Sweetpotato Whitefly Bemisia Tabaci Gennadius Research Articles

Transgenerational effect of insecticides on juvenile development time of the Sweetpotato whitefly parasitoid Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae)

Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) is a highly efficient parasitoid that has been commercially used for augmentative biological control of the sweetpotato whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae). The success of control efforts with this parasitoid could be compromised by the use of non-selective pesticides. This study was conducted to determine if acetamiprid, imidacloprid, thiamethoxam, spinetoram, and sulfoxaflor had transgenerational effects on juvenile development of E. mundus. The mean development time from oviposition (OVP) to first sign of parasitism (FSP) for progeny of females treated with control was 9.03 days, which was the shortest compared to the insecticide treatments. After FSP, the control groups reached their pre-pupal (PP) stage in an average time of 3.85 days, while it was in the range of 3.98–4.46 days for insecticide-treated groups. The developmental period from pre-pupal to black-eyed pupal stage ranged from 2.32–2.69 days for parasitoids treated with insecticides, but it was 2.22 days for the control group. The overall mean development time—from oviposition until adult emergence—was 16.24 days for control, which was statistically shorter than all other treatments. Spinerotam and sulfoxaflor prolonged immature development by 2.37 and 1.83 days, respectively, when compared with the control. Male development was slightly shorter than that of female in control, spinetoram, and sulfoxaflor groups, and the opposite was true for the neonicotinoids. Compared to the neonicotinoids, the non-neonicotinoids had more negative effect on juvenile development of E. mundus.

Lethal and Sublethal Effects of Flupyradifurone on Bemisia tabaci MED (Hemiptera: Aleyrodidae) Feeding Behavior and TYLCV Transmission in Tomato.

Pesticides primarily affect target organisms via direct toxicity, but may also alter the feeding behaviors of surviving individuals in ways that alter their effect on host plants. The latter impact is especially important when pests can transmit plant pathogens. The Mediterranean (MED) population of the sweetpotato whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) transmits Tomato yellow leaf curl virus (TYLCV), a pathogen that can be economically devastating in field and greenhouse cropping systems. We first assessed the impact of sublethal (LC15) and label concentrations of flupyradifurone, a butenolide-derived insecticide, on the feeding behavior of TYLCV-infected MED on tomato. We next measured the effect of flupyradifurone on plant TYLCV load, vector transmission efficiency, and MED survival. Both the LC15 and label flupyradifurone concentrations dramatically altered MED feeding and caused the near cessation of both salivation and phloem ingestion (necessary for viral transmission and acquisition, respectively). Both concentrations also significantly reduced plant TYLCV load, and the label rate of flupyradifurone sharply decreased TYLCV transmission while killing >99% of MED. As the first report of pesticide-induced changes in the feeding behavior of viruliferous Bemisia, our findings highlight the potential importance of chemically driven feeding cessation in the control of TYLCV and other Bemisia-transmitted plant pathogens.

Sensitivity ofBemisia tabaci(Hemiptera: Aleyrodidae) and the Generalist PredatorOrius albidipennis(Hemiptera: Anthocoridae) to Vapors of Essential Oils

Abstract In recent years, plant derivatives such as essential oils have been one of the most promising sources for the substitution of chemical insecticides for pest management. A laboratory assessment was conducted to find the fumigant toxicity of Artemisia sieberi Besser, Pelargonium roseum Andrews, and Ferula gummosa Boiss essential oils against the sweetpotato whitefly Bemisia tabaci Gennadius and its predator, Orius albidipennis Reuter. The responses varied depending on oil type and insect species. Based on 24-h median lethal concentration (LC50) values, all the essential oils showed similar toxicity to B. tabaci. Ferula gummosa essential oil had lesser toxicity (LC50, 3.46 μll−1 air) than P. roseum (LC50, 0.95 μll−1 air) and A. sieberi (LC50, 0.62 μll−1 air) against O. albidipennis. The toxicity of the oils increased for both insects by increasing the exposure time from 3 h to 48 h. A comparison of the essential oils' toxicity on the two insects showed a lower susceptibility of O. albidipennis to t...

Predation by Nesidiocoris tenuis on Bemisia tabaci and injury to tomato

Tomato is the most important vegetable crop in Spain. The mirid bug Nesidiocoris tenuis (Reuter) commonly appears in large numbers in protected and open-air tomato crops where little or no broad-spectrum insecticides are used. Nesidiocoris tenuis is known to be a predator of whiteflies, thrips and several other pest species. However, it is also considered a pest because it can feed on tomato plants, causing necrotic rings on stems and flowers and punctures in fruits. Our objectives were to evaluate predation by N. tenuis on sweetpotato whitefly Bemisia tabaci Gennadius under greenhouse conditions and establish its relationship to N. tenuis feeding on tomato. Two different release rates of N. tenuis were compared with an untreated control (0, 1 and 4 N. tenuis plant−1) in cages of 8 m2. Significant reductions of greater than 90% of the whitefly population and correspondingly high numbers of N. tenuis were observed with both release rates. Regression analysis showed that necrotic rings on foliage caused by N. tenuis were best explained by the ratio of B. tabaci nymphs:N. tenuis as predicted by the equation y = 15.086x − 0.6359.

Persistence of soil and foliar azadirachtin treatments to control sweetpotato whitefly Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) on tomatoes under controlled (laboratory) and field (netted greenhouse) conditions in the humid tropics

Persistence of neem-based products against sweetpotato whitefly Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) was tested in air conditioned rearing rooms and tropical netted greenhouses (GHs). Two commercial neem products, NeemAzal®-T/S (1% azadirachtin) and NeemAzal®-U (17% azadirachtin), were used. Foliar application, under room conditions at dose-rates of 7 and 10 ml NeemAzal®-T/S, induced an immature mortality of 32 and 44%, respectively, whereas 7 days post-application, under GH conditions, mortality rates declined to 5 and 7%, respectively. This result indicated rapid dissipation of the active ingredients. However, systemic application by soil drenching resulted in more stable effects under both laboratory and GH conditions. After soil drenching with solutions of 3.0 g NeemAzal®-U until 7-day, immature mortality declined from 88% for the first day to almost half (45%) by day-7 in the GH, and from 90% on first day to 64% by day-7 under laboratory condition. Similar response trends for B. tabaci were obtained for other parameters such as adult colonisation, egg deposition, and egg hatch. The loss of efficiency of the neem products was clearly related to dose-rate, methods of application, and environment (temperature and UV). Soil application is therefore, a convenient approach to achieve high efficiency and persistence with neem products under the conditions in tropical GH environments for whitefly management.