In the state of Guerrero, 4.3 million hectares of forest ecosystems have been documented (67 % of the state territory), 1.9 million (30 %) are temperate forests prone to attack by borer insects, defoliators, bark beetles, parasitic plants and some diseases (^{Consejo Civil Mexicano para la Silvicultura Sostenible A. C., 2008}). In the case of borers, the affected area until 2020 was only 45.69 hectares (^{Conafor, 2021}). These organisms include many Lepidoptera and Coleoptera species that are economically important to many forest species, particularly pines. In regard to harmful Lepidoptera, Tortricids included in the Apolychrosis (Amsel, 1962), Choristoneura (Lederer, 1859), Eucosma (Hübner, 1823), Retinia (Guenée, 1845) and Rhyacionia (Hübner, 1825) genera (Lepidoptera: Tortricidae) are mentioned; likewise, species such as Synanthedon cardinalis (Dampf, 1930) (Lepidoptera: Sessidae) have been recorded only for some Mexican states, although ^{Cibrián et al. (1995)} do not give them economic significance.

In the aforementioned entity, the borer species have not been fully identified. Likewise, the estimate of their damages has not been documented either, despite the relevance of the pines in the communities of La Montaña region, where its inhabitants use their wood for house building and fuel, in addition to the fact that its commercialization they obtain an economic income that contributes to family finances.

In Plan de Guadalupe community, at Atlamajalcingo del Monte municipality, Guerrero, Mexico larvae of an insect have been observed that damage pine trees, which present withering and some of them become standing-dead; this situation has disturbed the residents of the town, because they are losing vegetation cover. Therefore, the objective of this work was to identify the insect that causes damage to pine trees, as well as to assess the infestation degree in forest fragments of the community under study.

Plan de Guadalupe belongs to the La Montaña region; It is located at 2 050 masl, between 17°10' and 17°21' N, 98°30' and 98°39' W; it is bordered to the north by Malinaltepec, Copanatoyac and Xalpatláhuac municipalities, to the east by Xalpatláhuac and Metlatónoc, to the south by Metlatónoc and Malinaltepec, and to the west by Malinaltepec and Copanatoyac (^{Inegi, 2022}) (Figure 1).

Sitio = Site

Figure 1 Location of the sampling sites of a pine borer, in Plan de Guadalupe community. 

The type of climate in the community is C(w₂)(w) corresponding to temperate sub-humid with summer rains (^{INEGI, 2008}). The dominant vegetation is pine-oak and oak-pine forest (^{Inegi, 2022}).

Three sampling areas were selected, in agreement with the community authorities, based on the presence of pine trees with yellowish and/or dry foliage, resin on the stems and small holes. The above symptoms occur in patches of the forest, so the sampling areas had different sizes and shapes, two of them only 50 m apart and the third 2 km away from the previous two (Figure 1). In each area, a 400 m² quadrant was established, where three samplings were carried out on different dates (March, April and September 2021), based on the methodological proposal of ^{Pacheco-Flores et al. (2006)}.

For the description and determination of the infestation level, the following procedure was carried out: a) Registration and marking of the damaged pines based on the presence of lumps on the stem, b) Counting the number of lumps and the height at which they were located, and c) Categorization of the level of infestation adapting the classification proposed by ^{Billings and Espino (2005)} for barking insects:

Level 1: The tree has a green crown and lumps of fresh resin.

Level 2: The tree is infested by larvae inside the bark, it presents a yellowish crown with dry and hard lumps along the stem.

Level 3: It is characterized because the tree has a reddish or brown crown, as well as dead trees without leaves.

Based on the methodology proposed by ^{Márquez (2005)}, the larvae were extracted from the affected stems with a machete, the damaged bark was removed to locate their location, they were taken with forceps to deposit them in transparent jars and later they were transferred to the Laboratory of Entomology of the Universidad Intercultural del Estado de Guerrero (UIEG) (Intercultural University of the State of Guerrero, UIEG) to process and fix them in 70 % alcohol. In addition, pupae were collected and monitored every three days, until the emergence of the adult in the months of May and June.

For the determination of the species, bibliographic material from ^{Cibrián et al. (1995}; ²⁰¹⁵⁾; likewise, adults reared in the laboratory were compared with the description of ^{Beutelspacher (1983)} and ^{Hernández (1983)}. The collected specimens were stored in the biological collection of the Laboratory of Entomology of the Universidad Intercultural del Estado de Guerrero (UIEG) (Intercultural University of the State of Guerrero).

