The establishment of cell lines from imaginal wing discs of Spodoptera frugiperda and Plodia interpunctella

Continuous cell cultures were established from imaginal wing discs of 2 Lepidoptera, Spodoptera frugiperda and Plodia interpunctella. The S. frugiperda line (IAL-SFD1) grows as multicellular vesicles and responds morphologically and biochemically to the insect hormone, 20-hydroxyecdysone. In contrast, the P. interpunctella cells (IAL-PID2) grow as attached monolayers of small spindle-shaped cells and do not appear to have specific responses to 20-hydroxyecdysone, although growth rates are slowed in these cells upon exposure to the hormone.     

Pharmacokinetics of chlorogenic acid and rutin in larvae of Heliothis zea

Studies using [³H]chlorogenic acid and [³H]rutin demonstrated that the kinetics of uptake of these plant phenolics into the haemolymph of 5th-instar Heliothis zea (Boddie) following actue oral administration is a first-order process. The total quantity of either phenolic present in the haemolymph within 1 hr amounts to 5% or less of the total ingested dose. Based on TLC analyses, 80% or more of the radioactivity in the haemolymph occurs as the parent phenolic. Retention of [³H]-chlorogenic acid or [³H]-rutin in H. zea following chronic feeding from 1st to 3rd-instar larvae is also linearly related to dietary dose. Chlorogenic acid and rutin are both equitoxic and equivalent in bioavailability to H. zea.Loss of [³H]-rutin from the haemolymph of 5th-instar larvae following injection is biphasic. One half of the injected dose is excreted in the frass in the first 6 hr after injection; the other half is thereafter eliminated at 1/20th of the initial rate. Analyses of extracts of frass by thin-layer chromatography indicate that after either chronic or acute feeding 90% of the ingested phenolic is excreted unchanged. Possible sites and modes of action of phenolics in insects are discussed in light of these findings.     

Redescription of Heterodea zeae,the Corn Cyst Nematode,with SEM Observations

Heterodera zeae, the corn cyst nematode, is redescribed and illustrated with comparative details and measurements of females, cysts, and larvae from Maryland, USA; and India. Scanning electron micrographs o f specimens from the United States are also presented. Revised measurements for the larval stylet and new diadnostic characters, especially in the cyst cone, for H. zeae are given. The relationship of H. zeae to close species is discussed.     

Description of Thecavermiculatus andinus n.sp. (Meloidoderidae), a Round Cystoid Nematode from the Andes Mountains of Peru

Thecavermiculatus andinus n.sp. is described and illustrated from Oxalis tuberosa originally collected in the vicinity of Lake Titicaca high in the Andes mountains of southern Peru. This new species differs markedly front the other two species in the genus, especially in having a much greater female vulval-anal distance and annules with lined punctation on most of the female body with a lacelike pattern restricted to the posterior portion, particularly at the vulva and anus which do not protrude. Females are essentially spherical with protruding neck, white to yellowish in color, and can easily be mistaken for potato cyst nematodes. Among the dozen or more known weed and crop host plants are potato and eggplant. In order to accommodate this new species, the genus Thecavermieulatus is emended. A key to the species of this genus is presented.     

Meloidogyne enterolobii n. sp. (Meloidogynidae), a Root-knot Nematode Parasitizing Pacara Earpod Tree in China

Meloidogyne enterolobii n. sp. is described and illustrated from roots of pacara earpod tree, Enterolobium contortisiliquum (Vell.) Morong, on Hainan Island in China. The perineal pattern of the female is usually oval shaped, the striae are fine to coarse, the dorsal arch is moderately high to high and usually rounded, and the phasmids are large. The stylet knobs in females are divided longitudinally by a groove so that each knob appears as two. The mean distance of the excretory pore to the anterior end in the female is 62.9 μm. Males have a large, rounded labial disc that fuses with the medial lips to form a dorso-ventrally elongate head cap. The labial disc is slightly elevated, and the medial lips are crescent shaped. The second-stage juvenile mean body length is 436.6 μm. The lateral lips are large and triangular in face view. The tail is 56.4 μm long and narrow with a broad, bluntly rounded tip. M. enterolobii n. sp reproduces well on E. contortisiliquum and causes severe damage. Other good hosts include cotton, resistant tobacco ''NC 95,'' pepper, watermelon, and tomato.     

