The evaluation of anti juvenile hormones using last stadium larvae of the cabbage looper,Trichoplusia ni (Hübner)

Treatment of prepupae of the cabbage looper, Trichoplusia ni (Hübner), with the anti juvenile hormone (AJH) fluoromevalonolactone (FMev) reduces juvenile hormone esterase (JHE) activity and either delays or inhibits the normal larval-pupal ecdysis in a dose-dependent manner, resulting in the formation of pupae with a suite of characteristic abnormalities. A variety of putative AJHs were evaluated using these teratogenic effects and changes in JHE activity as indicators of AJH activity. Like FMev, the compactin analog L-643,049-01K01 and, at very high doses, 3,3-dichloro-2-propenyl hexanoate (DPH) behaved as AJHs. FMev and L-643,049-01K01 were most effective when larvae were treated at gut purge, while DPH was the most effective after the initiation of spinning behavior.     

External antennal morphometry of Trichoplusia Ni (Hübner) (Lepidoptera: Noctuidae)

A detailed morphometric analysis of the antennae of male and female Trichoplusia ni (Hübner) is presented, based on light and scanning electron microscopic observations. These measurements of general antennal dimensions and the number, distribution, dimensions, and surface features of the antennal sensilla are applied in the consideration of olfactory transduction processes and in the derivation of a mathematical representation of the antennal surface. The surface area and the number of sensilla on the antennal flagellum are found to vary with the weight of the pupa and adult moth. The long Type 1 sensilla trichodea are hypothesized to be innervated by pheromone-sensitive olfactory cells on the basis of morphological comparisons with sensilla of other insects.     

Taxonomy and biogeography of the Nearctic Raphia Hübner (Lepidoptera,Noctuidae, Raphiinae)

The taxonomic status and biogeography of the North American Raphia species is reviewed using adult morphology, larval host plants, geographic phenotypic variation, and variation of mtDNA COI barcode sequences. Lack of diagnostic morphological differences, combined with relatively low mtDNA barcode divergences and clinal phenotypic variation in key geographic regions indicate that the six previously recognized species of North American Raphia are best interpreted as parapatric subspecies. Raphia frater abrupta Grote, stat. n., R. f. coloradensis Putnam-Cramer, stat. r., R. f. piazzi Hill, stat. n., and R. f. elbea Smith, stat. n., are accordingly revised to subspecies of R. frater Grote. Type locality restrictions are provided for Raphia abrupta and Raphia frater and a neotype is designated for Raphia frater var. coloradensis.     

First record of Peridroma saucia Hübner (Lepidoptera: Noctuidae) in transgenic soybeans

The widespread cultivation of transgenic soybeans has caused significant changes in the spectrum of Lepidoptera larvae, both in the number of species as well as on their densities in the field. Transgenic crops producing Bacillus thuringiensis (Bt) insecticidal proteins have successfully reduced the incidence of the most common caterpillars infesting soybeans, namely Anticarsia gemmatalis (Lepidoptera: Erebidae) and Chrysodeixis includens (Lepidoptera: Noctuidae). However, lepidopteran species not previously recorded on the crop have been recently found, and are of concern due to the possibility of adaptation to the genetically modified cultivars. The occurrence of Peridroma saucia Hübner (Lepidoptera: Noctuidae) is described for the first time in Brazil feeding on genetically modified soybean cultivars.     

Fecundity and life table parameters of Campoletis sonorensis (Hymenoptera: Ichneumonidae), an endoparasitoid of the Cabbage Looper Trichoplusia ni Hübner (Lepidoptera: Noctuidae), under laboratory conditions

The fecundity and life table parameters of Campoletis sonorensis females were measured using thirty 4-day-old Trichoplusia ni larvae daily at 24°C, 60% RH and a photoperiod of 12 h L:12 h D. The mean longevity was 34.5±2.8 days, the mean oviposition period was 22.7±1.9 days, and the mean constant oviposition period and the mean post-oviposition period were 15.9±1.3 and 11.9±2.2 days, respectively. The mean realised fecundity and the mean fertility differed significantly at 66.9±7.8 and 60.4±7.8 parasitoids per female, respectively. The mean sex ratio for the mean oviposition period (23 days) was 0.13±0.07, indicating a highly female biased ratio. The life table parameters were: intrinsic rate of natural increase (r _m), 0.135 female/day; gross reproductive rate (GRR), 50.30; net reproductive rate (R _o), 49.96; finite capacity for increase (λ), 1.14 female/day; mean generation time (T), 28.97 days; doubling time (DT), 5.13; capacity for increase (r _c), 0.33; and cohort generation time (T _c), 11.69. Campoletis sonorensis may be a suitable candidate for a biocontrol program of T. ni populations mostly because the primary selection criterion, r_m , obtained for this parasitoid can be similar to or larger than the rate obtained for T. ni.     

