The aim of this study was to assess the biological aspects and food preferences of Helicoverpa armigera fed different sunflower genotypes and an artificial diet. Tests were performed under multiple-choice and no-choice conditions to evaluate the biological characteristics of H. armigera. In addition, the biological data obtained were used to determine parameters of fertility life tables. The results showed that H. armigera does not have a feeding preference among the sunflower genotypes tested. The larval period on sunflower ranged from 15.0 to 16.2 days. The maximum fecundity on sunflower was 542.6 eggs/female and that on the artificial diet was 794.5 eggs/female. In general, insects feeding on Helio 250 consumed greater quantities of leaves, had higher survival until the end of the pupal stage, displayed high population growth rates, and had low population doubling times, suggesting that in the field populations will achieve greater population densities when fed on Helio 250. Insects that fed on CF101 consumed smaller leaf areas, had lower survival until the end of the pupal stage, lower fertility rates, and lower population growth rates, and may also have displayed lower population densities and smaller reductions in field productivity. This insect developed best on an artificial diet in comparison to sunflower genotypes studied.

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is a polyphagous pest with a wide geographic distribution. This pest first arrived in Brazil in 2013, and since then studies on possible control methods for it have been necessary. A possible method for the control of H. armigera is using the egg parasitoid Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae). Therefore, the objective of this study was to evaluate the performance of T. pretiosum on H. armigera eggs, which are known to represent suitable hosts for the development of this parasitoid species in the laboratory. Parasitism and emergence rates and the duration of the egg-to-adult period of T. pretiosum were investigated following 24- and 48-h exposures of this parasitoid to H. armigera and Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae) eggs. The longevity of offspring after the 24-h exposure was studied, as well as the frequency of parasitism and emergence, host preference, and the emergence of offspring from eggs of different ages or oviposited by lepidopterans on different days. Parasitism was 14.4 and 34.9% more frequent on C. cephalonica than on H. armigera after 24 and 48 h of exposure, respectively. In C. cephalonica, parasitism was 27.2% higher after 48 h. Parasitism was more frequent on C. cephalonica eggs collected on the second day of oviposition (76.2%), and on H. armigera on the third day of oviposition (71.1%). Parasitism frequency was lower on 2-day-old C. cephalonica eggs (63.3%) and on 3-day-old H. armigera eggs (41.3%). When tested with a chance of choice between hosts, T. pretiosum preferred H. armigera, while in the test with no chance of choice there was no difference in preference. Thus, T. pretiosum may be considered a tool for the Integrated Pest Management (IPM) of H. armigera.

ResumoO objetivo do trabalho foi avaliar diferentes dietas para lagartas de Diatraea saccharalis, com o intuito de obter informações sobre as características biológicas da praga e consequentemente avaliar a qualidade do parasitoide Cotesia flavipes, visando melhorar tecnicamente sua produção massal. Lagartas de 24 horas de idade foram transferidas para tubos (25 lagartas/ tubo) contendo dieta artificial com levedura de cerveja e germe de trigo e outra somente com germe de trigo como fonte de proteína. Depois de aproximadamente 15 dias, as lagartas foram retiradas dos tubos e acondicionadas em placas com dieta, sendo observadas lagartas de D. saccharalis não parasitadas e parasitadas para avaliação das características biológicas de D. saccharalis e C. flavipes nas diferentes dietas. Além da observação das características biológicas de D. saccharalis, foram realizadas medições nas lagartas de 15 dias de idade. Também, massas de pupas de C. flavipes produzidas em biofábrica foram classificadas em três diferentes tamanhos, sendo pequenas (1,3 a 2,5 cm de comprimento), médias (2,5 a 3,5 cm de comprimento) e grandes (3,5 a 4,0 cm de comprimento). Após a emergência dos adultos foi realizado o parasitismo em lagartas de D. saccharalis, sendo observados o número de machos e fêmeas, tamanho da massa, razão sexual e número de pupas inviáveis. A dieta artificial que contém somente germe de trigo é a mais indicada para criação massal do hospedeiro D. saccharalis para produção em larga escala de C. flavipes. Massas de pupas classificadas como grandes possuem melhor qualidade em criações massais de C. flavipes. Palavras-chave:Crambidae, broca-da-cana, controle biológico, cana-de-açúcar. Protein source in Diatraea saccharalis diet and its impact on production and quality control of Cotesia flavipes AbstractThe aim of this work was to evaluate different diets for Diatraea saccharalis larvae, obtaining information about the biological characteristics of the pest, and to evaluate the quality of Cotesia flavipes parasitoid, to improve mass rearing method. For the accomplishment of the experiment, 24 hour-old larvae were transferred to tubes (25 larvae/tube) containing artificial diets with yeast and wheat germ or just wheat germ as protein source. After approximately 15 days, the larvae were removed from tubes and placed in Petri dishes, being observed D. saccharalis larvae not parasitized and parasitized for evaluation of D. saccharalis and C. flavipes biological characteristics. Biological characteristics of D. saccharalis were also evaluated in 15 day-old larvae. Pupae mass of C. flavipes from mass rearing were classified in three different sizes separated in small (1.3 to 2.5 cm of length), moderate (2.5 to 3.5 cm of length) and large (3.5 to 4.0 cm of length) classes. After the adult emergency, the parasitism was evaluated in D. saccharalis larvae, being observed the number of males and females, size of pupae mass, sex ratio and number of unviable pupae. The artificial diet that contains wheat germ is the most suitable for D. ...

