Tetrastichus howardi (Olliff) (Hymenoptera: Eulophidae), a pupal parasitoid of a great number of Lepidoptera pests, has a great potential for biological control. To investigate the olfactory system of this parasitoid, we examined the morphology and ultrastructure of the antennal sensilla of both male and female T. howardi using scanning and transmission electron microscopic techniques. Antennae of male and female T. howardi were geniculate in shape, which consisted of scape, pedicel and flagellum with 5 and 4 flagellomeres, respectively. The sexual differences were recorded in the types, structure, distribution and abundance of antennal sensilla of T. howardi. Fourteen morphologically distinct types of antennal sensilla were found on the female antennae, while seventeen on the male antennae. They were: multiporous plate sensilla (MPS1-4), chaetica sensilla (CH1-3), multiporous trichodea sensilla (MTS), aporous trichodea sensilla (ATS1-5), multiporous grooved peg sensilla (MGPS), coeloconic sensilla (COS), campaniform sensilla (CAS), terminal finger-like hairy sensilla (TFI), cuticular pore (CP), and ventral sensory plaque (VSP). MPS4, ATS (3-5), and VSP only occurred on the male antennae, while MPS2 and MPS3 only on the female antennae. The MPSs, MTS, MGPS, TFI, and CP may function as olfactory sensilla involving in detecting odor stimuli whereas the ATSs, CHs, and CAS may serve as mechanoreceptors. COS were presumed to play a role as chemo-, thermo- or hygro-receptor. The results could facilitate future studies on the biology of olfaction in T. howardi.

The fall armyworm, Spodoptera frugiperda, is a lepidopteran pest that feeds on many economically important cereal crops such as corn, rice, sorghum, and sugarcane. Native to the Americas, it has become a serious invasive pest in Africa and Asia. Recently, this pest was found in China and has spread quickly across the country. As S. frugiperda will most likely become a major pest in China, Integrated Pest Management strategies, including biological control methods, should be developed to manage its populations. Here, we report the detection of Telenomus remus parasitizing S. frugiperda eggs in cornfields in southern China based on morphological and molecular evidence. Our preliminary surveys indicated that the parasitism rates of T. remus on S. frugiperda could reach 30% and 50% for egg masses and per egg mass, respectively. Further application of T. remus against S. frugiperda in biological control programs are discussed.

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BACKGROUND: Fruit flies are important economic pests of fruits, vegetables, and nuts all over the world. In this study, a permanent ecological trap, which was created by the ovicidal effect of phytogenic hydrogen cyanide (HCN) liberated from passion fruits due to oviposition by fruit flies and can be used in the pest management, were determined. RESULTS: Observation of fruit fly eggs in Passiflora within the passion fruit cultivation region in southern China, from Aug 2019 to Oct 2020 showed that the exotic Passiflora attracted the native fruit flies to oviposit, but the eggs could not hatch. Using classical staging to categorize embryonic development and fumigation assays, we show that oviposition by fruit fly on passion fruits, release HCN from the cyanogenic mesocarp. Exposure of the eggs to HCN causes arrest of embryonic development and finally the death of eggs. CONCLUSION: Our results reveal that the life cycle of fruit fly in Passiflora is interrupted at the egg stage. Consequently, we predict that this ecological trap may be permanent. Extensive cultivation of the Passiflora vine as a dead-end trap crop may be an effective avenue to reduce populations of fruit fly pests.