Interaction of Vesicular-arbuscular Mycorrhizal Fungi and Phosphorus with Meloidogyne incognita on Tomato

The influence of two vesicular-arbuscular mycorrhizal fungi and phosphorus (P) nutrition on penetration, development, and reproduction by Meloidogyne incognita on Walter tomato was studied in the greenhouse. Inoculation with either Gigaspora margarita or Glomus mosseae 2 wk prior to nematode inoculation did not alter infection by M. incognita compared with nonmycorrhizal plants, regardless of soil P level (either 3 μg [low P] or 30 μg [high P] available P/g soil). At a given soil P level, nematode penetration and reproduction did not differ in mycorrhizal and nonmycorrhizal plants. However, plants grown in high P soil had greater root weights, increased nematode penetration and egg production per plant, and decreased colonization by mycorrhizal fungi, compared with plants grown in low P soil. The number of eggs per female nematode on mycorrhizal and nonmycorrhizal plants was not influenced by P treatment. Tomato plants with split root systems grown in double-compartment containers which had either low P soil in both sides or high P in one side and low P in the other, were inoculated at transplanting with G. margarita and 2 wk later one-half of the split root system of each plant was inoculated with M. incognita larvae. Although the mycoorhizal fungus increased the inorganic P content of the root to a level comparable to that in plants grown in high P soil, nematode penetration and reproduction were not altered. In a third series of experiments, the rate of nematode development was not influenced by either the presence of G. margarita or high soil P, compared with control plants grown in low P soil. These data indicate that supplemental P (30 μ/g soil) alters root-knot nematode infection of tomato more than G. mosseae and G. margarita.     

Histopathology of Selected cultivars of Tobacco infected with Meloidogyne species

Rates of nematode penetration and the histopathology of root infections in fluecured tobacco cultivars ''McNair-944,'' ''Speight G-28,'' and ''NC-89'' with either Meloidogyne arenaria, M. incognita, M. hapla, or M. javanica were investigated. Penetration of root tips by juveniles of all species into the M. incognita-resistant NC-89 and G-28 was much less than that on the susceptible McNair-944. Few juveniles of M. incognita were detected in resistant cultivars 7 and 14 days after inoculation. Infection sites exhibited some cavities and extensive necrotic tissue at 14 days; less necrotic tissue and no intact nematodes were observed 35 days after inoculation. Although some females of M. arenaria reached maturity and produced eggs, considerable necrosis was induced in the resistant cultivars. Meloidogyne hapla and M. javanica developed on all cultivars, but there was necrotic tissue at some infection sites in the resistant cultivars. The occurrence of single multistructured nuclei in the syncytia of most M. hapla infections differed from the numerous small nuclei found in syncytia caused by the other three species.     

Use of Avermectins for the Control of Meloidogyne incognita on tomatoes

The efficacy of avermectins B₁ and B₂ for control of Meloidogyne incognita on tomato was studied in pots and field plots for two seasons. Avermectins were applied as granules and liquid in furrows or by low pressure drip irrigation systems, at rates ranging from 0.093 to 0.34 kg a.i./ha, as single or multiple applications. Levels of control comparable to those obtained by oxamyl and aldicarb at 3.36 kg a.i./ha were achieved by the avermectin with only 1/10 the volume of chemicals applied to the environment. Avermectin protection of the roots remained constant throughout the first 5 weeks giving slightly longer protection than oxamyl or aldicarb.     

Population Dynamics of Meloidogyne incognita and Rotylenchulus reniformis Alone and in Combination,and Their Effects on Sweet Potato

Meloidogyne incognita (Mi) and Rotylenchulus reniformis (Rr) interactions on sweet potato were studied in naturally and artificially infested field plots for 3 years. In a naturally infested field, early season counts of Mi or Rr were positively correlated with later counts of the same nematode, but negative correlations were found between early Mi and subsequent Rr, and early Rr and subsequent Mi counts. In field plots fumigated with methyl bromide and then infested with low levels of Rr, Mi, and Rr + Mi, final population densities of Mi juveniles were reduced by Rr, but Rr was not affected by Mi. In field plots with a high natural population density of Rr, artificial infestation with high levels of Mi in both fumigated and nonfumigated treatments inhibited Rr, while the final Mi juvenile population density was not affected. Results indicate that a competitive interaction exists with each species capable of inhibiting the other and becoming the dominant population. The nematodes had no apparent effect on yield at the inoculum densities used, either alone or mixed. Both nematodes increased cracking of sweet potatoes, but mixed populations did not differ in incidence of cracking from either Rr or Mi alone.     

1H nmr studies of complexes of ferric leghemoglobin with substituted pyridines and nicotinic acids

The ¹H nuclear magnetic resonance (nmr) spectra of complexes of soybean ferric leghemoglobin with 3-substituted pyridines and 5-substituted nicotinic acids have been recorded in order to determine the influence of axial ligands on heme electronic structure. The hyperfine shifted resonances of the heme group were assigned by analogy to previous assignments for the pyridine and nicotinic acid complexes of leghemoglobin. The spectra are characteristic of predominantly low-spin ferric heme complexes. For the pyridine complexes, the rate of ligand exchange was found to increase with decreasing ligand pK_A. For many of the complexes, optical and nmr spectra reveal the presence of an equilibrium mixture of high- and low-spin states of the iron atom. The percentage of high-spin component increases with decreasing ligand pK_A Smaller hyperfine shifts are noted for leghemoglobin complexes with ligands capable of weak ligand → metal π bonding. The pattern of hyperfine shifted resonances is similar for all complexes studied and indicates that the overall heme electronic structure is dominated by the bonding to the proximal histidine.