Guillermo López-Guillén

Araecerus fasciculatus (Coleoptera: Anthribidae) is a cosmopolitan insect that infests various stored grains, including cocoa beans, producing significant economic losses. Cocoa beans are marketed under two processing methods: washed or fermented. However, during storage they may become infested by insects. In this study, the olfactory response of A. fasciculatus to volatile compounds emitted by unfermented washed, fermented, and infested cocoa beans was evaluated. Volatile compounds from cocoa beans were collected using dynamic aeration and analyzed by gas chromatography–mass spectrometry (GC-MS). Behavioral responses to beans, extracts, synthetic blends, 3-methylbutanoic acid, heptanal, and a binary blend (3-methylbutanoic acid plus heptanal) were evaluated in a Y-tube olfactometer. Antennal activity was determined by electroantennography (EAG). Chemical analysis revealed the presence of ketones, alcohols, esters, terpenes, acids, hydrocarbons, aldehydes, and pyrazines, with volatile profiles varying according to postharvest handling. In behavioral bioassays, unfermented washed beans did not attract either sex, fermented beans attracted both males and females, and infested beans attracted only males. The EAG analysis demonstrated that the volatile extract from fermented cocoa beans, as well as 3-methylbutanoic acid and heptanal, elicited the antennal responses. The binary blend did not elicit a significant attraction compared with the control, whereas each compound tested individually produced stronger responses. Males and females were attracted to 3-methylbutanoic acid at 0.001 µg, while heptanal attracted females at 0.1 and 0.01 µg and males at 1 and 10 µg. These findings identify key compounds in relation to the doses tested, providing insights for future management of A. fasciculatus in grain storage facilities.

Cocoa (Theobroma cacao L.) occupies approximately 53,000 ha in Mexico, distributed across the states of Tabasco (62%), Chiapas (37%), and Guerrero (1%). Its average yield is relatively low, at approximately 0.5 t ha⁻¹, which is comparable to the global average. As a crop native to tropical regions, cocoa cultivation, like agriculture in general, faces technical challenges that require technological innovations to enhance its sustainability. However, this study focused on observing and analyzing soil pH within the cocoa agroecosystem, not for the purpose of developing soil amendments, but rather to characterize its statistical behavior. Using 107 soil samples collected from this agroecosystem, a statistical analysis was conducted to evaluate the behavior of soil pH values. The dataset was fitted to five probability density functions (PDFs): Normal, Three-Parameter Lognormal (Lognormal 3P), Gamma, Three-Parameter Gamma (Gamma 3P), and Three-Parameter Weibull (Weibull 3P). The objective was to identify the probability density function that best represented the distribution of the observed data and to support probabilistic inferences regarding optimal pH ranges, acidity, and alkalinity within the cocoa agroecosystem. Accordingly, the aim of this research was to determine the probability density function that best describes the distribution of soil pH values in cocoa agroecosystems located in the states of Chiapas and Tabasco, Mexico.

Background: Mango (Mangifera indica L.) is a tropical fruit of significant economic, nutritional, and cultural importance. Its characteristic aroma results from a complex mixture of volatile organic compounds (VOCs) that vary by cultivar and developmental stage. Questions and/or Hypotheses: Does the composition of VOCs vary depending on the variety of mango in flowers and green and ripe fruit? A comparative chemical analysis of the VOCs emitted by flowers and fruits of 53 mango varieties grown in southeastern Mexico is proposed. Data description: We performed a chemical analysis of VOCs emitted by flowers and ripe and unripe fruits from 53 mango cultivars grown. Study site and dates: Samples were obtained from the Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP), specifically from the experimental station La Norteña, located in Tapachula, Chiapas, Mexico. Methods: Volatiles were extracted using solid-phase microextraction (SPME) and identified by Gas Chromatography–Mass Spectrometry (GC-MS). Results: Fifteen monoterpenes and sesquiterpenes were identified, with α-pinene, β-pinene, myrcene, 3-carene, limonene, α-copaene, and α-gurjunene being the most abundant compounds across all mango cultivars tested. Floral samples were dominated by light monoterpenes such as α-pinene, myrcene, and 3-carene; unripe fruits were abundant in 3-carene and β-pinene; and ripe fruits displayed higher proportions of α-pinene, 3-carene, and terpinolene. Conclusions: These tissue- and stage-specific patterns indicate the adaptive roles of compounds in pollination, fruit development, and seed dispersal. Our findings reveal slight chemical variations among cultivars, highlighting the significance of volatile profiling for the conservation, selection, and ecological understanding of mango diversity.