A new species of Schinia Hübner from the southeastern United States (Lepidoptera, Noctuidae, Heliothinae)

Schinia psamatheasp. n. is described from the southern coastal plain in Georgia and the East Gulf coastal plain in Florida and Alabama in habitats associated with sandy soil or dunes. Adult males and females and their genitalia are described and illustrated. Schinia psamathea is compared to Schinia saturata (Grote).     

Effect of the insect parasite Hyposoter exiguae (Viereck) on the carbohydrate metabolism of its host,Trichoplusia ni (Hübner)

Parasitization of Trichoplusia ni by Hyposoter exiguae resulted in elevations in the haemolymph trehalose concentration and fat body glycogen level. These increases in tissue carbohydrate reserves were accompanied by an elevation in the maximal velocities of fat body phosphofructokinase and fructose 1,6 bisphosphatase. The activity of the latter, however, was several-fold greater than that of phosphofructokinase and the potential gluconeogenic flux through the fructose phosphate step was, therefore, markedly increased following parasitization. The changes in adenylate levels in parasitized fat body, specifically an increase in AMP and decrease in ATP, were consistent with an elevation in phosphofructokinase activity in vivo but not in fructose 1,6 bisphosphatase activity. The latter enzyme, however, was shown to be less sensitive to both AMP and fructose 2,6 bisphosphate inhibition in fat body of parasitized individuals. Decreased haemolymph glucogenic amino acid concentrations and an increase in faecal uric acid level accompanied the above effects. It was concluded that parasitization of T. ni by H. exiguae caused a stress-induced hyperglycemia that may result from an alteration in the hormonal regulation over carbohydrate synthesis.     

Do different casein concentrations increase the adverse effect of rutin on the biology of Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae)?

The flavonoid rutin is recognized as playing an important role in the protection of plants against lepidopterans. Bioassays with this compound are generally carried out using artificial diets. Proteins of high energy value, such as casein, are important ingredients of insect artificial diets as a source of essential amino acids. However, such proteins can generally increase the allelochemical activity. Our objective was to evaluate the effects of rutin on larvae of the velvetbean caterpillar Anticarsia gemmatalis Hübner by incorporating this allelochemical into diets with different concentrations of casein. Three casein concentrations (0, 7 g, or 14 g) combined with none, 0.65%, or 1.30% of rutin were added to the rearing diet and offered to the larvae from hatching to pupation. Rutin negatively affected larval development, the amount of food consumed, and pupal weight of A. gemmatalis. These negative effects were clearly seen in insects fed on diets with 7 g of casein to which any concentration of rutin was added. The effects of rutin when added to the diets without casein were stronger than in diets containing a suitable amount of casein (14 g). The greater negative effects of rutin in diets containing suboptimal concentrations of casein indicate that casein can increase the effects of rutin only when the diets are nutritionally unsuitable for insect development.     

Modeling Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) damages on cotton

We studied and modeled damage caused by Helicoverpa armigera larvae on cotton with the aim of developing a coupled crop pest model. Two damage components were studied: the voracity (quantity of fresh matter and number of organs consumed) and feeding preferences (type of organ infested). The laboratory no-choice study of voracity on excised squares and bolls revealed that an H. armigera larva consumes 2,856 mg of fresh matter throughout its larval life, with the sixth instar consuming 86% of this quantity. This consumption rate corresponded to 23.6 squares, or 7.8 bolls. We developed equations to predict the quantity of fresh matter uptake from an individual plant organ, according to the organ mass and the larval instar. The field study of feeding preference confirmed previous findings that larvae prefer squares to bolls, with this preference decreasing as the larval age increases. However, no significant relationship was noted between the age of larvae and the size of infested organs within each organ class (square or boll). We developed a logistic model to predict the probability of a larva infesting a boll rather than a square. According to this model, the relative organ availability in the field and the larval instar were found to be significant factors.     

External morphology of the eggs of the meal moth,pyralis farinalis (L.), and the murky meal moth,Aglossa caprealis (Hübner) (Lepidoptera: Pyralidae)

The eggs of the meal moth, Pyralis farinalis (L.), and the murky meal moth, Aglossa caprealis (Hübner), were studied by scanning electron microscopy and diagnostic features determined. Eggs of P.farinalis are marked by a reticulate pattern of closely spaced sinuous ridges. The ridges are traversed by carinae that form a more or less continuous network over the entire surface of the egg. The cell discs and ridges are roughened by numerous minute rounded excrescences of the surface. The aeropylar openings are surrounded by double collars. Eggs of A. caprealis are marked by a reticulate pattern of polygons formed by intersecting ridges and carinae. The carinae zigzag along the ridges and form a continuous network over the entire surface. The cell discs are broad and densely marked by minute pits. The aeropylar openings are surrounded by single collars.     

