Abstract
Simple SummaryThis study evaluated the potential of Trichogramma euproctidis to parasitize Helicoverpa armigera eggs of different ages in laboratory arenas. H. armigera is a major pest of agricultural crops in Iran and other countries. T. euproctidis is an important egg parasitoid of lepidopteran eggs and could be used in augmentative biological control of H. armigera. The objective of this research was to determine if young rather than old H. armigera eggs were optimal for T. euproctidis development, reproduction, and life table parameters. Results indicated that T. euproctidis developed faster and produced more offspring in 14 h old rather than 38 h or 62 h old H. armigera eggs. A life table analysis confirmed these results. This study is important because it documents for the first time that T. euproctidis can utilize H. armigera as a rearing host. Using young rather than old host eggs could ensure the persistence of a T. euproctidis mass production system to support augmentative releases.The noctuid Helicoverpa armigera is an economically important pest of agricultural crops in Iran and other countries. Research is evaluating the capacity of Trichogramma parasitoids to control H. armigera populations on field crops. The objective of this research was to determine if young rather than old H. armigera eggs were optimal for Trichogramma euproctidis development, reproduction, and life table parameters. Bioassays involved exposing T. euproctidis mated females to H. armigera 14, 38, or 62 h old eggs within 24 h in laboratory arenas. Results indicated that the number of host eggs parasitized successfully by T. euproctidis decreased as host egg age increased. Host egg age had no significant effect on T. euproctidis adult emergence. Adults that developed in 14 h old eggs had greater longevity and fecundity than those that developed in 38 h or 62 h old eggs. The intrinsic rate of increase (r) was greatest, and the mean generation time (T) was lowest for T. euproctidis reared in 14 h old eggs. This study indicates that young H. armigera eggs are more suitable than old ones for T. euproctidis development and reproduction. This study is important because it provides evidence, for the first time, that T. euproctidis can utilize H. armigera as a rearing host. Using young rather than old host eggs could ensure the persistence of a T. euproctidis mass production system to support augmentative releases.
Highlights
Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is an important pest of agricultural crops around the world
The specific objective of this research is to determine if young rather than old H. armigera eggs are optimal for T. euproctidis development, reproduction, and life table parameters
Host age had a significant effect on the mean number of eggs parasitized by T. euproctidis (F = 32.43; df = 2, 27; p < 0.0001) (Table 1)
Summary
Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is an important pest of agricultural crops around the world. If uncontrolled, it can significantly reduce production and yield of cotton (Gossypium hirsutum L.) in northeast Iran and tomato (Lycopersicon esculentum Mill.) in southwest Iran [1,2,3,4,5]. Using biological control as an alternative to conventional insecticides to manage H. armigera should be encouraged [12]. The development of techniques to conserve and utilize indigenous natural enemies, predators and parasitoids that attack egg and larval stages, could be critical to successful biological control of H. armigera [12]. Mass rearing and releasing the most important natural enemies could boost the chances of controlling H. armigera
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