8 orders, 12 families and 21 genera. Several of those genera (Chilocorus, Cycloneda, Coleomegilla y Psyllaephagus) have been reported as biological control organisms for H. cubana (Lascano et al 1995; Gutiérrez y Geiger 2000).

The insect predators Diomus bruneri, Chrysoperla cubana, and Zelus longipes, fed on nymphs and adults of  H. cubana and were reported for the first time in Cuba. Female adults of the parasitoid insect Psyllaephagus sp. parasitize the 3^rd nymphal phase of H. cubana and emerge in the 5^th phase, the last nymphal instar, making this phase mummified and preventing the H. cubana adult from emerging. A species complex of arachnids consisting of Leucauge argyra, Peucetia viridians, and Misumenops bellulus, persisted in the agroecosystems withL. leucocephala. A complex of Formicidae, which fed on H. cubana nymphs and adults, included the species Pheidole megacephala, Tetramorium bicarinatum, and Dorymyrmex insularis, which have not previously been reported worldwide. Also, these species never have been reported to prey on H. cubana. Barrion et al (1987) in Philippines reported functional groups similar, in this case predators (species of ants and spiders) as natural control of H. cubana population in agroecosystems with L. leucocephala.

On the other hand, abundant and diverse predators associated with silvopastoral systems with leucaena-guinea are reported in Cuba (Alonso et al 2011, Valenciaga et al 2019) which contributes to keeping psyllid populations regulated under harmless levels.

Some microorganisms, including bacteria and fungus, are able to cause disease in H. cubana, mainly in adults. In this study it was detected the bacteria Bacillus spp. and the fungi Beauveria bassiana. Both microbial agents have been effective in controlling H. cubana populations (Liu et al 1990; Sajap et al 1995).

Fusarium, Cladosporium, Aspergillus and Penicillium were also isolated. However, Cladosporium, Aspergillus and Penicilium are known as saprophytic fungus (Leyva-Mir et al 2014), while Fusarium, despite being a phytopathogenic fungus, is also attributed the ability to infect insects (Pelizza et al 2011; Mosqueda-Anaya et al 2018).

Assignment of the functional groups

All organisms cited above as natural enemies of H. cubana, predators, parasitoids, pollinators and entomopathogens (Table 3) act as a complex in controlling H. cubana populations. In this case, the sirphid fly (adult) it classifies as pollinator but in larval phase it is a potent predator of nymphs and adults of leucaena psyllid.

The Figure 1 indicates when natural enemies are able to affect different phases of H. cubana’s life cycle. Most of the organisms associated with H. cubana act as bio-regulators of its population, controlling both nymphs and adults, except the parasitoid Psyllaephagus sp., which only affect nymphs at the 3^rd, 4^th and 5^th nymphal instar by preventing that they develop to the adult phase. No organisms were found that fed on H. cubana eggs or prevents them hatching.

Figure 1. Incidence of natural enemies of H. cubana in different phases of its biological cycle

Abundance of H. cubana in the different agroecosystems

H. cubana population density varies according to types of agroecosystems (Table 4). Leucaena-guinea stands (area 1 and 2) had the highest (P<0.001) (Duncan 1955). H. cubana population, likely related to their poor biodiversity of vegetable species.

H. cubana populations tend to reduce with years after establishment and with the increments on number of plant species present in the agroecosystems, but it was not statistically different (P>0.05) (Duncan 1955). Nevertheless, it could be expected as a result of the biological equilibrium that is achieved over time, which could be supported by the diversification of the agroecosystem (Valenciaga and Mora 2002; Alonso et al 2007). In agroecosystems where L. leucocephala is associated with other plant species, the H. cubana population is low, although it still dominates over other associated organism plant-eaters in the favorable period of prevalence (october - december). This could be the reason why the association with other crops contributes to reduce the H. cubana population within the environmental load.

The main component analysis of population density of H. cubana and the evaluated variables indicates that four components explain more than 75% of the variability in the incidence of H. cubana on leucaena-guinea agro-ecosystem (Table 5).

