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Fall armyworm, Spodoptera frugiperda (J.E. Smith), and Southwestern corn borer, Diatraea grandiosella Dyar, are economically important pests of maize (Zea mays L.) in the southeastern United States. These insects attack plants in both the vegetative and reproductive stages of growth. Plant resistance is widely considered a desirable means for reducing losses to both insects, and corn germplasm lines with resistance to leaf feeding damage have been developed and released. Fall armyworm and southwestern corn borer larvae feeding on resistant genotypes grow more slowly than those feeding on susceptible genotypes. The objectives of the investigation were to evaluate 20 single cross maize hybrids for leaf feeding damage by southwestern corn borer and fall armyworm, to compare larval growth on laboratory diets prepared from lyophilized leaf tissue of single cross hybrids with different levels of resistance to leaf feeding, and to determine whether larval growth differed between diets prepared from leaf tissue collected from plants previously infested with southwestern corn borer or fall armyworm and non-infested plants. Both fall armyworm and southwestern corn borer larvae weighed significantly less when fed on laboratory diets prepared from lyophilized leaf tissue of resistant single cross hybrids than susceptible hybrids. When tissue from either resistant or susceptible plants that had been infested with either insect in the field was used in bioassays, larval weights were further reduced. It appears that both constitutive and induced defensive mechanisms may be operating.
The family Cecidomyiidae is one of the largest in the order Diptera. Gall midges are small, inconspicuous flies, but they may be very important both in forest ecosystems and in agroecosystems. The presently known fauna of gall midges in Turkey includes 71 species belonging to 38 genera. Forest gall midge (Diptera: Cecidomyiidae) fauna of Turkey was examined to determine that the composition consists of 33 species in 24 genera from 34 host tree species representing 15 tree genera. Of these, 31 species are phytophagous, 1 species is zoophagous, and 1 species is phytosaprophagous.
The lesser peach tree borer, Synanthedon pictipes (LPTB), belongs to the economically important Lepidopteran family Sesiidae. No studies on genetic variation or population structure on the genus Snyanthedon have been previously published. We examined DNA sequence variation in a 603 bp region of the mitochondrial cytochrome oxidase I gene (COI), tRNA-leu and cytochrome oxidase II gene (COII) from three LPTB populations in Arkansas. From 114 LPTB collected from three populations, a total of 53 nucleotide positions were polymorphic, and 12 distinct haplotypes were observed. The most frequent haplotype occurred in 88% of the sampled LPTB's and in all three populations. Sequence divergence among haplotypes ranged from 0.2% to 8.8%. According to the standard molecular clock proposed for lepidopteran mtDNA, the haplotypes have been diverging for up to 2.5 million years. The greatest amount of haplotype diversity was observed in the Fayetteville population where borer management is not maintained. High levels of gene flow were observed among the Clarksville, Springdale and Fayetteville populations suggesting the LPTB has a broad dispersal range. Examination of the genealogical relationships and phylogenetic analysis of the 12 haplotypes supports the existence of three genetically distinct but morphologically indistinguishable subspecies.
The papaya mealybug, Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae), is recorded from the Oriental Region for the first time, where it was found in Indonesia (Java) and India (Tamil Nadu) in 2008. Papaya mealybug is a polyphagous pest that damages many tropical crops. A native of Central America, it spread to the Caribbean region and South America in the 1990s; since then it has been accidentally introduced to some islands in the Pacific region. The distribution, host range and characteristics of the mealybug are summarized.
Cimex lectularius L. is a widespread hematophagus insect pest around the world and is currently experiencing a reemergence as a public health pest of concern. One possible source of bed bugs to the human environment is the movement of bed bugs from poultry facilities to human structures by poultry workers. No recent studies have been conducted on the susceptibility of this insect to a wide range of insecticides. In addition, populations of bed bugs from poultry facilities have not been screened against insecticides for over 15 yr. Adult bed bugs collected from three poultry facilities in northwest Arkansas were exposed for 24 or 48 h (25°C) to glass vials treated with various dilutions of 12 insecticides dissolved in acetone to determine the concentration–response relationship. The order of toxicity, from most to least based on the LC50s was: λ-cyhalothrin, bifenthrin, carbaryl, imidacloprid, fipronil, permethrin, diazinon, spinosyn, dichlorvos, chlorfenapyr, and DDT. Significant differences in LC50 and LC90 values for diazinon was observed among the three populations due to the previous history of repeated exposure to a mixture of tetrachlorvinphos and dichlorvos over a 10 yr period when compared to the LC50s of two populations that had been exposed to the tetrachlorvinphos and dichlorvos mixture during 2–3 flock cycles. Bed bugs in each of the three populations exhibited high levels of DDT resistance, LC50 > 100,000 ppm, which confirms that resistance to this insecticide continues in bed bug populations. This study documents baseline toxicological data for 12 insecticides in three populations of bed bugs and provides the first data on bed bug susceptibility to fipronil, spinosyn, and imidacloprid.
The influence of an early season production system (ESPS) on the population of bean leaf beetle (BLB), Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), adults and associated incidence of bean pod mottle (BPM) disease in soybeans was investigated in Mississippi. Early season production systems consist of planting maturity groups III or IV soybeans in mid-March to mid-April in the mid-South of the United States. Treatments in this study included early-planted and late-planted maturity group IV and maturity group V soybeans. Populations of adult BLB, a vector of bean pod mottle virus, were greater in ESPS in 2001, but no difference between planting dates was recorded in 2000. Incidence of BPM was greater in early-planted soybeans in 2000. The greater number of BLB adults in the early-planted soybeans did not result in a greater incidence of BPM disease in the ESPS in 2001. Yields in all treatments were significantly different with the greatest yield in the early-planted, maturity group V soybeans in 2000. In 2001, the greatest yield was obtained from late-planted, maturity group IV soybeans. The results presented herein suggest that to further evaluate relationships between bean leaf beetle vector populations and incidence of bean pod mottle disease in comparisons of conventional soybean production systems with ESPS, experiments should consider a wider range of soybean maturity groups and larger experimental plots to more effectively evaluate differences among soybean varieties and minimize beetle dispersal and spread of bean pod mottle disease.
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