In nature, as occurs in soybean cultivation (Glycine max (L.) Merr.), yield is the result of the interaction of multiple factors (yield components) that determine this outcome. Based on this information, a multiple linear regression model (MLRM) was proposed, relating the effect of a dependent variable as a function of several independent variables. For this purpose, during the spring–summer 2023 cycle, an experiment with three soil management treatments—subsoiling, plowing, and harrowing—was conducted, distributed in paired plots of 0.50 ha each under rainfed conditions. At the reproductive stage (R8), 50 plants were randomly selected, and the following variables were individually measured: plant height, number of branches, nodes, pods, pods with one seed, two seeds, three seeds, and grain weight adjusted to 14% moisture content. The matrix of grain unit weight values versus plant components was analyzed using the proposed model, along with statistical assumptions to identify the best fit. Based on this, the objective of this research was to determine a multiple linear regression model to estimate the unit grain yield of soybean plants as a function of their yield components. The MLRM was determined based on plant height, number of pods, and number of pods with three seeds, achieving an acceptable coefficient of determination (R² = 0.93).

The physical action of subsoiling increases water infiltration, allowing the infiltrated water layer to reach the root zone of crops, including soybean, which was the focus of this research. The study was conducted in the Soconusco region, Chiapas, located in the southern Pacific region of Mexico, where approximately 12,000 hectares of soybean are cultivated under rainfed conditions, supported by a six-month rainy season (May–October) suitable for crop growth and production. However, since 1975, soil preparation for planting has been carried out under variable moisture conditions which, combined with repeated machinery traffic during plowing and harrowing operations, has caused soil compaction, currently presenting varying levels of compaction. Therefore, research was conducted during 2019, 2022, and 2023 using an experimental design consisting of three treatments: subsoiling and two control treatments, conventional plowing and soil harrowing. Treatments were established in paired plots of 0.5 ha (50 m × 100 m), with subsoiling mainly performed during the dry season (April 2019) at a depth of 60 cm. In each treatment, infiltration was measured to estimate its parameters, including infiltration rate, cumulative infiltrated depth, and saturated hydraulic conductivity. Under the hypothesis that subsoiling increases infiltration and in situ soil moisture, the objective was to evaluate soil moisture behavior within the crop root profile as a function of subsoiling and infiltration and its effect on soybean yield under rainfed conditions.

Moniliophthora roreri (Cif.) Evans et al. is the causal agent of frosty pod rot (cacao moniliasis). This disease represents the main phytosanitary problem that cacao production faces in Latin America. The vast destructive capacity of frosty pod rot leads to high economic losses. This study aimed to determine the genetic diversity of M. roreri associated with cacao trees growing around the Soconusco area in Chiapas, Mexico, through the inter simple sequence repeat analysis or ISSR. The study analyzed 145 strains of M. roreri isolated from 17 sites belonging to 12 regions in the Soconusco area, from Suchiate in the south, near the Guatemala border, to Acapetahua in the north of Chiapas. According to the results of the analysis, two genetic groups were identified: the first one was located in the north of the Soconusco area, and the second in the south. The analysis of molecular variance (AMOVA) indicated higher variability in the populations (59.64%) among sampling sites than within the populations (40.35%), and together with the Mantel analysis (P = 0.034), it indicated that the gene flow of M. roreri is affected by landscape features, such as mountains, roads, and rivers.

Anthracnose is a phytosanitary issue caused by various species of Colletotrichum. This study aims to revise the presence of Colletotrichum in the south of Mexico (the Soconusco area in Chiapas) and assess the inhibitory capacity of Paenibacillus sp. NMA1017 against Colletotrichum in in vitro and field experiments. The study involved sampling pods with anthracnose from 17 sites in the Soconusco area, Chiapas, Mexico. The incidence of the disease ranged from 0.6 to 11.63%. A total of 142 isolates exhibiting the morphological characteristics of the Colletotrichum genus were obtained. Fifty selected isolates were identified using the ITS region and were classified as Colletotrichum gloeosporioides with 99% similarity. The concatenation of morphological and physiological characteristics resulted in nine main clusters. The in vitro test showed that Paenibacillus sp. NMA1017 inhibited the fungal growth of selected strains by 30–50%. The field experiments included three commercial biocontrol agents, Paenibacillus sp. NMA1017, and a water control. The incidence of anthracnose (control with water) ranged from 32 to 65%, while the commercial biocontrol agents and Paenibacillus showed an incidence range of 12 to 20%. These findings support the use of Paenibacillus sp. NMA1017 as a biocontrol agent for cacao anthracnose.

