Biological parameters and thermal requirements of Trichogramma pretiosum reared on Helicoverpa armigera eggs

Abstract

-The objective of this work was to determine the biological parameters and thermal requirements of Trichogramma pretiosum TM strain reared on Helicoverpa armigera eggs. A card containing 20 eggs of H. armigera was offered for each T. pretiosum female, at temperatures of 18, 20, 22, 25, 28, 30 and 32°C. All life stages of T. pretiosum were observed under the given temperature conditions. The optimum temperature for the parasitism of T. pretiosum was 25°C, and the highest longevity was found at the same temperature. The highest parasitoid emergence rates occurred at temperatures of 22, 25 and 28°C. The highest proportion of T. pretiosum individuals emerged per egg was observed at 18°C. Concerning the sex ratio, the highest proportion of females occurred at 28°C, and the highest percentage of parasitism viability was observed at this same temperature. The lowest thermal threshold for total preimaginal development and thermal requirements of T. pretiosum were 10.82°C and 134.55 degree-days, respectively. The estimated number of generations of T. pretiosum in the average temperatures of municipality of Bom Jesus, state of Piauí, Brazil is four per month.Index terms: Trichogrammatidae, biological control, parasitoid, temperature. Parâmetros biológicos e exigências térmicas de Trichogramma pretiosum sobre ovos de Helicoverpa armigera Resumo -O objetivo deste trabalho foi determinar os parâmetros biológicos e as exigências térmicas deTrichogramma pretiosum linhagem TM sobre ovos de Helicoverpa armigera. Para cada fêmea, foi oferecida uma cartela contendo 20 ovos de H. armigera, às temperaturas de 18, 20, 22, 25, 28, 30 e 32°C. Todos os estádios de vida de T. pretiosum foram observados sob as dadas condições de temperatura. A temperatura ótima para o parasitismo de T. pretiosum foi de 25°C e a maior longevidade foi verificada à mesma temperatura. As maiores taxas de emergência do parasitoide foram às temperaturas de 22, 25 e 28°C. A maior proporção de indivíduos de T. pretiosum emergidos por ovo foi observada a 18°C. Quanto à razão sexual, a maior proporção de fêmeas ocorreu a 28°C, e o maior percentual de viabilidade do parasitismo foi observado à mesma temperatura. O limiar térmico inferior para o desenvolvimento pré-imaginal total e as exigências térmicas de T. pretiosum foram de 10,82°C e 134,55 grau-dias, respectivamente. O número estimado de gerações de T. pretiosum às temperaturas médias do Município de Bom Jesus, Piauí, foi de 4 por mês.Termos para indexação: Trichogrammatidae, controle biológico, parasitoide, temperatura.

Effect of Different Constant Temperatures on Life History and Life Table Parameters of Trichogramma euproctidis (Hymenoptera: Trichogrammatidae)

“…Our result revealed that the optimum temperature for emergence (survival) of T. euproctidis was 32.5°C (90%), and these values are similar to other Trichogramma species as reported by Scholler and Hassan 2001 , Haile et al 2002 , El-Wakeil 2007 ( T. evanescens ), Bari et al 2015 ( Trichogramma zahiri Polaszek (Hymenoptera: Trichogrammatidae)) and Carvelho et al 2017 ( Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae)). Lessard and Boivin (2013) claimed that suboptimal temperature causes decreased energy, metabolic dysfunction, and mortality in immature stages and consequently had negative effect on the emergence rates of Trichogramma wasps.…”

Biological characteristics of Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae) under temperature stress by successive generations

“…Also in the study by Oliveira et al (2017) there was also a reduction in the values of parasitism, emergence, adult egg period and sexual ratio, when the temperature ranged from 25 °C to 33 °C. Similar tendency were also observed in other studies, regardless of the host (Carvalho et al, 2017;Milanez, Carvalho, Lima, & Pratissoli, 2018). However, despite the temperature stress condition of T. pretiosum females in this study, it was observed that the longevity, tibial length, number of parasitized eggs and adult emergence rate increased.…”

“…Among the climatic factors, the temperature is the one that exerts more influence on the parasitoids, being one of the main regulators of insects metabolism (Angilletta, Niewiarowski, & Navas, 2002). In laboratory conditions, the constant temperature of 25 °C was shown to be the most favorable for the maintenance of T. pretiosum activities, but when subjected to extremes between 28 °C and 33 °C there was a significant reduction in longevity, parasitism, emergence, developmental cycle and sexual ratio (Bueno, Parra, & Freitas Bueno, 2012;Carvalho et al, 2017;Oliveira, de Oliveira, Breda, França, & Duarte, 2017).…”

KAPASITAS POTENSI PARASITISME Trichogramma sp. (Hymenoptera: Trichogrammatidae) TERHADAP Corcyra sp.

“…Sifat parasitoid akan cenderung mengurangi aktifitas dalam memarasit inangnya pada suhu yang rendah serta akan meningkat seiring dengan meningkatnya suhu. Laju parasitasi terhadap kepadatan inang akan relatif sama, jika suhu yang ditemukan adalah sekitar 25 0 -30 0 C (Carvalho et al, 2017). Suhu yang terlalu cepat mengalami perubahan atau terlalu tinggi akan menurunkan aktifitas parasitoid, karena parasitoid akan lebih cepat kehilangan banyak cairan jika terus aktif bergerak Carvalho, et al, 2017).…”