The fall armyworm, Spodoptera frugiperda (J. E. Smith), is one of the main pests of corn in many areas of the American continent. The reliance on pesticides to control fall armyworm has led to the ...development of insecticide resistance in many regions. We determined the resistance levels of fall armyworm to insecticides of different modes of action in fall armyworm populations from Puerto Rico and several Mexican states with different insecticide use patterns. Mexican populations that expressed higher resistance ratios (RR50) were: Sonora (20-fold to chlorpyriphos), Oaxaca (19-fold to permethrin), and Sinaloa (10-fold to flubendamide). The Puerto Rico population exhibited a remarkable field-evolved resistance to many pesticides. The RR50 to the insecticides tested were: flubendiamide (500-fold), chlorantraniliprole (160-fold), methomyl (223-fold), thiodicarb (124-fold), permethrin (48-fold), chlorpyriphos (47-fold), zeta-cypermethrin (35-fold), deltamethrin (25-fold), triflumuron (20-fold), spinetoram (14-fold). Spinosad (eightfold), emamectin benzoate and abamectin (sevenfold) displayed lower resistance ratio. However, these compounds are still effective to manage fall armyworm resistance in Puerto Rico. Fall armyworm populations from Mexico show different levels of susceptibility, which may reflect the heterogeneity of the pest control patterns in this country. The status of insecticide resistance in the fall armyworm from Puerto Rico indicates a challenging situation for the control of this pest with these insecticides in the close future. Lessons learned from this research might be applied in regions with recent invasions of fall armyworm in Africa.
Evolution of pest resistance to pesticides is an urgent global problem with resistance recorded in at least 954 species of pests, including 546 arthropods, 218 weeds, and 190 plant pathogens. To ...facilitate understanding and management of resistance, we provide definitions of 50 key terms related to resistance. We confirm the broad, long-standing definition of resistance, which is a genetically based decrease in susceptibility to a pesticide, and the definition of “field-evolved resistance,” which is a genetically based decrease in susceptibility to a pesticide in a population caused by exposure to the pesticide in the field. The impact of field-evolved resistance on pest control can vary from none to severe. We define “practical resistance” as field-evolved resistance that reduces pesticide efficacy and has practical consequences for pest control. Recognizing that resistance is not “all or none” and that intermediate levels of resistance can have a continuum of effects on pest control, we describe five categories of field-evolved resistance and use them to classify 13 cases of field-evolved resistance to five Bacillus thuringiensis (Bt) toxins in transgenic corn and cotton based on monitoring data from five continents for nine major pest species. We urge researchers to publish and analyze their resistance monitoring data in conjunction with data on management practices to accelerate progress in determining which actions will be most useful in response to specific data on the magnitude, distribution, and impact of resistance.
Jasmonic acid (JA) is a fatty acid-derived signaling molecule that regulates a broad range of plant defense responses against herbivores and some microbial pathogens. Molecular genetic studies in ...Arabidopsis have established that JA also performs a critical role in anther and pollen development but is not essential for other developmental aspects of the plant's life cycle. Here, we describe the phenotypic and molecular characterization of a sterile mutant of tomato (jasmonic acid-insensitive1 jai1) that is defective in JA signaling. Although the mutant exhibited reduced pollen viability, sterility was caused by a defect in the maternal control of seed maturation, which was associated with the loss of accumulation of JA-regulated proteinase inhibitor proteins in reproductive tissues. jai1 plants exhibited several defense-related phenotypes, including the inability to express JA-responsive genes, severely compromised resistance to two-spotted spider mites, and abnormal development of glandular trichomes. We demonstrate that these defects are caused by the loss of function of the tomato homolog of CORONATINE-INSENSITIVE1 (COI1), an F-box protein that is required for JA-signaled processes in Arabidopsis. These findings indicate that the JA/COI1 signaling pathway regulates distinct developmental processes in different plants and suggest a role for JA in the promotion of glandular trichome-based defenses.
