BIoecology of Oncideres cervina Thomson (Coleoptera: Cerambycidae) on Persea americana Mill. (Lauraceae)

Abstract Cerambycidae beetles limit production and establishment of forest and fruit trees. Oncideres cervina Thomson, 1868 (Coleoptera: Cerambycidae) is one of the most important species. The objective was to record O. cervina girdling branches of Persea americana Mill. (Lauraceae) for the first time, check the number of oviposition incisions (Noi) as a function of the diameter of branch sections, period of emergence, and describe the larval-pupal chamber. Individuals of O. cervina were observed, for the first time, in P. americana orchards in Santa Maria, Rio Grande do Sul, Brazil. The middle section of branches (40-60 cm interval) had higher number of incisions. Girdled branches with a diameter of 40-50 mm had higher number of them. Adults emerged from November through January. Larval-pupal boreholes had diameters between 9 and 11 mm, and average tunnel length was 28 mm, with a mean volume of consumed wood of 4.3 mL. This information is useful for establishing integrated pest management practices against O. cervina in P. americana since this crop has a high added value and can be significantly compromised by attack by Cerambycidae beetles.


Introduction
Lauraceae plants are good for reforestation projects, production of fruits, oils, and spices (Marques, 2001).The production of avocado (Persea americana Mill.(Lauraceae) in Brazil is around 15.8 tons.ha - , generating, on average, R$ 15,862.00.ha -1 on revenue (IBGE, 2019).The avocados are used mainly for the production of candies, cosmetics, oil from pulp, and in natura consumption (Salgado et al., 2008).100 cm.Each section represents a specific position on the branch, starting from the base where it attaches to the trunk (0-20 cm) and ending at the top (80-100 cm).The number of oviposition incisions (Noi -a opening made by a female to deposit her eggs in the branches) were counted for each section, and branch diameter was measured, at 1 cm from the girdling, with a caliper.Branch length was measured using a soft tape measure.

Period of emergence and larval-pupal chamber
We observed the branches stored in the laboratory every two weeks to determine adult specimens of O. cervina.After emergence of the adults, the length and diameter of the larval-pupal galleries were measured using a caliper.The galleries were filled with fine sand to determine the volume of wood consumed by measuring the sand volume in a graduated volumetric cylinder.

