Ceratitis capitata (Wiedemann, 1824) is the main insect pest of fruits worldwide. The objective of this study was to evaluate the toxicity and residual effects of the ready-to-use toxic baits Success 0.02CB (0.24 g of active ingredient [a.i.] per liter of spinosad) and Gelsura (6 g of a.i./liter of alpha-cypermethrin) and to compare them with other food lures containing spinosad and malathion mixed with hydrolyzed protein (Biofruit 5% and Flyral 1.25%), Anamed without dilution or sugarcane molasses (7%) against adult C. capitata in laboratory and greenhouse trials. Ceratitis capitata adults were highly susceptible to all toxic bait formulations (mortality > 80%) until 96 h after exposure. The lowest LT50 (hours) of toxic baits were 2.32 (Gelsura at 4,000 mg/liter), 4.26 (Gelsura at 2,000 mg/liter), 4.28 (Anamed + malathion) and 4.89 (sugarcane molasses + malathion), while formulations containing spinosad (Biofruit, Flyral, Anamed and Success 0.02CB) showed LT50 of approximately 11 h. Without rain, Gelsura (2,000 mg/liter) and all spinosad formulations provided mortality superior to 80% 14 d after application. Gelsura and Anamed + spinosad showed higher resistance to a 5-mm simulated rain, similar to Anamed + malathion, while the other formulations had its efficacy decreased. All toxic baits were effective on adult C. capitata in residual experiments without rain while Anamed + spinosad caused high adult mortality after 5 to 25 mm rains. Gelsura and Anamed + spinosad can be used to replace toxic baits containing malathion for C. capitata population management.
The objective of this work was to assess the lethal concentration and lethal time (LC and LT) of spinosad and spinetoram, combined with different food lures, and their residual effects on South American fruit fly (Anastrepha fraterculus). The toxic baits were offered in eight concentrations (2, 6, 14, 35, 84, 204, 495, and 1,200 mg L-1), combined with the following food lures: 7% sugarcane molasses, 3% Biofruit, 1.5% CeraTrap, 1.25% Flyral, 3% Samaritá Bait, and 3% Samaritá Tradicional; diluted food lures in water were used as controls. The residual effect of the formulations at 96 mg L-1 concentration were evaluated for 21 days and were compared with that of the commercial bait Success 0.02 CB. Both insecticides were toxic to adults of A. fraterculus, and mortality varied with the food lure used. The LC50and LT50ranged from 15.19 to 318.86 mg L-1and from 11.43 to 85.93 hours, respectively. Spinosad was 2 to 36 times as toxic as spinetoram when combined with different hydrolyzed proteins. Toxic baits formulated with spinosad and spinetoram (96 mg L-1) caused mortality equivalent to the one by Success 0.02 CB (90.2%), when assessed on the day of application. Toxic baits formulated with 3% Biofruit + spinosad and 3% Samaritá Bait + spinetoram are effective for managingA. fraterculusand provide up to seven days of residual effect in the absence of rain; however, only Success 0.02 CB caused more than 80% mortality for up to 21 days.
Bemisia tabaci (MEAM1) represents a species of economic importance in soybean. One of the obstacles to the management of B. tabaci is the quantification of damage by the pest because damage is indirectly inferred through losses in productivity. The objective of this study was to characterize the influence of B. tabaci feeding on soybean by assessing effects on photosynthetic parameters and the sugar and starch content of soybean leaves. The goal was to identify the optimal parameter to directly quantify pest damage on crop yield. Correlation networks were created among data on sugar content (fructose, glucose, and sucrose), starch and photosynthetic parameters (initial fluorescence, performance index on absorption basis, and turn-over number), and the number of nymphs at each of three infestations level (low, medium, and high) during both the vegetative and reproductive stage of the crop. In general, nymphs were more abundant during the vegetative stage. Starch content was strongly correlated with nymph density. A strong positive correlation was observed between fructose and nymph density during the vegetative stage. Among the photosynthetic parameters, the turn-over number N was positively correlated with nymph density at a low-infestation level and negatively correlated with nymphs when they occurred at a high-infestation level. B. tabaci feeding affected the plant’s physiology and its interaction is reflected in part by the relationships among photosynthetic parameters as well as the levels of sugars and starch. This understanding might be useful in developing better monitoring tools for pest management.
Anastrepha fraterculus (Wiedemann, 1830) is the main pest of fruit in southern Brazil. The use of toxic baits is one of the alternatives for its management. In this study, the toxic baits Anamed + malathion (10,000 mg/liter), Flyral 1.25% + malathion (2,000 mg/liter), and Gelsura (alpha-cypermethrin, 2,000 and 4,000 mg/liter) were highly toxic to the adults of A. fraterculus (lethal time [LT50] < 7 h). In contrast, Success 0.02 CB had an LT50 of 48.4 h. In the absence of rain, all the formulations had residual effects (>90% mortality) on A. fraterculus adults up to 21 d after treatment (DAT). In the presence of 5, 25, and 50 mm of rainfall, there was a significant reduction in the residual effect over time. However, with up to 50 mm of rain, Anamed + malathion and Gelsura 2,000 and 4,000 mg/liter caused between 43.0 and 79.0% of mortality. In the field, during two consecutive seasons (2015/2016 and 2016/2017), applications of Gelsura 2,000 mg/liter (four applications/season) caused population suppression of the pest throughout the apple fruiting period. However, in the 2016/2017 season, in the area using Gelsura, a higher percentage (≈12%) of apple fruits damaged by A. fraterculus females was observed when compared with the area with insecticide application (damage <3%). The toxic bait Gelsura (2,000 and 4.000 mg/liter) was shown to be promising for use in the management of A. fraterculus, with results similar to those with the application of synthetic insecticides.
Although monitoring insect pest populations in the fields is essential in crop management, it is still a laborious and sometimes ineffective process. Imprecise decision-making in an integrated pest management program may lead to ineffective control in infested areas or the excessive use of insecticides. In addition, high infestation levels may diminish the photosynthetic activity of soybean, reducing their development and yield. Therefore, we proposed that levels of infested soybean areas could be identified and classified in a field using hyperspectral proximal sensing. Thus, the goals of this study were to investigate and discriminate the reflectance characteristics of soybean non-infested and infested with Bemisia tabaci using hyperspectral sensing data. Therefore, cages were placed over soybean plants in a commercial field and artificial whitefly infestations were created. Later, samples of infested and non-infested soybean leaves were collected and transported to the laboratory to obtain the hyperspectral curves. The results allowed us to discriminate the different levels of infestation and to separate healthy from whitefly infested soybean leaves based on their reflectance. In conclusion, these results show that hyperspectral sensing can potentially be used to monitor whitefly populations in soybean fields.
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