In area 1, 76.4% of variability was explained by the four components, and the corresponding values for each main component (MC) were 3.2, 1.8, 1.4 and 1.2. Minimum temperature, in both areas, was the factor that explained the most variability of H. cubana population density in MC1. Minimum, mean, and maximum temperatures were key factors in emergence and population density of H. cubana and, consequently, they have a significant impact on the environmental load the second factor. MC2, was dominated by total rainfall and rain days, which accounted for 97% of the variability. Spiders and coccinellids are denoted in the third main component (MC 3), which confirms the important role of natural enemies in H. cubana population control. Lastly, in the fourth component (MC 4), H. cubana population positively correlates with relative humidity

In area 2, 80.55% of variability was explained by the four components, and the corresponding values for each main component were 3.5, 1.8, 1.7 and 1.2. As was the case in area 1, temperature was the main factor affecting population density of H. cubana. These results are in agreement with the findings of Elder (2002) who indicated that temperature and relative humidity are the main factors that control H. cubana population. Elder (2002) also reports that H. cubana prefers temperatures above 20 ºC, which explain the population increase towards the end of the rainy season and at the beginning of the dry season, as described by Valenciaga et al (2005), who stated that during this period there are optimal conditions for H. cubana development.

As was the case in area 1, total rainfall and rain days accounted for 97% of the variability of MC 2. Coccinellids were the most important indicator for MC 3, of which four species were collected. In MC4, the H. cubana population was positively correlated with ants, of which several species were identified.

Assessing the results from both areas, climatic factors strongly influenced H. cubana population dynamics. This was stronger than the effect of the biotic factors, which did not strongly feature until the third component (MC 3), represented primarily by ants and spiders in area 1 and by coccinellids and spiders, to some extent, in area 2.

This explains the intense activity of H. cubana in the months where temperature (20 - 25 °C), relative humidity (80 to 90 %) and rainfall (abundant summer rains above 150 mm per month) favor the presence of the insect. Although climatic factors determine H. cubana emergence and population density, their interrelation with biotic factors lastly define population peak during the year (october - december). This highlights the importance of assessing the agro-ecosystem as a whole. Ahmed et al (2014) emphasize the regulatory role of the natural enemies of the leucaena psyllid (predators, parasitoids and entomopathogens) in its population dynamics. In addition, the use of resistant cultivars planted under favorable climatic conditions.

Based on the set of measurable factors in the agroecosystem in which H. cubana develops, it was possible to elaborate a diagram in which the essential factors that affect the population density are highlighted (Figure 2). This is a basic tool to maintain acceptable levels of insect population, and in cases of population explosion, to have methods and means for its control.

The criteria that must be met to keep H. cubana populations below non-harmful levels, for the conditions under study consists on carrying out periodic monitoring in areas of L. leucocephala, from the initial phenological stage of the crop (sowing - vegetative growth). This stage coincides with the establishment of the crop, fundamentally during the months of preference of the pest (september-january). Given the favorable climatic conditions of temperature (20-22°C) and humidity (80-90%) and during the emission of the new shoots, either stimulated by the pruning trees or browsing by animals, which increases the population density of H. cubana. In addition, plant biodiversity must be favored in the system (sowing temporary crops or association with other trees) that which allow the preservation and increase the natural enemies in agroecosystem areas. Obviously, a substantial increment in the population density of H. cubana reduces their population, due to the intra-specific competition that is established between organisms for the food and for their living space. However, the occurrence of other phytophagous insects it doesn't influence the incidence of the leucaena psyllid. This demonstrates that H. cubana is the only insect that inhabits and reproduces in the new shoots or growth points of this legume.

Figure 2. Graphic simulation of the factors that affect H. cubana emergence in L. leucocephala

Conclusions

It is concluded that despite the abundance shown by H. cubana, in the dry season, in areas of L. leucocephala, favored by the climatic conditions in the period. There is a permanence of natural enemies of the leucaena psyllid, under Cuban conditions, given by predators, parasitoids and entomopathogens that favor their control. It is recommended to favor or increase the presence of these natural enemies in the agroecosystem to prevent economic damage to the legume and to continue promoting the use of the tree as animal feed.

Acknowledgements

We appreciate the collaboration of Drs J.L. Fontenla and G. Alayon, both from the Museum of Natural History of Havana, in the identification of ants and spiders collected, respectively. As well as to Dra. Elayne Valiño, from the Institute of Animal Science (ICA), in the isolation and identification of pathogens detected as natural enemies of H. cubana. We are also grateful to Dra. Verena Torres and Aida C. Noda, both from ICA, for the statistical analysis of data.