Binding of Insecticidal Crystal Proteins of Bacillus thuringiensis to the Midgut Brush Border of the Cabbage Looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), and Selection for Resistance to One of the Crystal Proteins

The susceptibility of Trichoplusia ni larvae to several Bacillus thuringiensis insecticidal crystal proteins (ICPs) was tested. Neonatal larvae proved to be susceptible to solubilized trypsin-treated CryIA(a), CryIA(b), and CryIA(c) (50% lethal concentrations [LC(50)s], 570, 480, and 320 ng/cm, respectively) but showed little susceptibility to CryIB and CryID (LC(50)s, 5,640 and 2,530 ng/cm, respectively). The toxicity of ICPs was correlated to binding to the epithelial brush border of the midgut, as revealed by immunocytochemical staining with monoclonal antibodies. In vitro binding experiments with iodinated ICPs and brush border membrane vesicles indicated that CryIA(b) and CryIA(c) share the same high-affinity binding site, whereas CryIA(a) binds to a different one. The affinities of CryIA(b) and CryIA(c) for the binding site were similar (K(d) = 3.6 and 4.7 nM, respectively), and the mean binding-site concentration was 0.71 pmol/mg of vesicle protein. Selection of a population with increasing concentrations of CryIA(b) produced 31-fold resistance in seven generations. The realized heritability (h) was 0.19. The increase of homozygosity (for resistance factors) as selection proceeded was reflected in the increase in the slopes of the dose-mortality curves. Resistance was specific for CryIA(b) and did not extend to CryIA(a) or even to CryIA(c). This result was not predicted by the binding-site model, in which CryIA(b) and CryIA(c) bind to the same high-affinity binding site. This result may suggest a more complicated relationship between in vitro binding of ICPs to specific sites in the epithelial membrane of the midgut and the in vivo toxic effect.     

Organophosphorus insecticides synergize pyrethroids in the resistant strain of cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) from West Africa

Helicoverpa armigera (Hübner) populations from West Africa recently developed resistance to pyrethroid insecticides through enhanced metabolism by mixed-function oxidases. The combination index method was used to study the synergism of pyrethroids by organophosphorus insecticides. Several mixtures of insecticides currently registered to control cotton pest complex in West Africa were tested, including: cypermethrin/ethion, cypermethrin/profenofos, deltamethrin/ triazophos, deltamethrin/chlorpyriphos, cyfluthrin/chlorpyriphos, and betacyfluthrin/chlorpyriphos. In the resistant strain, the organophosphorus insecticides significantly increased the toxicity of pyrethroids suppressing the resistance effect, either by additive or synergistic effects. Significant synergism was shown for the following mixtures: cypermethrin/ethion, deltamethrin/triazophos, and deltamethrin/chlorpyriphos. The use of synergism from these insecticide mixtures should prove to be an additional tool in the overall resistance management strategy because the pyrethroid resistance in H. armigera from West Africa is not yet stable, decreasing between cotton seasons and increasing with treatments. In absence of selection, the susceptibility of H. armigera to insecticides should be restored.     

Genetic basis of sex pheromone blend difference between Helicoverpa armigera (Hübner) and Helicoverpa assulta (Guenée) (Lepidoptera: Noctuidae)

The two closely related moth species, Helicoverpa armigera and H. assulta, are sympatric in China. Both species use a mixture of (Z)-11-hexadecenal (Z11-16:Ald) and (Z)-9-hexadecenal (Z9-16:Ald) as their sex pheromones but in widely different ratios. Hybridization and backcrossing experiments between H. armigera and H. assulta were conducted and sex pheromone compositions of the parent species, their F(1) hybrids and backcrosses were compared to study the genetic basis of the production of their sex pheromone blend composition. Results show that the difference in sex pheromone blend ratios of these Helicoverpa species is mainly controlled by an autosomal locus with two alleles, with the allele from H. armigera being almost completely dominant over that derived from H. assulta.     