Residue profiling was used to determine the degradation curves of four key insecticides registered for use in US tart cherries. Single and multiple application treatment regimens with minimum and ...maximum seasonal applications were tested for their effects on residue levels at harvest. The effects of the cherry washing procedure were also tested. The residue profiles suggest that fenpropathrin, cyantraniliprole, phosmet, and spinetoram would be relatively low risk for US tart cherry growers to use when exporting from the US to most prospective international markets. Fenpropathrin exceeded the European Union's MRL at harvest for single or multiple applications and unwashed or washed treatments, making fenpropathrin a moderate risk for export to the EU.
Bt: Mode of action and use Whalon, Mark E; Wingerd, Byron A
Archives of insect biochemistry and physiology,
December 2003, Letnik:
54, Številka:
4
Journal Article
Recenzirano
The insecticidal toxins from Bacillus thuringiensis (Bt) represent a class of biopesticides that are attractive alternatives to broad-spectrum "hard" chemistries. The U.S. Food Quality Protection Act ...and the European Economic Council directives aimed at reducing the use of carbamate and organophosphate insecticides were expected to increase the use of narrowly targeted, "soft" compounds like Bt. Here we summarize the unique mode of action of Bt, which contributes to pest selectivity. We also review the patterns of Bt use in general agriculture and in specific niche markets. Despite continued predictions of dramatic growth for biopesticides due to US Food Quality Protection Act-induced cancellations of older insecticides, Bt use has remained relatively constant, even in niche markets where Bt has traditionally been relatively high.
The codling moth (
Cydia pomonella
L.) is a significant pest of pome fruit throughout the world. Behavioral and ovicidal activities of five non-host plant extracts (
Arctium lappa
,
Bifora radians
,
...Humulus lupulus
,
Verbascum songaricum
,
Xanthium strumarium
), synthetic sex pheromone, (
E
,
E
)-8,10-dodecadienol (codlemone), and the plant volatile lure, (2
E
,4
Z
)-2,4-decadienoate (pear ester) were evaluated against the codling moth,
C. pomonella
L. Codlemone elicited the greatest electroantennogram (EAG) response (6.2 ± 1.2 mV) of the compounds tested from male
C. pomonella
while pear ester elicited 1.7 ± 0.1 mV EAG response in female moths. Codlemone attracted 34.5% of male
C. pomonella
in olfactometer studies, and it was followed by the
X. strumarium
extract with 24.8%. There was a significant difference between the behavior of unmated and mated females.
V. songaricum
extract was the most active extract, attracting 25.4% of unmated females. However, mated
C. pomonella
females exhibited greatest attraction to pear ester. In a wind tunnel bioassay, combining
X. strumarium
with codlemone significantly increased the response of male upwind flight and source contact as compared with codlemone alone. All plant extracts, except for
V. songaricum
, significantly reduced the number of eggs laid. The plant extracts exhibited some toxic effects to eggs, and hatching rate of eggs was reduced as compared with the control. Our results indicate that some of the plant extracts tested are potential candidates for practical use after elucidation and characterization of active compound(s).
Methanol extracts of
Bifora radians
,
Arctium lappa
,
Humulus lupulus
and
Xanthium strumarium
were tested against the North American grape berry moth,
Paralobesia viteana
in laboratory and greenhouse ...assays. Egg hatch was reduced by
B. radians
and
X. strumarium
extracts, whereas larval mortality was observed in response to
B. radians
,
X. strumarium
and
A. lappa.
Given the high mortality against egg and larval stages of this pest caused by extracts of
B. radians
, further studies were performed to determine the dose–response relationships between extracts of this plant and oviposition and egg hatch of
P. viteana
. There was a significant reduction in egglaying and egg hatch with increasing extract concentration, with 0.1% extracts providing 80% mortality and 1% extracts causing more than 90% control. This study demonstrates the potential of this plant extract for crop protection against a key pest of grapes and suggests that additional crop pests and field tests should be pursued to determine the efficacy of
B. radians
extracts as a biopesticide.
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