Two's a crowd: phenotypic adjustments and prophylaxis in anticarsia gemmatalis larvae are triggered by the presence of conspecifics.

2013

Nomuraea rileyi (Hypocreales: Clavicipitaceae) in Helicoverpa armigera (Lepidoptera: Noctuidae) Larvae in Brazil.

2015

Comparison of biology between Helicoverpa zea and Helicoverpa armigera (Lepidoptera: Noctuidae) reared on artificial diets.

The objective of this study was to compare growth and development of Helicoverpa zea Boddie and Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) larvae that were feeding on an artificial diet. Neonate larvae of H. zea and H. armigera were collected in maize fields cultivated at the Brazilian Agricultural Research Corporation, Embrapa Maize & Sorghum, in Sete Lagoas (Minas Gerais) and in farmers? cotton fields in Luís Eduardo Magalhães (Bahia), respectively. Bioassays were conducted in the laboratory using individual larvae in 50 mL plastic cups fed a white bean?based artificial diet and maintained at a temperature of 26 ± 2 °C and a relative humidity of 47 ± 10%. The following larval biological parameters were evaluated: number and duration of instars, survival of larval instars and pupae, larval biomass, larval head capsule size, and larval length. An adaptation index was computed for comparison of development of the 2 species. Significant differences were observed between the species for all variables except for the number of instars and pupal survival. Although H. armigera larvae developed faster and were smaller than H. zea larvae, the diet tested can be considered adequate for rearing both species in the laboratory.

Life-history traits of Spodoptera frugiperda populations exposed to low-dose Bt maize.

Exposure to Bacillus thuringiensis (Bt) toxins in low- and moderate-dose transgenic crops may induce sublethal effects and increase the rate of Bt resistance evolution, potentially compromising control efficacy against target pests. We tested this hypothesis using the fall armyworm Spodoptera frugiperda, a major polyphagous lepidopteran pest relatively tolerant to Bt notorious for evolving field-relevant resistance to single-gene Bt maize. Late-instar larvae were collected from Bt Cry1Ab and non-Bt maize fields in five locations in Brazil, and their offspring was compared for survival, development, and population growth in rearing environment without and with Cry1Ab throughout larval development. Larval survival on Cry1Ab maize leaves varied from 20 to 80% among the populations. Larvae reared on Cry1Ab maize had seven-day delay in development time in relation to control larvae, and such delay was shorter in offspring of armyworms from Cry1Ab maize. Population growth rates were 50?70% lower for insects continuously exposed to Cry1Ab maize relative to controls, showing the population-level effect of Cry1Ab, which varied among the populations and prior exposure to Cry1Ab maize in the field. In three out of five populations, armyworms derived from Bt maize reared on Cry1Ab maize showed higher larval weight, faster larval development and better reproductive performance than the armyworms derived from non-Bt maize, and one of these populations showed better performance on both Cry1Ab and control diets, indicating no fitness cost of the resistance trait. Altogether, these results indicate that offspring of armyworms that developed on field-grown, single-gene Bt Cry1Ab maize had reduced performance on Cry1Ab maize foliage in two populations studied, but in other three populations, these offspring had better overall performance on the Bt maize foliage than that of the armyworms from non-Bt maize fields, possibly because of Cry1Ab resistance alleles in these populations. Implications of these findings for resistance management of S. frugiperda in Bt crops are discussed.

Toxicity of pyrethroids and other insecticides against susceptible and resistant tobacco budworm larvae and synergism by chlordimeform.

1987

Histopathology from liver of tuvira (Gymnotus spp.) parasitized by larvae of nematodes.

Abstract: The aim of this study was to evaluate the histological changes in the liver of thirty-five Gymnotus spp. parasitized by endohelminths collected between April 2012 to October 2013 in commercial bait fish farming of Pantanal basin. Histological cuts of 7?m were stained with hematoxylin-eosin for parasites research and liver changes and have also been submitted to the Perls histochemical method for evaluation of hemosiderosis (Fe+++) based on the incidence degree and severity of change (Grade I, II and III) and tests for the presence of central melanomacrophages. Parasites identified were: Brevimulticaecum sp. with a prevalence of 22,9%, Eustrongylides sp 17,1%, Contracaecum type I 68,7%, Contracaecum type II 5,7%, Contracaecum type III 5,7% and larvae of Anisakidae 11,4%. Histological analysis showed intense disorganization of hepatic parenchyma with degenerate hepatocytes due to high parasitic infection, changes that can be deleterious and compromise the organism functioning, being harmful to the health of evaluated animals. Also evidencing normal tissue interleaved with different stages of Fe+++ deposit in grades II and III, injuring or destroing the cell. Histopathological changes in the tuvira?s liver suggested a chronic response and the development of a balance relation between tuvira and parasitism by endohelminth identified in this study. There are also a testimony to the health condition of commercial bait fish farming on current ecosystem conditions.

Basis for the Development of a Rearing Technique of Aganaspis pelleranoi (Hymenoptera: Figitidae) in Anastrepha fraterculus (Tephritidae: Diptera).

2016