References

Ahmed A M M, Ramírez-Avilés L, Solorio-Sánchez F J, Al-Zyoud F A and Barros-Rodriguez M 2014 An overview on some biotic and abiotic factors affecting the population dynamics of Leucaena psyllid, Heteropsylla cubana Crawford (Homoptera: Psyllidae): Contributory factors for pest management. Tropical and Subtropical Agroecosystems, 17, 437-446. https://www.redalyc.org/articulo.oa?id=939/93935728003

Alonso J, Valenciaga N, Arruda Sampaio R and Leão Demolin Leite G 2007 Zoological diversity associated to a silvopastoral system leycaena-guinea grass with different establishment times. Pesquisa Agropecuaria Brasileira 42, 1667- 1674. https://doi.org/10.1590/S0100-204X2007001200001

Alonso O, Lezcano J C and Suris Moraima 2011 Composición trófica de la comunidad insectil en dos agroecosistemas ganaderos con Leucaena leucocephala (Lam.) de Wit y Panicum maximum Jacq. Pastos y Forrajes 34, 433-444. http://scielo.sld.cu/scielo.php?script=sci_arttext&pid=S0864-03942011000400004

Barrion A T, Aguda R M, Litsinger J A and Barrion R 1987 The natural enemies and control of the leucaena psyllid, Heteropsylla cubana Crawford (Hom: Psyllidae), in the Philippines. Leucaena Research Reports 7, 45. https://books.google.com.cu/books?id=c4EqAQAAMAAJ&hl=es&source=gbs_book_other_versions

Bray R A and Woodroffe T D 1991 Effect of leucaena psyllid on yield of Leucaena leucocephala cv Cunningham in south-east Queensland. Tropical Grasslands 25, 356-357. http://www.tropicalgrasslands.info/public/journals/4/Historic/Tropical%20Grasslands%20Journal%20archive/PDFs/Vol_25_1991/Vol_25_04_91_pp356_357.pdf

Castillo E, Díaz A, Martín P C and Ruiz T E 2012 Utilización de Leucaena leucocephala para la producción de carne bovina. In: Ruiz T E, Febles G J and Lok S (Eds.) Experiencia en el manejo de Leucaena leucocephala para la producción animal en Cuba. Ediciones del Instituto de Ciencia Animal (EDICA), Mayabeque, Cuba. 154‒164.

Duncan D B 1955 Multiple Range and Multiple F Tests. Biometrics, 11, 1–42, ISSN: 0006-341X, DOI: 10.2307/3001478. http://www.jstor.org/stable/3001478?origin=JSTOR-pdf

Durán J L and Pérez J M 1994 Correlación de la Clasificación Genética con otros sistemas de clasificación. Ponencia ante la Primera Conferencia de Clasificación de los suelos. La Habana, Cuba. 21.

Elder R 2002 Leucaena psyllid in Leucaena. The Bugwood Network and USDA Forest Service. The University of Georgia. Warnell School of Forest Resources and College of Agricultural and Environmental Sciences. Dept. of Entomology. http://www.fao.org/edu/re/index.html

Fernández B M 1995 Papel de los biorreguladores y algunos factores climáticos en la población de unaspis citri C. (Homoptera: Diaspididae). Parte II. Revista Protección Vegetal 10, 85.

Finlay-Doney M and Walter G H 2005 Discrimination among host plants (Leucaena species and accessions) by the psyllid pest Heteropsylla cubana and implications for understanding resistance. Agricultural and Forest Entomology 7, 153.

Galindo J 2001 Fermentación microbiana ruminal y pasaje hacia las partes bajas del tracto gasto-intestinal de árboles y arbustos de leguminosas. In: Memorias del curso “Sistemas Silvopastoriles, una opción sustentable”. Centro de Desarrollo Tecnológico Tantakín. 131.

Gutierrez A P and Geiger C A 2000 Ecology of Heteropsylla cubana (Homoptera: Psyllidae): psyllid damage, tree phenology, thermal relations, and parasitism in the field. Environmental Entomology 29, 76.  https://bioone.org/journals/Environmental-Entomology/volume-29/issue-1/0046-225X-29.1.76/Ecology-of-Heteropsylla-cubana-Homoptera--Psyllidae--Psyllid-Damage/10.1603/0046-225X-29.1.76.short.

Hernández A, Pérez J, Bosch D and Castro N 2015 Clasificación de los suelos de Cuba Editorial Ediciones INCA, Mayabeque, Cuba. 93. ISBN: 978-959-7023-77-7. http://ediciones.inca.edu.cu/files/libros/clasificacionsueloscuba_%202015.pdf

Hodkinson I D and White I M 1979 Homoptera: Psylloidea. Handbooks for the identification of British Insects. 2, 1-98.

Jordán H 2000 Estudio de la tecnología de producción de las vacas Holstein para solucionar el déficit de biomasa a partir de leguminosas. PNCT. Informe Final. CITMA. La Habana, Cuba.

