Levantamentos de campo foram realizados durante quatro safras de soja na região Sul do Brasil, visando avaliar as espécies de parasitóides que ocorrem em ovos de Anticarsia gemmatalis Hübner, 1818 e a incidência de parasitismo ao longo do ciclo da cultura. Os ovos foram coletados visualmente em folhas de soja e com a colocação de gaiolas em campo contendo adultos de A. gemmatalis para que realizassem oviposições. A espécie Trichogramma acacioi Brun, Moraes & Soares, 1984 foi registrada pela primeira vez parasitando ovos de A. gemmatalis e T. lasallei Pinto, 1998 teve seu primeiro registro no Brasil através destes levantamentos. Foram também encontradas as espécies T. pretiosum Riley, 1879, T. rojasi Nagaraja & Nagarkatti, 1973 e T. atopovirilia Oatman & Platner, 1983, já registradas anteriormente neste hospedeiro. Ovos parasitados foram coletados durante todo o período de ocorrência de A. gemmatalis, de janeiro a março de cada ano. Os índices de parasitismo foram de 4,8% em 2000 e 2002, 23,3% em 2001 e 28,9% na safra 2003. T. pretiosum e T. acacioi foram responsáveis por mais de 80% do parasitismo nos ovos coletados a cada ano, enquanto T. atopovirilia, T. rojasi e T. lasallei, apresentaram menos de 20% de incidência. Não houve diferença significativa entre a razão sexual e o número de parasitóides emergidos por ovo hospedeiro entre as espécies de Trichogramma coletadas. A coleta de ovos naturalmente depositados foi menos eficiente em comparação à coleta de ovos depositados por fêmeas no interior das gaiolas, o qual mostrou-se um método satisfatório para a estimativa qualitativa de parasitismo em ovos de A. gemmatalis.

Field surveys were carried during four soybean seasons in Southern Brazil to evaluate the occurrence of parasitoids in eggs of Anticarsia gemmatalis Hübner, 1818 and their incidence along the crop season. Eggs were collected by visual search on soybean leaves and from plants kept inside cages where A. gemmatalis moths were allowed to lay eggs. Trichogramma acacioi Brun, Moraes & Soares, 1984 was recorded for the first time in eggs of A. gemmatalis and the citations in the literature of Trichogramma lasallei Pinto, 1998 in Brazil where based on the material collected in this survey. Apart from these species, Trichogramma pretiosum Riley, 1879, Trichogramma rojasi Nagaraja & Nagarkatti, 1973 and Trichogramma atopovirilia Oatman & Platner, 1983 were also collected, all of which have been previously recorded in this host. Parasitized eggs were collected all over the period of occurrence of A. gemmatalis, from January to April each year. Total parasitism ranged from 4.8% in 2000 and 2002, 23.3% in 2001 and 28.9% in 2003. T. pretiosum and T. acacioi accounted for more than 80% of the parasitoids emerged each year, followed by T. atopovirilia, T. rojasi and T. lasallei, with less than 20% of incidence. Both the sex ratio and the mean number of parasitoids/egg did not differ among the species. Searching for A. gemmatalis eggs proved to be time consuming in comparison to the collection of eggs laid by moths inside the cages, which showed to be a useful method to provide qualitative estimates of parasitism in eggs of A. gemmatalis.

Trichogramma atopovirilia Oatman & Platner is an egg parasitoid of the corn earworm Helicoverpa zea (Boddie) (Lepidoptera, Noctuidae), and has recently been collected from eggs of Anticarsia gemmatalis Hübner on soybeans. In order to evaluate the suitability of A. gemmatalis eggs as hosts of T. atopovirilia, field surveys were conducted in 1999 and 2000 on corn and soybeans, and a colony of the parasitoid was established in laboratory. At 25 ºC, development from oviposition to emergence lasted nine days and a sex-ratio of 0.58 (females:males) was obtained. Females lived significantly longer (11.4 days) when kept in ovipositional activity, than in the absence of host eggs (6.6 days). Total fecundity averaged 104.5 parasitized eggs, resulting in the emergence of 138.3 descendents. Mean daily fecundity was highest (30 eggs/female) on the first day. Oviposition continued until one day before the death of the females, however 70% of the eggs were laid during the first four days after emergence. A female-biased progeny was produced during the first three days of oviposition, whereas further ovipositions were male-biased. Females lived significantly longer when exposed to host eggs in comparison to females deprived of eggs. The results show that eggs of A. gemmatalis are suitable for the development of T. atopovirilia, and this parasitoid should be considered in future programs of biological control of the velvetbean caterpillar.