Arthropods as possible loss or solution sources on Acacia mangium (Fabales: Fabaceae) saplings

Abstract Acacia mangium (Willd.) (Fabales: Fabaceae) tree shows applicability in programs to recover degraded areas due to its fast-growing, rustic, pioneer species, with the potential to fix nitrogen. However, this plant is attacked by pests. It is important to know, among them, the most important. This study aims to evaluate the herbivorous insects (loss sources) and their natural enemies (solution sources) on 48 A. mangium saplings. They were classified according to their ability to damage or reduce the source of damage on these saplings using the percentage of the Importance Index-Production Unknown (% I.I.-P.U.). The loss sources Trigona spinipes Fabr. (Hymenoptera: Apidae), Aleyrodidae (Hemiptera), Phenacoccus sp. (Hemiptera: Pseudococcidae), Aethalion reticulatum L. (Hemiptera: Aethalionidae), and Tropidacris collaris Stoll. (Orthoptera: Romaleidae), showed the highest % I.I.-P.U. on leaves of A. mangium saplings. The solution sources Oxyopidae (Araneae), Pseudomyrmex termitarius (Smith) (Hymenoptera: Formicidae), and Brachymyrmex sp. (Hymenoptera: Formicidae), showed the highest % I.I.-P.U. on leaves of A. mangium saplings. The number of Lordops sp. (Coleoptera: Curculionidae) was reduced per number of Brachymyrmex sp.; that of T. collaris those of Oxyopidae and Brachymyrmex sp.; and that of Tettigoniidae that of P. termitarius, totaling 8.93% of reduction of these herbivorous insects (numbers) on A. mangium saplings. These herbivorous insects turn into problems in commercial plantations of this plant since to are related to pests in some crops. These tending ants and Oxyopidae can be important on A. mangium commercial crops because they can reduce the number of these herbivorous insects.


Introduction
Acacia mangium (Willd.)(Fabales: Fabaceae) tree is a fast-growing, rustic pioneer species with potential for nitrification due to symbiosis with diazotrophic bacteria, resulting in high litter production (Caldeira et al., 2018; September of this year.Each A. mangium seedling was planted in a hole (40 x 40 x 40 cm) when they reached 30 cm high with a 2-meter spacing between them.The soil was corrected with dolomitic limestone with the base saturation increased to 50%, natural phosphate, gypsum, FTE (Fried Trace Elements), potassium chloride, and micronutrients based on the soil analysis.A single, 20 L dose of dehydrated sewage sludge with defined biochemical characteristics (Silva et al., 2020) was placed per hole.The young 48 A. mangium saplings (young trees in the vegetative period) were irrigated twice a week until the beginning of the rainy season (October).

