Effects of diet, temperature and photoperiod on development and survival of the bigeyed bug, Geocoris lubra

Bigeyed bugs (Geocoris spp., Hemiptera: Geocoridae) are common predators in Australian agricultural crops yet the development and reproductive biology of Australian geocorids has not been described before. Here we present the effects of diet, temperature and photoperiod on the development and survival of Geocoris lubra Kirkaldy from egg to adult. Nymphal survival of G. lubra reared on live aphids (Aphis gossypii Glover) was very low but improved slightly on a diet of Helicoverpa armigera (Hubner) eggs. Development was faster and nymphal survival improved significantly at 27 degrees C compared with 25 degrees C. Further investigation at 27 degrees C showed photoperiod influenced development time, but not survival of immature G. lubra. Development time was significantly longer at 10L:14D. Fecundity of first generation G. lubra was not affected by photoperiod, although egg viability was greater at 12L:12D

Parasitismo natural em ovos crisopídeos Natural egg parasitism of chrysopids

Os predadores, em geral, apresentam hábitos generalistas e por isso podem ser usados em programas de controle biológico, em diferentes agroecossistemas. A sobrevivência dos predadores é afetada por diversos fatores, como, por exemplo, a presença de parasitóides. Este trabalho foi conduzido com os objetivos de identificar os parasitóides de crisopídeos, especialmente os parasitóides de ovos, e determinar o nível de parasitismo natural. As amostragens foram feitas na Embrapa Hortaliças, em campos de milho-doce, de setembro/1997 a fevereiro/1998. Os ovos de crisopídeos foram coletados semanalmente, sendo individualizados em cápsulas de gelatina até a emergência da larva e/ou do parasitóide. Foram coletados 800 ovos de crisopídeos, sendo que em 71% dos ovos, as larvas sobreviveram; 9% dos ovos foram considerados inviáveis e 20% foram parasitados por seis espécies de microhimenópteros. Destes, 57% foram parasitados por Telenomus sp. (Scelionidae), 32% por Trichogramma pretiosum (Trichogrammatidae), 6% por Oencyrtus chrysopae Crawford (Encyrtidae) e 5% por Aprostocetus sp. (Eulophidae).<br>Most predators, in general, have generalist habits and can be used as biological control agents in several crops. Predator survival is affected by several factors, such as occurrence of parasitoids. The main purpose of this research was to identify the parasitoids of chrysopids, especially egg parasitoids and their level of parasitism. The samples were taken in a sweet-corn field at Embrapa Hortaliças from September/1997 to February/1998. The chrysopids eggs were collected weekly and then individualized in gelatine capsules until larval or parasitoid emergency. A total of 800 eggs were collected. The predator emerged from 71% of the eggs, 9% were inviable eggs and the other 20% were parasitized by six species of microhymenopterans. Among these, 57% were parasitized by Telenomus sp. (Scelionidae), 32% were parasitized by Trichogramma pretiosum (Trichogrammatidae), 6% by Oencyrtus chrysopae Crawford (Encyrtidae) and 5% by Aprostocetus sp. (Eulophidae)