Field performance of the parasitoid wasp, Trichogrammatoidea armigera (Hymenoptera: Trichogrammatidae) following releases against the millet head miner, Heliocheilus albipunctella (Lepidoptera: Noctuidae) in the Sahel

The effectiveness of the egg parasitoid Trichogrammatoidea armigera Nagaraja (Hymenoptera: Trichogrammatidae) in controlling Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae), a major insect pest of pearl millet in the Sahel was assessed during two consecutive years in Niger on-station and on-farm conditions. We found that released T. armigera were able to find and parasitize host eggs within pearl millet fields both onstation and in farmers’ fields. On-station releases of T. armigera led to an average 4.86-fold increase in T. armigera parasitism compared to control fields, where no parasitoids were released. Likewise, on-farm releases of T. armigera led to up to 5.31-fold more egg parasitism by T. armigera in release fields than in control. Our results suggest the effectiveness of T. armigera and lays the groundwork for using T.armigera in augmentative biological control of H. albipunctella in the Sahel

Parasitism of Locally Recruited Egg Parasitoids of the Fall Armyworm in Africa

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is an insect native to the tropical and subtropical Americas that has recently spread to Africa, where it predominately attacks maize, sorghum and other plant species. Biological control is an environmentally friendly way of combatting the pest and contributes to an integrated pest management approach. In Africa, several trichogrammatid parasitoids and Telenomus remus Nixon (Hymenoptera: Platygastridae) have been found parasitizing eggs of the FAW. In Niger, the egg parasitoids encountered include Trichogrammatoidea sp. (Hymenoptera: Trichogrammatidae) and Telenomus remus Nixon. Parasitism of the FAW eggs by the two egg parasitoids was assessed in the laboratory, followed by field testing on sentinel eggs. In the laboratory, T. remus parasitized on average 78% of FAWeggs, compared to 25% for Trichogrammatoidea sp. Telenomus remus was able to parasitize egg masses that were fully covered with scales, while Trichogrammatoidea sp. parasitized only uncovered egg masses. On-farm releases of T. remus in sorghum fields caused up to 64% of FAW egg parasitism. Parasitized eggs yielded viable progeny, which can contribute to FAW egg parasitism build-up during the cropping season. Our findings lay the groundwork for the use of T. remus in augmentative releases against FAW in Africa

Development of an Optimum Diet for Mass Rearing of the Rice Moth, Corcyra cephalonica (Lepidoptera: Pyralidae), and Production of the Parasitoid, Habrobracon hebetor (Hymenoptera: Braconidae), for the Control of Pearl Millet Head Miner

The rice moth, Corcyra cephalonica Stainton, an alternate host for the production of the parasitoid, Habrobracon hebetor Say, was reared on different diets, including pearl millet [Pennisetum glaucum (L.) R. Br.] (Poales: Poaceae) flour only, and in combinations of flours of sorghum [Sorghum bicolor (L.) Moench] (Poales: Poaceae), peanut (Arachis hypogea L.) (Fabales: Fabaceae), and cowpea [Vigna unguiculata (L.) Walp.] (Fabales: Fabaceae) to identify the optimal and economical proportion to be used under the conditions of Niger. The addition of cowpea or peanut to the pearl millet diet slightly increased C. cephalonica larval development time. Likewise, the addition of cowpea or peanut to cereal diets yielded a higher C. cephalonica larval survival. Female moths emerging from larvae fed on cereal and legume mixed diets produced higher eggs compared to the ones fed on sole and mixed cereals. Among legumes, cowpea addition is most interesting in terms of cost/production of C. cephalonica larvae. However, female moths emerging from larvae fed on different millet cowpea mix (5, 25, and 50%) laid significantly more eggs than those fed on sole pearl millet. Further, individual C. cephalonica larvae fed on 75% pearl millet + 25% cowpea produced significantly more H. hebetor. With an initial 25 C. cephalonica larvae kept for a 3-mo rearing period, the number of H. hebetor parasitoids produced will reach 2.68–10.07 million. In terms of cost/production ratio, the 75% pearl millet: 25% cowpea yielded better results

Timing of releases of the parasitoid Habrobracon hebetor and numbers needed in augmentative biological control against the millet head miner Heliocheilus albipunctella

Heliocheilus albipunctella de Joannis (Lepidoptera: Noctuidae) is one of the major insect pests of pearl millet in the Sahel. The native parasitoid, Habrobracon hebetor Say (Hymenoptera: Braconidae), is currently being promoted for augmentative biological control of the pest in the Sahel. The current study was carried out to identify the right time for releases of the parasitoid using either pearl millet growing stage, or pest occurrence as reference, and to determine the optimal number of parasitoids needed to cover a given area. Our results indicate that release of parasitoids at the panicle emergence stage or six weeks after first sight of eggs of H. albipunctella lead to highest parasitism of H. albipunctella larvae by H. hebetor. The dose of 800 parasitoids for a distance of 3 km radius was enough for controlling H. albipunctella. The implications of the results are discussed toward cost effective and practical recommendation adapted to the Sahelian conditions

Native parasitoids recruited by the invaded fall army worm in Niger

Surveys of fall army worm Spodoptera frugiperda (J. S. Smith) on maize and sorghum in Niger revealed the occurrence of egg parasitoids (Trichogrammatoidea sp., Trichogramma sp., and Telenomus sp.), egg-larval parasitoids (Chelonus sp.), and larval parasitoids (Cotesia sp., and Charops sp.)