The diamondback moth (DBM), Plutella xylostella (L.), is a major pest of brassica crops worldwide. Control of this pest is difficult because it rapidly develops resistance to synthetic and biological insecticides and because of the effects of insecticides on its natural enemies. Podisus nigrispinus (Dallas) is a predator that feeds on its prey, as well as on the host plants of its prey, and is an important biological control agent of DBMs. The aim of this study was to determine the susceptibility of P. xylostella larvae to two bioinsecticides: the HD1 strain of Bacillus thuringiensis (B. thuringiensis var. kurstaki) and the commercial product Agree â (B. thuringiensis var. aizawai CG 91). In addition, the impact of these bioinsecticides on the P. nigrispinus consumption of DBM larvae and phytophagy was evaluated. Both the HD1 strain and Agree â caused 100% mortality in P. xylostella larvae.P. nigrispinus nymphs fed only with kale leaves (Brassica oleracea var. acephala) sprayed with water, the HD1 strain, or Agree â did not complete their nymphal development. When prey was also available, P. nigiripinus fed on kale leaves to obtain water. Both nymphs and adults of P. nigrispinus consumed greater numbers of DBM larvae, and fed less on kale leaves, when sprayed with the HD1 strain or Agree â . These results suggest a positive interaction of B. thuringiensis-based products and the predator P. nigrispinus in the control of P. xylostella larvae.

Helicoverpa armigera (Hübner) is an important pest of crops worldwide, and several studies have focused on the development of this species on different artificial diets. However, studies evaluating the insect’s food consumption and utilization using nutritionally different diets are scarce. The aim of this study was to evaluate the biology and to compare the consumption and use of food by H. armigera larvae on diets with different protein levels provided by several dietary ingredients used in the diets. The nutritional index, the relative consumption rate, the relative metabolic rate, the relative growth rate, and the apparent digestibility were higher in the diet with higher than the optimum level of protein. On the other hand, the conversion efficiency of digested food was lower, resulting in a higher metabolic cost. In terms of biological aspects, larval survival was higher for the diet with optimal protein content and lower for the diet with a higher protein level. The pupal period was longer for the diet with a higher protein content, while pupal survival was lower. Among the evaluated diets, the diet with an optimal protein containing white bean 75 g, wheat germ 60 g, soy bran 30 g, milk powder 30 g, brewer’s yeast 37.5 g as the protein sources resulted in a higher net reproductive rate, a shorter time for the population to double in number, and the highest rates of population growth. The results suggest that lower or higher protein contents in the diets of H. armigera negatively affect the biological aspects of this species.