Biologia de Geocoris punctipes (Say, 1832) (Hemiptera: Geocoridae) sobre ovos de Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) em regimes de temperatura alternantes e constantes

Abstract

The alternating and constant temperature regimes may influence the biological and growth parameters of natural enemies, so the success of biological control programs. The objective of this work was evaluate effects of alternating and constant temperature regimes (21/11°C, 30/26°C, 16.8 ºC and 28.3 °C), on the developmental time, survival, reproduction and population growth of the predator Geocoris punctipes (Say, 1832). Nymphs of G. punctipes had five instars at all temperatures evaluated. The nymphal development and the duration of the instars of G. punctipes were longer at low temperatures (16.8ºC and 21/11°C). The nymphal survival rate was lower in low temperature regimes (16.8ºC, 21/11ºC) (11.6% e 15.4%, espectively). Sex ratio of G. punctipes didn´t show significance under different temperature regimes. Females kept at higher temperatures (28.3ºC, 30/26ºC) showed pre-oviposition period shorter (3.4 and 3.1 days, respectively) compared to those exposed at lower temperatures. The oviposition period was longer for females reared at low temperatures in both alternating 21/11°C (74.8 days) and constant 16.8°C (68.3 days) compared to those on higher temperatures. The daily and total fecundity were higher in high temperatures. The parameters estimated by the fertility life table (mx, lx, rm, R0, λ, T and TD) were influenced by low temperatures, showing better results in high temperatures. The best biological and population growth performance of G. punctipes was observed at higher temperatures (30/26°C, 28.3°C), showing that species are better adapted to conditions or areas with temperatures between 26ºC and 30ºC.