The parasitoid Trichogrammatoidea armigera Nagaraja (Hymenoptera: Trichogrammatidae) is a potential candidate for biological control of the millet head miner Heliocheilus albipunctella (de Joannis) (Lepidoptera: Noctuidae) in the Sahel

Pearl millet, Pennisetum glaucum (L.) R. Br., is a crop grown throughout West Africa, especially in the Sahel. Pearl millet is the major staple food for the population of the Sahel, particularly for household use. It is one of the world’s most resilient drought-tolerant cereal crops, surviving even in the poorest soils in the driest regions and in the hottest climates. Despite this extreme climatic adaptation, pearl millet suffers from many biotic constraints, including insect pests (Nwanze and Harris, 1992). Among these, the stem borer (MSB) Coniesta ignefusalis (Hampson) (Lepidoptera: Crambidae) and the millet head miner (MHM) Heliocheilus albipunctella (de Joannis) (Lepidoptera: Noctuidae) are the major chronic insect pests of millet in the Sahel, including Niger. The MSB develops on many species of the Poaceae family; in the Sahel, it develops 2–3 generations per year on pearl millet during the rainy season and diapauses in leftover pearl millet stems during the rest of the year (Youm et al., 1996). The damage from C. ignefusalis is due to the feeding of developing larvae in millet stalks; first generation larvae cause dead hearts and stand loss, while the second and third generations cause lodging, disruption of the vascular system, and inhibition of grain formation (Harris, 1962; Youm et al., 1996). The MHM is a univoltine and monophagous species, which develops on millet in the Sahel during the rainy season between July and October and spends the remainder of the season in diapause in the soil (Gahukar et al., 1986). Infestations of H. albipunctella are more severe in the drier zones of the Sahel (Nwanze and Harris, 1992). The damage from H. albipunctella is due to larvae that feed on the panicle and prevent grain formation (Nwanze and Harris, 1992). Almost every year, outbreaks of the MHM are observed in the Sahel, especially on millet planted early or earlymaturing cultivars, while millet planted later or late-maturing cultivars is more affected by MSB (Gahukar et al., 1986; Youm et al., 1996). Both insect pests inflict significant yield losses ranging from 15% to total crop failure for C. ignefusalis (Harris, 1962; Ajayi, 1990) and from 40% to 85% for H. albipunctella (Gahukar et al., 1986; Krall et al., 1995)..

Heart and en-bloc thymus transplantation in miniature swine

BackgroundDonor-specific tolerance to organ allografts might be induced by cotransplantation of a sufficient amount of vascularized donor thymus. To facilitate donor thymus-induced cardiac allograft tolerance, we have developed a novel technique for heart and en-bloc thymus transplantation in swine.MethodsDonor heart and en-bloc thymus grafts were prepared by a technique that preserves the entire arterial supply and venous drainage of the right thymic lobe. En-bloc grafts (n = 4) were transplanted heterotopically into the abdomens of major histocompatibility complex-matched miniature swine. Recipients received 12 days of cyclosporine intravenously. Grafts were monitored by palpation, electrocardiographic monitoring, and periodic open biopsy. Engraftment of the donor thymus was demonstrated by measuring the proportion of recipient-type thymocytes in the donor thymus with flow cytometry.ResultsAll of the heart and en-bloc thymus grafts had normal cardiac contractility and immediate perfusion of the thymus. All en-bloc grafts were accepted for more than 200 days without significant acute cellular rejection or cardiac allograft vasculopathy. Thymic tissue of en-bloc grafts displayed normal architecture and supported thymopoiesis of recipient-type cells.ConclusionWe have validated a new technique of donor thymus transplantation that could have utility in human heart transplantation

Economic feasibility of an augmentative biological control industry in Niger

Farmers in Niger are vulnerable to high millet yield losses due to the millet head miner, Heliocheilus albipunctella De Joannis (Lepidoptera: Noctuidae), for which pest control options are limited. Researchers have developed a procedure to multiply and spread an augmentative biological control agent Habrobracon hebetor Say (Hymenoptera: Braconidae) which is effective in limiting millet yield losses due to the pest. This study assesses the economic viability of small businesses to produce and sell biological control agents. It analyzes the profitability of the businesses under alternative pricing regimes given estimated costs to produce and distribute biological control agents. The economic assessment provides budget analysis for potential businesses and discusses options for scaling, price setting, and organizing. Our study suggests that the small H. hebetor industry should turn a profit in Niger at relatively low prices for the biological control agents of $3.00-$4.00 per bag with 15 bags needed per village. Competitive wages are achievable for the businesses that sell to at least 13 villages. Each business would hire three workers from late May to late August. Commercialization of H. hebetor would generate opportunities for wide geographic distribution of the technology on a sustainable basis in Niger

Host stage preference and parasitism behaviour of Aenasius bambawaleian an encyrtid parasitoid of Phenacoccus solenopsis

In Pakistan, the cotton mealybug, Phenacoccus solenopsis Tinsley (Sternorrhyncha (Homoptera): Pseudococcidae), is a serious pest of many cultivated plants. A parasitoid, Aenasius bambawalei Hayat (Hymenoptera: Encyrtidae), is associated with P. solenopsis. In order to mass rear A. bambawalei for a biological control program, it is important to investigate the parasitoid’s host stage preference and its parasitism behavior for P. solenopsis in order to optimize production. The present tudy showed that under both choice and no choice conditions, the parasitoid preferred 3rd instar and pre-reproductive host stage mealybugs for parasitism. Parasitoid larva developing inside the host exhibited a greater longevity, shorter developmental period and longer body size in these preferred host stages. Our study also confirmed that A. bambawalei showed no attraction to male mealybugs and no host feeding on any host stage was recorded. The ability of the parasitoid to effectively discriminate between suitable and non-suitable stages means that it is feasible to rear it on a mixed population