Counting the arthropods
The percentage of defoliation (leaf area loss) on a 0-100% scale with 5% increments for removed leaf area (Kogan and Turnipseed, 1980), and damage score from sap-sucking insects: I = non-damage; II = appearance of yellow chlorotic spots (leaf with 1% to 25% of attack symptoms); III = some yellow chlorotic spots and/or start of black sooty mold (leaf with 26% to 50% of attack symptoms); IV = several yellow chlorotic spots and/or severe blackening of leaves (leaf with 51% to 75% of attack symptoms); and V = yellowing or complete leaf drying (leaf with 76% to 100% of attack symptoms) (Demolin-Leite, 2024a), were assessed visually, and all insects and spiders were counted, between 7:00 A.M. and 11:00 A.M., by visual observation, every two weeks on the adaxial and abaxial surfaces of the first 12 leaves expanded, per sapling [sampling unit (n) -one leaf].Leaves were randomly assessed on the branch (one leaf per position) in the basal, middle, and apical parts of the canopy -vertical axis -(0 to 33%, 34 to 66%, and 67 to 100% of total sapling height, respectively) and in the north, south, east, and west directions -horizontal axis.A total of 12 leaves/sapling/evaluation were observed on 48 A. mangium saplings (age = 12 months) starting six months after transplantation for 24 months (27,648 total leaves), covering the entire sapling (vertical and horizontal axis), capturing the highest possible number of arthropods (insects and spiders), especially the rarest ones.In these saplings, the number of arthropods on the trunks was also assessed for each evaluation.The evaluator carefully approached, firstly assessing the adaxial leaf surface and, if it was not possible to visualize the abaxial one, with a delicate and slow movement, the leaf was lifted and visualized.The position of leaves of A. mangium saplings is generally tilted upwards, facilitating the visual assessment of arthropods on their leaf surfaces.Insects with greater mobility (e.g., Orthoptera), that flew on approach, were counted as they were recognized (e.g., Order).The arthropods (insects and spiders) were not removed from the saplings during the evaluation.
A few arthropod specimens (up to 3 individuals) per species were collected with an aspirator (two hours per week), at the beginning of the study (between transplantation and first evaluation), stored in flasks with 70% alcohol, separated into morph species, and sent to specialists for identification (see acknowledgments).Any visible arthropod, not yet computed in previous Eloy et al., 2018;Paula et al., 2018).Acacia mangium is adapted to acidic and infertile soils makes this plant important for recovering degraded areas (Balieiro et al., 2004;Wang et al., 2013).Besides, its wood is used, for example, in the construction of furniture (Hegde et al., 2013).However, this plant is attacked by different insect groups: sap-sucking, defoliators, stem apex chewing, and the wood-borer (Lemes et al., 2013;Parreira et al., 2014;Silva et al., 2015Silva et al., , 2020)).On the other hand, A. mangium is visited and/or colonized by several predators such as ants, neuropteran, spiders, wasps, and others (Silva et al., 2020;Gomes et al., 2023;Lima et al., 2024).These arthropods can be loss and solution sources on A. mangium saplings.It is important to know, among them, the most important in each group.
The Importance Indice (I.I.) can determine the loss and solution sources on a system in some knowledge areas (e.g., agronomy), when production is known (Demolin- Leite, 2021).Events (e.g., agricultural pest) can present different magnitudes (numerical measurements), frequencies, and distributions (aggregate, random, or regular) of event occurrence, and I.I. bases in this triplet (Demolin- Leite, 2021).In general, the higher the magnitude and frequency, with aggregated distribution, the greater the problem or solution (e.g., natural enemies versus pests) for the system (Demolin- Leite, 2021).However, the final production of the system is not always known or is difficult to determine (e.g., degraded area recovery).A derivation of the I.I. is the percentage of Importance Index-Production Unknown (% I.I.-P.U.) that can detect the loss or solution sources, when production is unknown, for the system (Demolin- Leite, 2024a).
The objective of this study was to determine the loss (e.g., herbivores insects) and solution (e.g., natural enemies) sources, classifying them according to their importance regarding their ability to damage or mitigate the source of damage on 48 A. mangium saplings -system with production unknown.

Experimental site
This study was carried out in a degraded area (≈ 1 ha) of the "Instituto de Ciências Agrárias da Universidade Federal de Minas Gerais (ICA/UFMG)" in the city of Montes Claros, Minas Gerais state, Brazil (latitude 16º 51' 38" S, longitude 44º 55' 00" W, altitude 943 m) for 24 months (April 2015 to March 2017).According to the Köppen climate classification, the climate of this area is tropical dry, with annual precipitation and temperature between 1,000 and 1,300 mm and ≥ 24ºC, respectively (Alvares et al., 2013).The soil is Neosol Litolic with an Alic horizon (Silva et al., 2020).

Experimental design
The A. mangium seedlings were prepared, in March 2014, in a nursery in plastic bags (16 x 24 cm) with reactive natural phosphate mixed with the substrate at a dosage of 160g and planted at the same time, in the final site in evaluations, was collected, coded, and sent to a taxonomist of each group (e.g., family).
The definition of what is a loss source or solution source was made by field observation (e.g., leaf damage), feed habits, and literature.The same was applied, as example, for prey-predator and sap-sucking insects-tending ant relationships.