Statistical analysis
Descriptive statistics were done for data for Noi and branch diameter including means, minimum, maximum, standard error and deviation, sample variance, and coefficient of variation.
Diameter x Branch sections.The interaction between branch section and diameter was tested using a completely random design (CRD) with 5 treatments with 37 repetitions (branches).The treatments were the classes of branch length: T1: 0-20; T2: 20-40; T3:40-60 and T4: 80-100 cm.To evaluate the effect of branch section and diameter, the data were analyzed using a linear model.The quality of the model fit was graphically evaluated using a halfnormal-plot with simulation envelopes at a level of 95%, using the 'hnp()' function from the 'hnp' package in the R software (Moral et al., 2017).Subsequently, the model was submitted to an analysis of variance (ANOVA), and the means comparison between branch sections was conducted using a Tukey post hoc test.
Noi x branch section.To test for the effect of branch section on Noi, a CRD with 5 treatments with 37 repetitions.The treatments were the classes of branch length: T1: 0-20; T2: 20-40; T3:40-60 and T4: 80-100 cm.To evaluate the effect of branch section (treatment) on the concentration of Noi, a general linear model was used (GLM), with a negative binomial error distribution using the function 'glm.nb()' from the 'MASS' package (Venables and Ripley, 2002).The fit of the model was graphically evaluated using a half-normal-plot with simulation envelopes at a level of 95%, using the 'hnp()' function from the 'hnp' package (Moral et al., 2017).Subsequently, the model was submitted to an analysis of variance (ANOVA), and the means comparison between branch sections was conducted using a Tukey post hoc test.
Noi x branch diameter.The relationship between Noi and branch diameter was analyzed using a quadratic GLM with a negative binomial error distribution.In this test, Noi was set as a response variable as a function of branch diameter.The quality of the model fit was graphically evaluated using a half-normal-plot with simulation envelopes at a level of 95%, using the 'hnp()' function from the 'hnp' package (Moral et al., 2017).The model was twig girdlers in the Americas (Vulcano and Pereira, 1978;Paro et al., 2011).The Oncideres females girdle fresh and healthy branches of trees where they lay their eggs.This occurs due to the need for larvae to feed on branches that are in the beginning of the decomposition process (with high humidity and still soft tissues), to complete their development cycle (Baucke, 1962;Coppedge, 2011;Witeck Neto et al., 2015).
The girdling damage limits the establishment of monoculture plantations of forest and fruit tree species, like Acacia mearnsii De Wild, Ocotea puberula (Rich.)Nees and Pyrus pyrifolia (Burm F.) Nakai.(Witeck Neto and Link, 1997;Cordeiro et al., 2010;Lemes et al., 2011;Magistrali et al., 2013;Witeck Neto et al., 2013).These insects may also cause indirect damage due to morphological alterations of their hosts, such as creation of forks in the trunk and an accumulation of nitrogen in branches.These damage may result in depreciation of the commercial value of wood and reduce fruit productivity (Calderón-Cortés et al., 2011;Witeck Neto et al., 2013;Coppedge, 2014).
The characterization of the larval-pupal galleries left by the larvae of Cerambycidae after adult emergence is an important tool to evaluate questions related to adaptation cost, feeding behavior, and morphometric aspects of the emerged adults (Link et al., 1994;Witeck Neto et al., 2015;Corrêa et al., 2024).With respect to wood consumption by the larvae, the length and volume of the galleries were measured, and these parameters are related to host adaptability.
Oncideres cervina Thomson, 1868 (Coleoptera: Cerambycidae) is an insect pest capable of causing damage to species from different families (i.e.Lauraceae and Thymelaeaceae) (Paro et al., 2011;Witeck Neto et al., 2015).However, their records in host plants are still scarce, a factor that can complicate their management.
Describe the occurrence and bioecology of twig girdlers in new hosts is important to verify population density, damage prediction, and elaborate integrated pest management strategies (Witeck Neto et al., 2015;Corrêa et al., 2022).The objective of this study was to record the occurrence of O. cervina on branches of P. americana, for the first time, and to investigate biological parameters in this host.

Study area
Branches girdled by twig girdlers were collected from a 40 ha P. americana orchard in Santa Maria, Rio Grande do Sul, Brazil, from November 2011 to January 2012.This area is part of the Central Depression physiographic region (29°41'24"S, 53°48'42"W), and its climate is humid subtropical without a dry season (Cfa), according to the Köppen climate (Valério et al., 2018).The collected branches were stored in plastic boxes covered with voile cloth to determine adult emergence.

Branch diameter and number of oviposition incisions (Noi)
The branches were split into five sections, each measuring 20 cm long, making a total branch length of subsequently submitted to deviance analysis to verify the significance of the observed tendencies.

Descriptive statistics
The mean number of oviposition incisions was 3.13.branch -1 , with a coefficient of variation of 119%, and amplitude from 0 to 24.Mean branch diameter was 44.4 mm, with a coefficient of variation of 30.6%, and amplitude from 15 to 80 mm.

Period of emergence and larval-pupal chambers
The greatest number of O. cervina adults emerged during the second half of November, reducing at the start of December, and ceased by the second half of January (Figure 1).
The boreholes were between 9.53 to 11.02 mm, with the largest axis having an amplitude between 6.7 and 15.3 mm, and the smallest between 5.0 and 12.7 mm.The mean length was 28.07 mm, and the volume was 4.31 mL.The coefficient of variation for the volume was large, indicating a high proportion of variation in the values of wood consumption between larval-pupal galleries in relation to the mean value (Table 1).

Effect of branch diameter on Noi
The analysis of deviance for the GLM indicated significant effects for the linear ( 1x β ) and quadratic ( 2 ² x β ) components of branch diameter on mean Noi ( 1x β : x 2 = 11.70;df = 1; p < 0.001; 1 ² x β : x 2 = 11.66;df = 1; p < 0.001).The GLM indicated a rate increase (log) of 0.097 for mean Noi as a function of branch diameter up to approximately 45 mm.For branches larger than 45 mm, the GLM estimated a rate decrease (log) of -0.001 for Noi (Figure 3).