The insect responsible for the damage to the pine trees in the study community corresponded to S. cardinalis, commonly known as the resin moth or pine borer. The species was collected from the stem of the trees with the presence of light pink lumps of resin. It was observed that the developing larva builds tunnels in the phloem and the cambium area (Figure 2). The pupae are reddish-brown in color, averaging 1.5 to 2.0 cm in length and 0.5 cm in width. The adults are moths that measure between 2.5 and 3.0 cm of expansion; the wings have reddish-orange scales and black venation. It is the first record of S. cardinalis as a pest species of forest importance for the state of Guerrero.

a) Resin on the stem b) larvae, c) pupa and d) adult. The scale bar for d) equals 1 cm.

Figure 2 Symptoms and signs of attack by Synanthedon cardinalis (Dampf, 1930).  

A total of 694 pine trees were recorded in the sampled sites, 64 of which had a borer (9.22 %). Likewise, 59 (8.50 %) of these individuals registered level 1 damage, two (0.28 %) level 2 and two (0.28 %) level 3. In site 1, which had 348 pines, 13 damaged individuals were counted (3.73 %); seven in the first sampling, two in the second, and four in the third. In site 2, with a total of 111 pines, 33 showed infestation (29.72 %) and it was in sampling one when 32 individuals were recognized, while in the third sampling one more case was added. In site 3, a total of 235 pines and 18 infested (7.6 %) were recorded, in sampling 1, 16 (6.80 %) infested individuals were recorded, and in the last two more pines were added.

The lumps were detected at different heights of the stem, in a range from 0 to 2.5 m above ground level, however, the averages show that in general these were located between 0.5 and 1.25 m in height, without infesting the middle or upper part of the stem (Table 1).

It was observed that the trees affected by S. cardinalis had an average number of lumps per tree between 1.75 and 3.76 (Table 1), which can be designated as a relatively low infestation. Exceptionally, a tree with up to 19 lumps was found at site 2, which undoubtedly influenced the average for that site. The range of the normal diameter of the sampled individuals was from 2 to 36 cm, with an average of 9.6 cm. The averages per site were 6.9, 9.7 and 11.28 respectively (Table 1).

^{Cibrián et al. (1995)} reported that S. cardinalis in Mexico is not considered a pest of economic importance and they classify it as a kind of secondary borer, which does not cause tree death, which coincides with the results of this study. ^{Peralta-Méndez and Alba-Landa (2004)} have documented the death of pine trees in the state of Veracruz (Naolinco) caused by this insect, but in the sites of this study the mortality attributed to it was only 0.43 %. However, ^{Del Río (1990)} mentioned that the damage caused by the larvae of the resin moth is the primary deterioration, and that it would be enough for a female moth to oviposit in an individual for three generations for it to die, so it is important monitor their and other insects in the temperate forests of the La Montaña region.

In the sampled areas of the Plan de Guadalupe community, the attacked trees presented dry and fresh pink and reddish resin. ^{Del Río (1990)} pointed out for the Purépecha forest region, state of Michoacán, S. cardinalis shows itself along the stem from the ground and congregates in certain places (around the branches), something similar to that identified in the pines of the Plan de Guadalupe community. On the other hand, the range (1 to 19) of the number of lumps per individual of Pinus pseudostrobus Lindl. is similar to that reported by ^{Ruiz-Montiel et al. (2018)}, who mention 1 to 10 lumps in P. patula Schltdl. & Cham. in the center of Veracruz State. Furthermore, they recorded similar data on P. rudis Endl. and P. teocote Schltdl. & Cham.

The average diameter of the attacked trees was 9.6 cm, a value consistent with that described by ^{Ruiz-Montiel et al. (2018)}, who mention that the trees affected by the resin moth had diameters of less than 10 cm.

The height of the clumps recorded in the different individuals was between 0 and 2.5 m; in this regard, ^{Hernández (1983)} stated that the damage of S. cardinalis in P. moctezumae Lamb. they occurred in trees of 10 to 59 cm of normal diameter, with heights of 7 to 12 m, while in P. patula it was 1 to 9 m in height. A possible explanation may be that S. cardinalis females prefer to oviposit in sites with higher larval activity. ^{Gentry and Wells (1982)} mentioned that the resin mixed with larvae feces (lump) stimulates the oviposition of the female of this insect, which indicates that the species of the Pinus genus are good hosts. The reviewed and quantified trees showed relicts of dry resin, in addition to alterations or deformities in the stem and fresh resin, which indicates that the larvae were there before, that they have already emerged and others that are developing.

In Plan de Guadalupe community, the economic impact was not estimated and, according to its level of infestation, S. cardinalis behaves as a secondary pest. However, it is necessary to carry out monitoring in the studied areas and others in the Mountain Region to know the distribution of this insect and recognize its dynamics.

This record of S. cardinalis is the first for the state of Guerrero. Likewise, the infestation levels recorded by this insect in the sampled areas confirm that it is not a pest of economic importance in the study area, at present.