Ultrastructure of the larval stemmata,the stemmata nerves and the optic neuropils of the larval cotton bollworm,Heliothis armigera (Hübner) (Lepidoptera : Noctuidae)

Ultrastructure of stemmata (larval eyes), stemmatal nerves, and the optic neuropils of 5th-instar larvae of cotton bollworm, Heliothis armigera (Hübner) (Lepidoptera : Noctuidae), were examined with scanning and transmission electron microscopes. Six stemmata are on each side of the head. Each stemma consists of 7 retinula cells arranged into 2 tiers. Stemmata I and II have 4 distal retinula cells and 3 proximal cells, the other 4 stemmata (III–IV) have 3 distal cells and 4 proximal cells. Stemmata I and IV have a short proximal rhabdom and the rhabdomere of each proximal cell has its microvilli projecting in only one direction. On the other hand, each stemma (in stemmata II–V) has a long proximal rhabdom and the rhabdomere of each proximal cell has microvilli pitched in several different directions relative to the horizontal plane. An axon projects proximally from each retinula cell body. The stemmatal nerve is composed of the 42 retinular axons from all of the 6 stemmata on the same side of the head. Each stemmatal nerve projects to the ipsilateral optic neuropil. Axons from each stemma are in a fasicle (within the stemmatal nerve), which consists of 7 axons, 3–4 of them are thick and terminate synaptically in the proximal neuropil; the others are thinner and terminate in the distal neuropil. Organelles, particularly lysosomes, undergo ultrastructural transformations relative to ambient light levels. The functional significance of abovementioned structures are discussed in light of current knowledge.     

Effect of the populations of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) on cotton crop at two sowing distances

The objective of this research was to evaluate the incidence of damage by the leafworm Alabama argillacea (Hübner) on yields of cotton grown under rows spaced 0.38 m and 0.76 m at the irrigation area of Santiago del Estero, Argentina. The period evaluated was extended from first flower to first open boll. Treatments were T1 - without control of larvae, T2 - with control of larvae, T3 - control since first flower to the end of effective blooming, and T4 - with larval control since the end of effective blooming to first open boll. The effect of injuries on the crop was evaluated trough boll cotton yield. Larvae were sampled in a weekly basis and insects were present from the first flower until harvest. Populations of A. argillacea decreased crop yields in the two distances tested, by decreasing the weight or number of open bolls.     

Joint toxicity of methoxyfenozide and lufenuron on larvae of Spodoptera exigua Hübner (Lepidoptera: Noctuidae)

The joint action and sublethal effects of methoxyfenozide and lufenuron were measured against Spodoptera exigua. Methoxyfenozide and lufenuron exhibited optimum synergistic toxicity on S. exigua at a mass ratio of 4:6, and the co-toxicity coefficient (CTC) was 165.705. Third instars larvae of S. exigua were treated with methoxyfenozide (LC₁₅ = 21.004 ng/cm²), lufenuron (LC₁₅ = 27.134 ng/cm²), or a mixture of methoxyfenozide and lufenuron (MML, LC₁₅ = 16.503 ng/cm²) through feeding for 72 h. Ingestion of MML by larvae significantly inhibited larval and pupal weights and pupation rate, and prolonged the larval and pupal development of S. exigua compared to individual treatment ofmethoxyfenozide or lufenuron. Both methoxyfenozide and MML treatments significantly decreased the fertility of female S. exigua. No significant changes were observed in case of adult emergence and egg hatching for different treatments. The MML-treated S. exigua exhibited significantly lower activities of polyphenol oxidase (PPO) and cytochrome P450 (CYP450) than those in S. exigua treated separately with methoxyfenozide or lufenuron. Finally, methoxyfenozide, lufenuron, and MML treatments decreased chitinase, acetylcholinesterase (AChE), carboxylesterase (CarE), and glutathione-s-transferase (GST) activities in S. exigua.     

Anatomy of the neurosecretory cells in the cerebral and subesophageal ganglia of the female European corn borer moth,Ostrinia nubilalis (Hübner) (Lepidoptera: Pyralidae)

The anatomy of the neurosecretory cells in the brain-subesophageal ganglion complex of female European corn borer moth Ostrinia nubilalis (Lepidoptera: Pyralidae) was studied using histological and cobalt backfilling techniques. Histological staining revealed the presence of 2 median and one lateral neurosecretory cell groups in the brain. These brain neurosecretory cells are made up of mainly type A cells with a few type B cells in the median group. Three type C neurosecretory cell clusters occupy the apparent mandibular, maxillary, and labial neuromeres at the ventral median aspect of the subesophageal ganglion. Axonal pathways of the neurosecretory cell groups were delineated by retrograde cobalt filling from the corpora cardiaca. Fibers of the 3 brain neurosecretory cell groups merged to form a distinct axonal tract that exits the brain via the fused nervi corporis cardiaci-1 + 2. Cobalt backfilling from the corpora cardiaca filled 4 groups of cell bodies in the subesophageal ganglion. The presence in the subesophageal ganglion of extensive dendritic arborizations derived from the brain suggests interactions between neurosecretory cell groups in the 2 head ganglia.