Period of emergence and characterization of larval-pupal galleries
The season of adult emergence is of great importance to predictive models based on time series, which are useful for implementation of strategies for Integrated Pest Management (IPM).Predicting periods of greater occurrence of this pest helps to intensify monitoring and decision-making for control.Adults emerged during November through January, with the largest emergence during the second half of November.In southern Brazil, twig girdlers beetles of the Oncideres genus emerge between October and May, a period corresponding to that observed in the present study (Witeck Neto and Link, 1997;Witeck Neto et al., 2013;Witeck Neto et al., 2015).For larval-pupal galleries length, the results from this study (28 mm) were inferior to those for O. cervina on of O. puberula (53.7 mm) (Witeck Neto et al., 2015)¸ indicating a lower rate of consumption on P. americana.This result could be related to the physical structure of the branches and wood density, factors than can influence the rate of larval wood consumption (Coppedge, 2011;Brown et al., 2016).
The volume of wood consumed indicates the nutritional adaptability of the host (Forcella, 1984;Costa and Marques, 1988;Witeck Neto et al., 2015).In this case, O. cervina that occur on P. americana tend to have a lower rate of assimilation, and consequently a greater necessity to consume wood to support their development, compared to other species of Lauraceae, such as O. puberula as related by Witeck Neto et al. (2015).
The dimensions reported for O. cervina on O. puberula (Witeck Neto et al., 2015), show that, in the current study, the boreholes made in P. americana were larger and had a lower coefficient of variation, suggesting emergence of larger adults and with lower variability between individuals.This variation indicates and effect of the botanical species not only on aspects related to oviposition behavior, wood consumption, and larval viability, but also on the final size of the emerged adults.

Effect of branch section and diameter on Noi
Our results suggest a preferential zone for oviposition by O. cervina in the middle section (40-60 cm).Similarly, the GLM model estimated greater Noi between diameters of 40 and 50 mm, with a peak around 45 mm (Figure 2), corroborating the data on the preferential zone for oviposition.Witeck Neto et al. (2015) also reported a larger value for Noi by O. cervina in the middle section of branches (80-100 cm) of Ocotea puberula (Rich.)Nees, in Santa Maria, Rio Grande do Sul, Brazil.The mean Noi found in branches of O. puberula (13.10) by Witeck Neto et al. (2015) was greater than that for the current study of P. americana (4.00), indicating a possible effect of speciesspecific characteristics (i.e., wood chemical composition, density, and nutrient availability).
The preference for a specific section of a branch for oviposition may be related to the wood density and availability of nutrients (Rice, 1989).In the current study, the mean diameter of the basal section of branches (0-20 cm) was greater than the mean diameter of the final section of the branch (80-100 cm).
Besides these factors, another aspect that may contribute to a preference for the middles section of branches for oviposition by O. cervina, is the rate at which the branch dries out.At the base and apical sections, the rate of drying is greater than the other sections, which makes larval development difficult (Diodato et al., 1997).Therefore, these two extremities do not have favorable conditions for oviposition, and they are avoided in favor of the middle section of the branch.This result agrees with that from Lemes et al. (2014), where there was greater Noi in branches with diameters that were between the thinner and thicker sections of the branch, which could be related to the combination of girdling ability of females and the necessity to provide resources to the larvae.

Conclusions
The current study reports the first occurrence of O. cervina on branches of the P. americana.The results presented and discussed in this research are of great importance for the organization of monitoring plans for insect pests and creation of strategies for integrated pest management for P. americana, which now should consider O. cervina.
The emergence of adults of O. cervina on P. americana occurred between November and January, with a peak of emergence during the second half of November.
Parameters related to the dimensions of larval-pupal galleries suggest a necessity for a greater consumption of P. americana wood compared to other species of Lauraceae.The dimensions of the boreholes indicate a larger size of adults emerging from P. americana, while the length of larval-pupal galleries in P. americana was smaller than other Lauraceae species.
Branches of P. americana with a diameter of approximately 45 mm (middle section of a 1m branch) represent the preferential zone for oviposition by O. cervina.