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A lagarta rosca Agrotis ipsilon (Lepidoptera: Noctuidae) é uma praga polífaga que ataca mais de uma centena de tipos de cultivos. O hábito de ficar enterrada ou abaixo dos restos culturais pode ajudar o contato com nematoides entomopatogênicos (NEP), que são inimigos naturais de insetos. O objetivo deste estudo foi avaliar a persistência da patogenicidade de Steinernema carpocapsae e S. feltiae (Rhabditida: Steinernematidae), aplicados no solo contra lagartas de A. ipsilon. Os NEPs foram aplicados em vasos contendo solo e lagartas de A. ipsilon foram introduzidas nos vasos em cinco períodos (0, 2, 4, 6, e 8 dias após o tratamento). As duas espécies de NEPs causaram patogenicidade em todos os períodos avaliados. A taxa de mortalidade foi superior a 92% em todos os tratamentos e períodos.

The black cutworm Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae) is a cosmopolitan and polyphagous pest that attacks diverse crops and weed. One of the alternatives to insecticides may be the use of bioinsecticides based on Bacillus thuringiensis Berliner (Bt). Thus, the objective of the present study were evaluating the toxicity of Agree® and Dipel® bioinsecticides based on Bt on different larval ages of A. ipsilon. For the experiments, five larval ages were used (0-24, 48-72, 96-120, 144-168, and 192-216 h). The A. ipsilon caterpillars were individualized in acrylic tubes containing an artificial diet and 50 μL of each biopesticide in the concentration 1 × 108 spores mL-1. Mortality was assessed for seven days. The two bioinsecticides evaluated promoted mortality at all larval ages of A. ipsilon. The age of 0-24 h had mortality above 90%. The values of LC50 and LC90 were 9.8 × 105 and 7.4 × 106 spores mL-1 for Agree® and 1.3 × 106 e 1.4 × 107 spores mL-1 for Dipel®, respectively, without difference between LC50 and LC90 values of the bioinsecticides. The results indicate that younger caterpillars are more susceptible to Bt-based bioinsecticides.

Abstract: The objective of this work was to determine the functional response of the parasitoid Trichogramma pretiosum on Trichoplusia ni eggs at different temperatures (20, 25, and 30ºC) and egg densities (5, 10, 15, 20, 25, and 30 eggs). The logistic regression showed a type-II functional response for all temperatures. The search efficiency of T. pretiosum was reported as 0.049±0.0019, 0.069±0.0042 and 0.068±0.0033 per hour, and the estimated handling times were 1.82±0.0424, 1.69±0.0398, and 1.54±0.0498 hour at 20, 25 and 30ºC, respectively. Females of Trichogramma pretiosum show greater efficiency at 30ºC and a type-II functional response. The parasitism rate decreases, when host density increases.

The European pepper moth Duponchelia fovealis (Zeller, 1847) (Lepidoptera: Crambidae), despite being among the principal pests of strawberries in Brazil. However, biological control methods are rarely documented for this pest. In the current study, the goal was to select promising Trichogramma strains to enable the control of D. fovealis and to determine the acceptance of different ages of host eggs by the parasitoid. In the first bioassay, evaluations were done on the biological parameters of five strains of Trichogramma pretiosum Riley and one of Trichogramma galloi Zucchi (Hymenoptera: Trichogrammatidae). The best performance came from the strains, Tp18 (T. pretiosum) and Tg (T. galloi), showing parasitism and viability higher than 50 and 90%, respectively. Another bioassay revealed the acceptance of both these species (Tp18 and Tg) for different ages of D. fovealis eggs. All host ages were accepted by T. pretiosum (Tp18) and T. galloi, with a preference for younger eggs (65% parasitism). Adult emergence, number of individuals per egg and sex ratio revealed no significant differences with respect to the host age. The current study provides pertinent data on the selection and performance of Trichogramma species on D. fovealis eggs of different ages.