Jordán H 2012 Los sistemas silvopastoriles para la hembra de reemplazo y producción de leche en bovinos. In: Ruiz T E; Febles G J and Lok S (Eds.) Experiencia en el manejo de Leucaena leucocephala para la producción animal en Cuba. Ediciones del Instituto de Ciencia Animal (EDICA), Mayabeque, Cuba. 132‒153.

Lascano C E, Maas B L, Argel P J and Víquez E 1995 Leucaena in Central and South America. In: H.M. Shelton; C.M. Piggin and J.L. Brewbaker (Eds.). Leucaena opportunities and limitations. Proceeding of workshop held in Bogor, Indonesia. 24-29 January 1994. ACIAR Canberra, Australia. Proceedings N° 57, 152-158. bit.ly/2UphJVM

Leyva-Mir S G, Cervantes-García M A, Villaseñor-Mir H E, Rodríguez-García María Florencia, García-León Elizabeth and Tovar-Pedraza J M 2014 Diversidad de hongos en semilla de avena del Valle Central de México Revista Mexicana de Ciencias Agrícolas Pub. Esp. 8, 1379-1385. http://www.scielo.org.mx/pdf/remexca/v5nspe8/2007-0934-remexca-5-spe8-1379-en.pdf

Liu S D, Chang Y C and Huang Y S 1990 Application of entomopathogenic fungi as biological control of Leucaena psyllid, Heteropsylla cubana Crawford (Homoptera: Psyllidae) in Taiwan. Plant Protection Bulletin Taipei 32, 49–58. ISSN: 0577-750X. https://www.cabdirect.org/cabdirect/abstract/19921159687

Mancina C A and Cruz D D 2017 Diversidad biológica de Cuba: métodos de inventario, monitoreo y colecciones biológicas. Editorial AMA, La Habana, 480. ISBN: 978-959-300-130-4 (versión digital). https://www.undp.org/content/dam/rblac/docs/Research%20and%20Publications/Repository/Cuba/UNDP-RBLAC-DiversidadBiol%c3%b3gicaCU.pdf

Mangoendihardjo S, Wagiman F X, Trisyono Y A and Sujuno M 1990 Seasonal abundance of Leucaena psyllid populations in Yogyakarta, Indonesia. In: B Napompeth and K.G. Mac Dicken (Eds). Leucaena Psyllid: Problem and management. Proceeding of on International Workshop held in Bogor, Indonesia. January 16-21 1989 Winrock International/IDRC/ NFTA. 111-113.

Mendoza F 1988 Sistemática de Insectos. Segunda parte. Editorial Pueblo y Educación. La Habana, Cuba. 134.

Metcalf C L and Flint W P 1965 Insectos destructivos e insectos útiles: sus costumbres y su control. Instituto Cubano del Libro. La Habana, Cuba, 1208.

Milera Milagros 2013 Contribución de los sistemas silvopastoriles en la producción y el medio ambiente. Avances en Investigación Agropecuaria, 17, 7-24. ISSN: 0188-7890. https://www.redalyc.org/articulo.oa?id=837/83728497002

Milera Milagros, Iglesias J, Remy V and Cabrera N 1994 Empleo del banco de proteína de Leucaena leucocephala cv. Perú para la producción de leche. Pastos y Forrajes 17, 73.

Mohammed A H M, Aguilar C F, Ayala J, Bottini M B, Solo F J and Ku J C 2015 Evaluation of milk composition and fresh soft cheese from an intensive silvopastoral system in the tropics. Dairy Science Technology 96, 159–172. https://doi.org/10.1007/s13594-015-0251-4.

Mosqueda-Anaya J A, Landeros-Jaime F, Ramírez-Baltazar S, Santiago-Basilio M A, Vergara-Pineda S, Cervantes-Chávez J A and Esquivel-Naranjo E U 2018 Hongos asociados a cadáveres de insectos plaga en el estado de Querétaro, México Scientia Fungorum 47, 25-35. http://www.scielo.org.mx/pdf/sf/v47/2594-1321-sf-47-25.pdf

Muddiman S B, Hodkinson I D and Hollis D 1992 Legume-feeding psyllids of the genus Heteropsylla (Homoptera: Psylloidea). Bulletin of Entomological Research 82, 73-117.

Pelizza S A, Stenglein S A, Cabello M N, Dinolfo M I and Lange C E 2011 First record of Fusarium verticillioides as an entomopathogenic fungus of grasshoppers. Journal of Insect Science, 11, 70 https://doi.org/10.1673/031.011.7001

Quevedo R I 1993 Metodología para el estudio de fincas. Aproximación multivariada. Revista Facultad de Agronomía Univesidad Central de Venezuela. 258.

