The maximum entropy algorithm (MaxEnt) was used to create a model of the suitable environment for the cactus weevil, Cactophagus spinolae (Gyllenhal) (Coleoptera: Curculionidae), in Mexico and to analyze the climatic factors influencing the weevil's potential distribution and possible impacts on another Cactaceae species. Areas located west of the Transmexican Volcanic Belt, south of the Mexican Plateu, east of the Balsas Basin, and northwest of the Sierra Madre del Sur biogeographical provinces were found to be more suitable for the emergence of the cactus weevil. The climatic variables that determine the distribution of C. spinolae were seasonal temperatures (24.5%) and precipitation of coldest quarter (24.0%). The commercial production areas of edible Opuntia Mill. (prickly pear cactus and barbary fig) and pitahaya in Central Mexico match with the environmental suitability calculated for the cactus weevil.

The dissipation of three field-applied pesticides (chlorothalonil, chlorpyrifos, and malathion), on cultivated prickly pear (Opuntia ficus-indica (L.) Mill.) pads was studied. The extraction of pesticides was carried out using the European quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction technique and detection was carried out using tandem liquid chromatography with mass spectrometry. At harvest, 15 days after application, pesticide dissipation was below the level of detectability. Dissipation curves for prickly pear pads fit to a first-order kinetic equation. Two initial concentration levels were used for each pesticide. The approximate dissipation time for all pesticides studied was similar (10 days) and the half-life time was around six days. Final concentrations for the three pesticides were below the reference maximum residue level (MRL) (0.01 mg/kg), which suggests that these products can be applied safely in the commercial production of prickly pear pads at the established concentrations.

The presence of pesticide residues in vegetable and fruit products, as a consequence of inappropriate application in some cases, constitutes a risk to the health of the exposed population. In Mexico, the official norm, NOM-003-STPS-1999, only allows the use of pesticides with the phytosanitary registry, the responsible state commission for the control of the process and use of pesticides and toxic substances, which recommends doses and permitted crops. Despite the above, it is still common to find pesticide residues in some vegetable products. In this study, the following were detected: Chlorpyriphos, Dimetomorph I, Malathion, Omethoate, Carbendazim, and Imidacloprid in Nopal. The study was carried out in two collection centers located in the state of Morelos. In total, sixty samples were taken, thirty for each collection center, for a period of 10 months. To determine the pesticide residues, the analytical methodology was used, according to the guide, SANTE/11945/2015; in a laboratory accredited by the Mexican Accreditation Entity A. C. in the norm, NMX-EC-17025-IMNC-2006. The procedure for extracting analytes was carried out using the method, QuEChERS. The highest concentration of the pesticides detected in the samples obtained from the non-Certified Supply Center were Chlorpyrifos 0.309 mg/kg (MRL 0.01), Dimetomorf I 0.029 mg/kg (MRL 0.01), Malathion 0.155 mg/kg (MRL 0.01), Omethoate 0.032 (MRL 0.01), Carbendazim 0.090 mg/kg (MRL 0.01), and Imidacloprid 0.058 mg/kg (MRL 0.01). Thirty percent of the samples analyzed showed pesticide residues; the most frequent were Carbendazim. The results for the estimated daily intake (EDI) oscillated between 6.5 × 10⁻⁵ and 1.3 × 10⁻⁴ mg/kg body weight for the vegetable, Nopal. In principle, it could be concluded that the consumption of Nopal with pesticide residues does not represent any toxicological risk for human health, however, the risk cannot be ruled out due to the intake of other vegetables and fruits that are cultivated in the Mexican Republic, which probably present pesticide residues, which together would raise potential risks to human health.

