Mean daily progeny production by Trichogramma minutum (“Maine strain”) was 15.2 in Choristoneura fumiferana and 10.9 in Sitotroga cerealella eggs. Total progeny production was higher in S. cerealella, but not significantly different from that of C. fumiferana eggs. Significantly more eggs were deposited by T. minutum the first day than in subsequent days regardless of host. We found no significant relationship between progeny produced by females and the day of male death as previously reported. Ratio of females:males decreased significantly with increasing age and opposition activity of the mother. The oviposition period spanned 68% of the female's life span when S. cerealella eggs were available; whereas females spent significantly less time (60%) ovipositing in C. fumiferana eggs.

Spruce budworm egg deposition spanned 27 days during both 1979 and 1980. The egg deposition curve is essentially a normal bell-shaped distribution with a slight skew to the right. Spruce budworm eggs are most acceptable to T. minutum Riley for successful parasitism during the earlier stages of host–egg development. Parasitism rates at two different temperatures (21 °C and 27 °C) were significantly greater for 1- to 3-day-old eggs than for 6- to 8-day-old spruce budworm eggs. Major reduction in host–egg acceptability occurred after the fifth day at 21 °C and after the 4th day at 27 °C.

Three body dimensions (body length, head width, and abdomen width) were used to determine size differences between laboratory-reared and wild populations of Trichogramma minutum Riley. Six separate groups of T. minutum were measured: three groups were from Sitotroga cerealella (Olivier) eggs, two from spruce budworm Choristoneura fumiferana (Clemens) eggs, and one from wild populations of spruce budworm.Female T. minutum from spruce budworm (large host) eggs were significantly larger for all body dimensions than T. minutum from S. cerealella (small host) eggs. Male T. minutum from field-collected spruce budworm eggs were significantly larger for all body dimensions than T. minutum reared for more than one generation in S. cerealella eggs.A significant reduction in female parasitoid size was observed during the initial generations of T. minutum reared in the smaller host (S. cerealella). However, this size reduction was not permanent. Following numerous generations in the S. cerealella host eggs, a significant increase in female parasitoid size was noted within the first generation of T. minutum reared in the spruce budworm host eggs.

Can. En?. 117: 556563 (1985) Development rates of the parasitoid, Trichogramma minutum Riley, were studied to provide information required in timing field releases of T. minutum for suppression of egg populations of the spruce budworm, Choristoneura fumiferana (Clemens). Development was observed in eggs of 2 host species, C. fumiferana and Sitotroga cerealella (Olivier), at constant temperatures of 14,21, and 27°C. Parasitoid development varied directly with temperature. Parasitoids developed more rapidly in eggs of S. cerealella than in those of C. fumiferam. Parasitoid males developed faster than females in some host-temperature treatments. Development of T. minutum is apparently rapid enough to allow progeny of parasitoids released early in the spruce budworm's oviposition period to mature and be available to oviposit in budworm eggs deposited later in the budworm oviposition period. Potential release strategies are discussed.On a ttudit les taux de dtveloppement du parasitoide Trichogramma minutum Riley afin d'obtenir l'information reauise Dour le relkhement au bon moment de T. minutum . . en vue de la suppression des populations d'oeufs de la tordeuse des bourgeons de l'tpinette, Choristoneurafumiferana (Clemens). On a suivi le dtveloppement dans des oeufs de 2 es@ces d'hBtes, C. fumiferana et Sitotroga cerealella (Oliver), aux tempkratures constantes de 14,21 et 27OC. Le dtveloppement du parasitoide a varit directement en fonction de la tempkrature. Les parasitoides se sont dtveloppks plus rapidement dans les oeufs de S. cerealella que dans ceux de C.fumiferana. Les parasitoides miles se sont dtveloppks plus rapidement que les femelles II certaines tempkratures.Le dtveloppement de T. minutum est apparamment suffisamment rapide pour permettre aux progtnitures de parasitoides relkhts tat au cours de la pkriode de ponte de la tordeuse de maturer pour pondre dans les oeufs de tordeuse dtposts plus tard au cours de sa pkriode de ponte. On discute de strattgies possibles de rellhement.