Statistical analysis
Each replication is a sapling with the total individuals collected on 12 leaves (three heights and four sides of the sapling) for 24 months.The distribution type (aggregated, random, or regular) for the lost source (L.S.) or solution source (S.S.) was defined by the Chi-square test using the R-package 'IIProductionUnknown' (Demolin-Leite and Azevedo, 2022) (Supplementary materials I and II).The data were subjected to simple regression analysis and their parameters were all significant (P< 0.05) using the R-package 'IIProductionUnknown' (Demolin-Leite and Azevedo, 2022) (Supplementary material III).Simple equations were selected by observing the criteria: i) data distribution in the figures (linear or quadratic response), ii) the parameters used in these regressions were the most significant ones (P< 0.05), iii) P< 0.05 and F of the Analysis of Variance of these regressions, and iv) the coefficient of determination of these equations (R 2 ).Only L.S. and S.S. with P< 0.05 were shown in Supplementary Materials (I-III).All the data above were used in the Percentage of Importance Index-Production Unknown (% I.I.-P.U.).
Where: i) the key source (ks) is: ks = damage (non-percentage) (Da.)/total n of the L.S. on the samples or ks = reduction of the total n. of L.S. (R.L.S)/total n. of the S.S on the samples (Demolin-Leite, 2024a).Where Da. or R.L.S. = R 2 x (1 -P), when it is of the first degree, or ((R 2 x (1 -P))x(β 2 /β 1 ), when it is of the second degree, where R 2 = determination coefficient and P = significance of ANOVA, β 1 = regression coefficient, and β 2 = regression coefficient (variable 2 ), of the simple regression equation of the loss source (L.S.) or solution source (S.S.) (Demolin-Leite, 2024a).When it is not possible to separate the Da. between two or more L.S., divide the Da.among the L.S. as a proportion of their respective "total n".Da. = 0 when Da. was non-significant for damage or non-detected by L.S. on the system (Demolin- Leite, 2024a).When an S.S. operates in more than one L.S., that caused damage, its ks are summed.R.L.S. = 0 when Da. by L.S. or R.L.S. was non-significant for damage by L.S. or reduced L.S. by S.S. on the system (Demolin-Leite, 2024a).ii) c (constancy) = Σ of occurrence of L.S. or S.S. on samples, where absence = 0 or presence = 1 (Demolin-Leite, 2021).iii) ds (distribution source) = 1 -P of the chi-square test of L.S. or S.S. on the samples (Demolin-Leite, 2021).Counts (non-frequency) of L.S. or S.S. are used to perform the chi-square test.These data, above, are obtained, by R-package 'IIProductionUnknown' (Demolin- Leite and Azevedo, 2022).

Conclusions
The loss sources T. spinipes, Aleyrodidae, Phenacoccus sp., A. reticulatum, and T. collaris, showed the highest % I.I.-P.U. on leaves of A. mangium saplings.These insects turn into problems in commercial plantations of this plant since to are related to pests in some crops.The solution sources Oxyopidae, P. termitarius, and Brachymyrmex sp., showed the highest % I.I.-P.U. on leaves of A. mangium saplings.These natural enemies can be important on A. mangium due to their capacity to reduce herbivorous damages (e.g., Oxyopidae versus T. collaris) reducing 9% of herbivorous insects on A. mangium sapling.
I.I.-P.U.= ks x c x ds.ks = Da./totaln of the L.S.. Da. = R 2 x (1 -P) when it is of the first degree, or ((R 2 x (1 -P))x(β 2 /β 1 ) when it is of the second degree, where R 2 = determination coefficient and P = significance of ANOVA, β 1 = regression coefficient, and β 2 = regression coefficient (variable 2 ), of the simple regression equation, or non-percentage of damage per L.S.. c = Σ of occurrence of L.S. on each sample, 0 = absence or 1 = presence.ds = 1 -P of chi-square test of the L.S.. Da. = 0 when Da. non-significant for damage or non-detected by L.S..
I.I.-P.U.= ks x c x ds.ks = R.L.S./total n. of the S.S.. R.L.S.= R 2 x (1 -P) when it is of the first degree, or ((R 2 x (1 -P))x(β 2 /β 1 ) when it is of the second degree, where R 2 = determination coefficient and P