The soybean weevil Rhyssomatus nigerrimus (Fahraeus), is an economically important pest that attacks soybean (Glycine max (L.) Merrill] crops in northern and southern Mexico. Rhyssomatus nigerrimus can be considered a specialist insect because it selects soybean plants for its reproduction and feeding. However, when the rainy season begins, new emerged adult weevils can feed and take refuge in other alternate host plants, such as Rottboellia cochinchinensis (Lour.) W. Clayton, Hyparrhenia rufa (Nees) Stapf, Sorghum halepense (L.) Persoon and Ipomoea trifida (Kunth) G. Don when soybean is not available. These host plants can potentially be used as attractant plants. The objectives of this study were a) to determine the attraction response of adult R. nigerrimus to four species of alternate host and their volatiles extracts, b) to identify the volatile compounds present in each alternate host plant species volatiles extracts, and c) to determine the antennal response (EAG) of female and male R. nigerrimus to volatiles extracts from the alternate host plants. The attraction bioassays were conducted in an arena, on which we evaluate the R. nigerrimus response to foliage and extract of the alternate host plants. The antennal response of R. nigerrimus females and males to volatiles from alternate host plants was determined by the electroantennogram (EAG) technique. Female and male R. nigerrimus were more attracted by the foliage and extracts from I. trifida, R. cochinchinensis, H. rufa and S. halepense than to the control. The strongest EAG response of female and male R. nigerrimus was observed with the volatiles from S. halepense, H. rufa, I. trifida and R. cochinchinensis. The control elicited the weakest antennal response. The GC-MS analysis of the volatile compounds from I. trifida, S. halepense, H. rufa and R. cochinchinensis revealed the presence of 17, 9, 9 and 9 compounds, respectively. Major volatiles compounds could be used as lures in traps to control R. nigerrimus.

Se reporta por primera vez a Promecops leucothyrea Fahraeus (Coleoptera: Curculionidae), en Chiapas. Los adultos se alimentan en plantas de soya en la etapa VC (hojas unifoliadas desenrolladas) hasta R2 (plena floración). Aunque P. leucothyrea, se encuentra en este momento solo en ciertas localidades con cultivos de soya en Chiapas, a nuestro conocimiento, probablemente pueda esparcirse a otras partes de México. Otras plantas hospederas de P. leucothyrea que se encontraron en Chiapas son Rottboellia cochinchinensis (Lour.) W. Clayton, Sorghum halepense (L.) Persoon (Poaceae), Ipomoea trifida (Kunth) G. Don (Convolvulaceae), Azadirachta indica A. Juss. (Meliaceae), Hamelia rovirosae Wernham. (Rubiaceae), Malvastrum coromandelianum (L.) Garcke (Malvaceae).

Excessive use of insecticides has led to resistance of some pathogenic organisms (nematodes, bacteria and fungi), environmental contamination, and the presence of hazardous residues. Therefore, the aim of the present study was to evaluate synthetic metabolites derived from previous studies with edible mushrooms against the soybean weevil Rhyssomatus nigerrimus Fahraeus (Curculonidae) because of the relevance of pest control in an economically important crop. Furthermore, this is one of the first studies where edible fungal molecules are evaluated for the control of these insects. Initially, two in vitro tests (toxic effect and immersion) were evaluated against R. nigerrimus. In these tests, sensitivity and viability were determined in the 2% Tween control in water. For these two tests, the synthetic metabolites pentadecanoic acid (PNA), palmitic acid (PMA), stearic acid (STA), linoleic acid (LNA), β-sitosterol (βT) were evaluated individually as well as in combinations, “the fraction of standards (E1)”. Based on the results obtained, the dip test was selected to evaluate the mixtures of two standards (1. PMA + βT, 2. PMA + PNA, 3. PMA + LNA, 4. PMA + STA, 5. STA + βT, 6. STA + PNA, 7. STA + LNA, 8. PNA + βT, 9. PNA + LNA, 10. LNA + βT), three (1. PNA + βT + LNA, 2. PNA + βT + STA, 3. STA + LNA + PNA and 4. STA + LNA + βT) and four (PNA, βT, LNA and STA). The results showed that the mixture of three standards caused a higher percentage of mortality relative to the control group: l. PNA + βT + LNA and 2. PNA + βT + STA with 54.44 and 48% mortality of R. nigerrimus insects exposed for 15 days. These results show the importance of evaluating mixtures of molecules against R. nigerrimus.