Background: mango anthracnose, caused by Colletotrichum gloeosporioides, is the main mango disease in pre and post-harvest. Mainly synthetic fungicides have been used in its management, which has negatively impacted the environment and the health of workers. The induction of resistance in fruits by biological, physical or chemical means is considered a sustainable and safe strategy for the management of post-harvest diseases of fruits and vegetables. Methyl jasmonate (MeJa) and salicylic acid (AS) are natural and safe compounds that represent a promising alternative in post-harvest control. Objectives: to determine the effect of MeJa and AS on mycelial growth and spore germination of Colletotrichum sp., under in vitro conditions, and to evaluate the effect on development of postharvest damage caused by the pathogen in mango fruits treated with MeJa and AS. Methodology: the activity of MeJa and AS in the germination of spores and the mycelial growth of Colletotrichum sp., were evaluated in culture medium Broth Papa Dextrose and Papa Dextrose Agar, respectively. Healthy mango fruits were treated by immersion with MeJa and AS solutions at 1 and 10 mM for 5 min, and 24 h later they were inoculated with Colletotrichum sp., to evaluate the effect on the diameter of the lesion caused by the fungus to the 6 and 12 days after inoculation (dai). Results: MeJa and AS inhibited the germination of Colletotrichum sp., spores after 24 hours of incubation in vitro, while the mycelial growth of the fungus in PDA medium, 1 and 10 mM of MeJa and AS, showed significant reductions in growth in comparison to control. In fruits, it was observed that the 10 mM MeJA and AS treatments significantly reduced the diameter of the lesion caused by the fungus, compared to the control fruits at 12 dai. Implications: future trials should evaluate other concentrations of MeJa and AS in other mango varieties to assess the response to anthracnose. Conclusions: MeJa and AS inhibited spore germination and mycelial growth of Colletotrichu sp., under in vitro conditions, while in mango fruits these inducers significantly reduced the diameter of the lesion caused by this fungus, which suggests that both products can reduce the damage caused by Colletotrichum sp., in mango fruits.

Objective: To describe Fusarium oxysporum f. sp. niveum (Fon) as the causal agent of vascular withering in the watermelon crop (Citrullus lanatus (Thunb.) Matsum and Nakai). Design/Methodology/Approach: A review of scientific literature (scientific books, notes and articles) was carried out about Fon as the causal agent of vascular withering in the watermelon crop; biology, symptoms, disease cycle, isolation and management alternatives. Results: Withering from Fusarium in watermelon is the main fungal disease of this crop worldwide. Necrosis of the vascular tissue and withering of the plant are the most characteristic symptoms of the disease. There are four races of this fungus (Fon race 0, 1, 2 and 3); the commercial varieties of watermelons have different degrees of resistance to these races. Practices such as the correct diagnosis, use of grafts, solarization, fungicides, biological products and genetic resistance can significantly reduce the impact of the disease on the production. Findings/Conclusions: In Mexico, knowledge about vascular withering of watermelon is scarce despite this disease being one of the factors that limits commercial production. The greatest knowledge about the symptoms, the fungus’s biology, presence and distribution of races, diagnosis and alternatives of Fon management, will allow integrating appropriate management practices that favor the commercial production of the crop.

Vascular wilt caused by Fusarium oxysporum f. sp. niveum (Fon) is the main fungal disease of watermelon crops. Acibenzolar-S-methyl (ASM) is an inducer of plant defenses, which is effective against diseases caused by viruses, bacteria and fungi. In the present study, the effect of ASM on mycelial growth, spore germination and the reduction of the severity of wilting caused by Fon1, as well as its toxicity in watermelon plants was evaluated. The inoculation of the fungus was carried out four days after the application, via irrigation and foliar, of the ASM at concentrations of 15, 20, 30 and 40 mg L-1 in seedlings with two true leaves of the Sugar Baby variety, which does not have Fon resistance genes. In vitro results showed that ASM has a direct effect on spore germination and mycelial growth of Fon1. Also, the application of the defense inducer in watermelon plants significantly reduced (P < 0.05) the severity of wilt caused by Fusarium. The application via irrigation of the defense inducer (15 mg L-1) was more effective than the foliar application, since it reduced the severity of wilting caused by Fon1 in watermelon plants by 100%. The doses of 30 and 40 mg L-1 caused toxicity symptoms, since the plants showed significantly lower height, number of leaves and fresh aerial weight, compared to non-inoculated and untreated plants.