Trichogramma spp. (Hymenoptera: Trichogrammatidae) can control Diaphania hyalinata Linnaeus (Lepidoptera: Pyralidae). On the other hand, pesticides may reduce the efficiency of natural enemies. The objective was to evaluate the side-effects of fungicides used in the production of cucurbitaceous crops on Trichogramma atopovirilia Oatman & Platner parasitizing D. hyalinata eggs. The fungicides used in bioassays were: azoxystrobin (0.08 g active ingredient [ai] L-1), chlorothalonil (2.00 g ai L-1), mancozeb (1.60 g ai L-1), tebuconazole (0.25 g ai L-1) and thiophanate-methyl (0.49 g ai L-1). Cardboards with 30 D. hyalinata eggs previously immersedin fungicide solutions and distilled water (control) were offered separately to 20 newly emerged T. atopovirilia females in glass tubes. Parasitism, parasitism reduction, emergence, sex ratio, and number of individuals per egg were evaluated. The fungicides chlorothalonil, thiophanate-methyl and tebuconazole reduced parasitism of T. atopovirilia by 43.37, 27.64 and 18.51%, respectively. However, parasitism with azoxystrobin (79.21%) was higher than the control (67.37%) (P ≤ 0.05). Chlorothalonil, thiophanate-methyl and tebuconazole reduced emergence by 73.77, 75.62 and 79.35% (P ≤ 0.05), respectively. Azoxystrobin and thiophanate-methyl reduced the sex ratio by 0.77 and 0.76 (P ≤ 0.05), respectively. Fungicides did not reduce the number of individuals per egg. The fungicides azoxystrobin and mancozeb were selective for T. atopovirilia for most studied parameters suggesting that these products must have the priority in crop disease management to allow efficient biological control of T. atopovirilia against D. hyalinata.

Trichogramma spp. (Hymenoptera: Trichogrammatidae) pueden controlar Diaphania hyalinata Linnaeus (Lepidoptera: Pyralidae). Sin embargo, los plaguicidas pueden reducir la eficiencia de los enemigos naturales. El objetivo de este trabajo fue evaluar la influencia de los fungicidas utilizados en la producción de cucurbitáceas en Trichogramma atopovirilia Oatman & Platner sobre huevos de D. hyalinata. Se evaluaron los fungicidas azoxystrobina (0.08 g ingrediente activo [ia] L-1), clorotalonil (2.00 g ia L-1), mancozeb (1.60 g ia L-1), tebuconazole (0.25 g ia L-1) and tiofanato-metil (0.49 g ia L-1). Tarjetas con 30 huevos de D. hyalinata previamente sumergidos en los fungicidas y en agua destilada (control) fueron ofrecidas a 20 hembras de T. atopovirilia con hasta 24 h de emergencia individualizadas en tubos de vidrio. Se evaluó parasitismo, reducción de parasitismo, emergencia, proporción sexual en la población y el número de individuos emergidos por huevo. Los fungicidas clorotalonil, tiofanato-metil y tebuconazol redujeron el parasitismo de T. atopovirilia en 43,37; 27,64 y 18,51%, respectivamente. Sin embargo, el parasitismo con azoxistrobina (79,21%) fue mayor que el control (67,37%) (P ≤ 0,05). Clorotalonil, tiofanato-metilo y el tebuconazol redujo la aparición de 73,77, 75,62 y 79,35% (P ≤ 0,05), respectivamente. Azoxistrobina y tiofanato-metil reduciran la proporción de sexos de 0,77 y 0,76 (P ≤ 0,05), respectivamente. Ninguno de los fungicidas redujo el número de individuos por cada huevo. Los fungicidas azoxistrobina y mancozeb fueron selectivos para T. atopovirilia en la mayoría de los parámetros estudiados, por lo tanto, deberían tener prioridad en el manejo de enfermedades de cucurbitáceas para permitir el uso eficiente de los enemigos naturales de D. hyalinata.

A biologia de Trichogramma atopovirilia Oatman & Platner parasitando ovos de Diaphania hyalinata L. foi estudada nas temperaturas de 18, 21, 24, 27, 30 e 33ºC e suas exigências térmicas foram determinadas. Trinta ovos do hospedeiro foram submetidos ao parasitismo na proporção de uma fêmea do parasitóide para 10 ovos, durante 5h, a 25°C e incubados nas diferentes temperaturas. Os parâmetros avaliados foram duração do ciclo ovo-adulto, viabilidade, número de indivíduos emergidos por ovo e razão sexual. A duração do período de desenvolvimento ovo-adulto apresentou relação inversa à temperatura e foi de 24,12 dias a 18°C e 7,36 dias a 33°C. A viabilidade do parasitismo a 24, 27 e 30ºC foi superior a 90%. O número de indivíduos emergidos por ovo hospedeiro e a razão sexual não sofreram influência da temperatura. A temperatura base (Tb) e a constante térmica (K) requerida por T. atopovirilia criados em ovos de D. hyalinata foi de 11,99°C e 130,42°C, respectivamente. Baseado nas médias térmicas de duas localidades de cultivo de cucurbitáceas da Bahia (Rio Real e Inhambupe) estimou-se que T. atopovirilia pode completar mais do que 32 gerações ao longo do ano. Estes resultados indicam que T. atopovirilia possui potencial de utilização para o controle de D. hyalinata com maiores chances de sucesso entre as temperaturas de 24°C e 27°C as quais também são apropriadas para o cultivo de cucurbitáceas.

The development and parasitism of Diaphania hyalinata L. eggs by Trichogramma atopovirilia Oatman & Platner and its thermal requirements were studied at the temperatures of 18, 21, 24, 27, 30 and 33°C. Thirty eggs of D. hyalinata were exposed to three females of T. atopovirilia for 5h at 25°C and incubated at the different temperatures. The developmental time from egg exposure to adult, parasitism viability, number of adults per parasitized host egg and progeny sex ratio were monitored. The developmental time from egg to adult emergence of the parasitoid exhibited inverse relationship to the temperature, lasting 24.12 days at 18°C and 7.36 days at 33°C. Parasitism viability at 24, 27 and 30°C was higher than 90%. The ratio of T. atapovirilia adult produced per egg and its sex ratio were not affected when using D. hialynata as host. The lowest threshold temperature (Tb) and estimated degree-days over Tb required by T. atopovirilia to develop on eggs of D. hyalinata was 11.99°C and 130.42ºC, respectively. Considering the temperature regimes of two areas where cucurbitaces are cultivated in Bahia State (Rio Real and Inhambupe County) it was estimated that T. atopovirilia can achieve more than 32 generation per year. The results suggest that T. atopovirilia has potential to control D. hyalinata eggs with better chance of success under temperature regimes ranging from 24 to 27°C that meets the suitable field conditions for cropping cucurbitaces.