Rivera-Herrera J, Isabel Molina, Chará J, Murgueitio E and Barahona R 2017 Sistemas silvopastoriles intensivos con Leucaena leucocephala (Lam.) de Wit: alternativa productiva en el trópico ante el cambio climático. Pastos y Forrajes 40, 171–183. https://payfo.ihatuey.cu/index.php?journal=pasto&page=article&op=view&path%5B%5D=

Ruiz T E and Febles G 1999 Sistemas silvopastoriles: conceptos y tecnologías desarrolladas en el Instituto de Ciencia Animal de Cuba. La Habana EDICA, 34.

Ruiz T E, Febles G J, Castillo E, Simón L, Lamela L, Hernández I, Jordán H, Galindo J L, Chongo Bertha B, Delgado Denia C, Crespo G J, Valenciaga Nurys, La O O, Alonso J, Cino Delia M, Lok Sandra, Reyes F, Esperance M, Iglesias J, Hernández Marta, Sánchez Tania, Pérez A and Soca Mildrey 2019 Leucaena feeding systems in Cuba. Tropical Grasslands 7, 403–406 https://doi.org/10.17138/TGFT(7)403-406.

Sajap A S, Soong S K and Mashita M 1995 Susceptibility of leucaena psyllid, Heteropsylla cubana (Hom:Psyllidae) to Beauveria bassiana and Paecilomyces fumosoroseus (Deuteromycotina). Kuala Lumpur, Malaysia.176-178.

Schultze-Kraft R 1994 El Psyllid de Leucaena también puede ser un problema en América Tropical. Pasturas tropicales. CIAT. 16, 48.

Shelton M 2017 Seven decades of leucaena in Australia: What we have achieved. In: Chará, J, Peri P, Rivera J, Murgueitio E, Castaño K. (Eds.). Sistemas Silvopastoriles: Aportes a los Objetivos de Desarrollo Sostenible. CIPAV. Cali, Colombia. Fundación CIPAV. 367-377. http://www.cipav.org.co/pdf/Manizales18/Capitulo%204.pdf#Capitulo%204.indd:4

Snedecor G W and Cochran W F 1969 Statistical methods. 6th Ed. The IOWA State University Press Ames, IOWA. USA. 15-243.

Torres V, Martínez R O and Noda A 1993 Example of application of technical multivariadas in different stages of the evaluation process and selection of species of grasses. I. Main Components. Cuban Journal Agricultural Science 27, 131.

Triplehorn C A and Johnson N F 2005 Borror and DeLong's lntroduction to the Study of lnsects. Thomson Brooks/Cole, USA, 864, Seventh Edition, ISBN 003-096835-6. https://www.academia.edu/30669150/Borror_and_Delong_2005_Study_of_Insects

Valenciaga N and Mora C 2002 Study on the population of insects in a Leucaena leucocephala (Lam) de Wit area with different tree combinations under grazing conditions. Cuban Journal Agricultural Science 36, 293-299.

Valenciaga N, Flores L, Martínez-Machín L and Mora C 2005 Space and time dynamics of Heteropsylla cubana in sowings of Leucaena leucocephala. Cuban Journal Agricultural Science 39:223-231. NValenciaga-39-2-2005-DynamicHcubana-Ingls.pdf

Valenciaga N, Herrera M and Ruiz T E 2019 Capítulo 8. Heteropsylla cubana Crawford (Hemiptera: Psyllidae) en sistemas silvopastoriles con Leucaena leucocephala (Lam.) de Wit (Fabaceae) en condiciones de Cuba. 206-223. En: Karen Castaño-Quintana, J Chará, Carolina Giraldo, Zoraida Calle (Eds.). Manejo Integrado de Insectos Herbívoros en Sistemas ganaderos Sostenibles. ISBN 978-958-9386-93-4 Digital, CIPAV, Cali Colombia, 306. http://www.cipav.org.co/InsectHerb/descargar.php

Valenciaga N, Herrera M, Mora C and Noda A 2010 Assessment and determination of infestation levels of phytophagous insects in a leucaena-guinea grass agro-ecosystem. Cuban Journal Agricultural Science 44, 309-315. http://www.cjascience.com/index.php/CJAS/article/view/227

World Spider Catalog 2020 World Spider Catalog.Version 21.5. Natural History Museum Bern, online at http://wsc.nmbe.ch https://doi.org/10.24436/2

Zayas F De 1988 Entomofauna cubana. Tomo VII. Editorial Científico- Técnica. La Habana, Cuba. 85-137.