ABSTRACT
The tomato fruitworm Helicoverpa armigera (Hübner) is regarded as a serious pest that affects a great number of field crops globally. One of the environmentally safe alternatives to the utilization of insecticides is controlling H. armigera via the release of biological control agents by employing parasitoids, e.g., trichogrammatid species. One of the desired parasitoids indigenous to southwestern Iran is Trichogramma euproctidis (Girault). To anticipate the outcomes of augmentative releases of T. euproctidis in the field, the numerical and functional responses of female T. euproctidis that parasitizes the eggs of H. armigera were determined in the laboratory. The densities of host eggs per glass tube arena (length: 10 cm, diameter: 1 cm) were 2, 4, 8, 16, 32, 64, or 128 individuals. The functional response to the eggs of H. armigera indicated Holling's type II response. The estimated handling time and attack rate from the random parasitoid equation were 0.6898 h and 0.00823 h, respectively. This indicates that, at the maximum level, each T. euproctidis was capable of parasitizing 34.79 eggs a day. At the 128 host egg density, the number of eggs laid, that is, the numerical response, ascended as the density of host eggs increased up to a maximum of 89.90 eggs per female. According to the obtained results of the present investigation, T. euproctidis can serve as an appropriate candidate for augmentative biological control of H. armigera. Nevertheless, it is necessary to conduct complementary experiments in greenhouses and open fields.
Subject(s)
Hymenoptera , Insecticides , Lepidoptera , Moths , Wasps , Female , Animals , Hymenoptera/physiology , Biological Control Agents , Crops, Agricultural , Ovum , Wasps/physiologyABSTRACT
Imunit is a mixture of alpha-cypermethrin + teflubenzuron, and has been launched for controlling caterpillars. In this study, the effects of Imunit at LC50 and LC30 were investigated on parental and offspring generation of S. cilium, according to age-stage, two-sex life table. The experiments were conducted by leaf dipping method at 25 °C and 60 ± 5% relative humidity, under a cycle of 16 h fluorescent light and 8 h darkness. LC30 and LC50 concentrations of Imunit increased the immature developmental time of S. cilium in the offspring generation, while the LC50 of Imunit significantly reduced the developmental time of adults. The adult pre-oviposition period and total pre-oviposition period considerably increased when offspring were treated with LC50 of Imunit. In offspring of S. cilium exposed to LC50 and LC30 concentrations of Imunit, the gross reproductive rate (GRR), net reproduction rate (R0), the intrinsic rate of population increase (r), and the finite rate of population increase (λ) significantly reduced compared to the control. This study showed that the application of Imunit at LC50 could suppress the S. cilium population and can be used in the integrated management program of this pest.
ABSTRACT
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.
ABSTRACT
A new Anagnorisma species, Anagnorisma chamrani sp. n., is described from Binaloud Mountains of Khorasan-e-Razavi province in north-eastern Iran, and compared with its sister species, Anagnorisma eucratides (Boursin, 1960). The adults, and male and female genitalia of both species are illustrated in 11 figures. The genus Anagnorisma is recorded for the first time for the fauna of Iran.