The fall armyworm, Spodoptera frugiperda Smith & Abbot (Lepidoptera: Noctuidae), is a key pest of corn, Zea mays L. (Poales: Poaceae), in Mexico. The development of genetically modified (GM) corn hybrids for resistance to this insect, with the inclusion of several genes coding for proteins Cry1Ab, Vip3Aa20, and mCry3A of Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) (Bt), offer an alternative to conventional insecticides to control this pest. Resistance to fall armyworms of the GM corn hybrids Agrisure 3000 GT, Agrisure Viptera 3110, and Agrisure Viptera 3111 was evaluated in 4 locations at Sinaloa for a 3 yr period. Damage evaluation showed that the maize hybrids with the Bt gene insertion were not affected by the fall armyworm as compared with their respective isolines, which were seriously damaged. The results reaffirm the insect control benefits provided by this technology and provide a baseline for resistance management.

Red spider mites, Tetranychus merganser Boudreaux (Acari: Tetranychidae), is an agricultural pest that causes economic losses in papaya and nopal crops in Mexico. The aim of this research was to assess antibiosis and antixenosis as resistance mechanisms in seven host plants (Thevetia ahouai, Carica papaya, Phaseolus vulgaris, Moringa oleifera, Pittosporum tobira, Helietta parvifolia, Capsicum annuum var. glabriusculum) to red spider mites. Antixenosis was evaluated by non-preference for oviposition and feeding, antibiosis by infinitesimal rate of increase, finite rate of increase and doubling time, and the percentage of spider mites mortality. Oviposition and damage by feeding of T. merganser were significantly greater on C. papaya than on the other host plants. The growth rate of the spider mite was significantly lower in P. tobira and T. ahouai than in the other host plants. The percentage of hatched eggs of T. merganser was significantly higher in P. vulgaris than in the other plant species. Based on the demographic parameters, survival, food intake, and oviposition, these results indicated that compared with C. papaya, P. tobira and T. ahouai were more resistant. These results may be due to the fact that they were plants species of different families. The resistant plants can be studied as alternatives in the management of T. merganser.

The use of nanoparticles (NPs) has generated an alternative pest control. The objective was to evaluate the insecticidal effect of zinc oxide nanoparticles (ZnO NPs), titanium dioxide nanoparticles (TiO2 NPs), and their combination on Bactericera cockerelli (Hemiptera: Triozidae) second-stage nymphs under laboratory and greenhouse conditions in tomato. The laboratory research was carried out with the leaf immersion bioassay method under a complete randomized design, and in the greenhouse by direct plant spraying under a randomized block design; in both designs, a control without NPs was added. Mortality was recorded every 24 h for 4 days. Both NPs in the laboratory and greenhouse showed toxicity to B. cockerelli nymphs. Results in the laboratory showed that NPs significantly caused increased mortality of 88, 99, and 100% 96 h after treatment of ZnO NPs, TiO2 NPs, and their combinations, at 1000, 100, and 250 ppm, respectively. Direct spray of plants in the greenhouse showed low mortality with 27, 32, and 23% after 96 h of ZnO NPs, TiO2 NPs, and their combinations, at 3000, 500, and 250 ppm, respectively. These results on B. cockerelli control seem promising. Nanoparticles as insecticides are a novel strategy, however, further investigation is required in field tests to obtain suitable efficacy for use in a pest management system.

The objective of this study was to determine the oxidative stress and the physiological and antioxidant responses of coriander plants (Coriandrum sativum) grown for 58 days in soil with zinc oxide nanoparticles (ZnO NPs) and zinc sulfate (ZnSO4) at concentrations of 0, 100, 200, 300, and 400 mg of Zn/kg of soil. The results revealed that all Zn compounds increased the total chlorophyll content (CHLt) by at least 45%, compared to the control group; however, with 400 mg/kg of ZnSO4, chlorophyll accumulation decreased by 34.6%. Zn determination by induction-plasma-coupled atomic emission spectrometry (ICP–AES) showed that Zn absorption in roots and shoots occurred in plants exposed to ZnSO4 at all concentrations, which resulted in high levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA). Only at 400 mg/kg of ZnSO4, a 78.6% decrease in the MDA levels was observed. According to the results, the ZnSO4 treatments were more effective than the ZnO NPs to increase the antioxidant activity of catalase (CAT), ascorbate peroxidase (APX), and peroxidases (POD). The results corroborate that phytotoxicity was higher in plants subjected to ZnSO4 compared to treatments with ZnO NPs, which suggests that the toxicity was due to Zn accumulation in the tissues by absorbing dissolved Zn++ ions.

Antifungal activity of zinc oxide (ZnO) and ZnO nanoparticles (ZnO NPs) was evaluated on the control of Fusarium oxysporum Schltdl. (Nectriaceae) under laboratory and greenhouse conditions. In vitro evaluation, poisoned culture media was prepared, and an explant was placed in the centre of solid medium. The experimental design was completely randomized with 18 treatments. Mycelial growth and conidia concentration were evaluated. Subsequently, three treatments (3,000, 1,500, 100 ppm) of ZnO NPs and ZnO were chosen for their evaluation in the greenhouse in tomato plants of Floradade variety under a randomized block design. Inoculation was carried out with a 1x107 conidia per mL suspension of F. oxysporum, when the plants presented the third pair of true leaves. Later, the application of different concentrations of ZnO and ZnO NPs was carried out; in this investigation, the incidence and severity and plant height were evaluated into account to determine the treatment effect on F. oxysporum. In vitro, the best treatments in mycelial growth inhibition were the high concentrations of ZnO NPs from 1,600 to 3,000 ppm with 81%–83%, and in the sporulation of the fungus, they were also those that inhibited from 82.57% to 83.85%. In greenhouse, the treatments that reached the highest plant height were ZnO NPs from 1,500 to 3,000 ppm, with a range of 166.0–175.40 cm, with a severity on the scale of 0.40–0.80 and an incidence of 20%–40%. ZnO NPs have a potential application as an antifungal agent and can be used to control the spread of F. oxysporum in tomato plants, in addition to improving the promoter effect related to the Zinc activity as a precursor in auxins synthesis, cytokinins and gibberellins biosynthesis, as well as the induction of higher activity of antioxidant enzymes useful in response to the pathogens attack.