Potential global distribution of Aleurocanthus woglumi considering climate change and irrigation

Citrus blackfly, Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae), is an important agricultural quarantine pest, causing substantial economic losses to citrus and many other cultivated crops. Aleurocanthus woglumi is found in tropical and subtropical regions but is presently unknown in Europe and the Mediterranean Basin. We used CLIMEX to model the potential distribution of A. woglumi under an historical climate scenario (centred on 1995), including a spatially explicit irrigation scenario. We found that A. woglumi could potentially invade the Mediterranean Basin, and south-east Asia, including Australia. There is potential for it to invade most of sub-Saharan Africa. Irrigation is revealed as an important habitat factor affecting the potential distribution of A. woglumi, increasing its potential range by 53% in Asia. Under a future climate scenario for 2050, its potential distribution increased across all continents except Africa, where potential range expansion due to relaxation of cold stresses was limited, and was offset by range decrease due to lethal heat or dry stress. As global climates warm, Europe is likely to face a substantial increase in the area at risk of establishment by A. woglumi (almost doubling under the 2050 irrigation scenario). The biosecurity threat from A. woglumi is significant in current citrus production areas and poses a challenge to biosecurity managers and risk analysts.

Aleurocanthus woglumi (citrus blackfly).

Feeding by A. woglumi damages new leaf growth, reducing nitrogen levels in infested leaves. Sooty mould growing on honeydew deposits blocks light and air from the leaves, reducing photosynthesis. This can reduce fruit set by up to 80% or more (Eberling, 1954). Crop losses of limes due to A. woglumi were recorded at 25% by Watts and Alam (1973). In Mexico, citrus blackfly is regarded as a threat to citrus crops and to other crops such as mangoes, pears or coffee grown adjacent to heavily infested citrus groves. A. woglumi is a constant menace to citrus and other crops in the USA and Venezuela. It has been recorded seriously affecting citrus in India (David and Subramaniam, 1976). Le Pelley (1968) mentions it as a severe pest of coffee in the New World.

Effect of interspecific competition among whiteflies (Homoptera: Aleyrodidae) on crops and ornamental plants in Southwestern Nigeria

Whiteflies that are pests of many crops and ornamental plants produce migratory forms during dense populations with different species sharing the same host plant. Fields surveys of these pests were conducted from 8 sampling sites within the five states (Lagos, Oyo, Osun, Ekiti and Ondo states) of Southwestern Nigeria during 2016 and 2019 to investigate the effects of interspecific competition among whiteflies on plants in the region. This survey was carried out in both wet and dry seasons. Whiteflies were collected on crops and ornamental plants in the sampling sites within the mangrove forest, rainforest and the derived savannah zones in the region. Interspecific competition was observed between four species Aleurodicus dispersus, A cocois, Aleurocanthus woglumi and Bemisia tabaci. The species population of whiteflies was analyzed using the Paleontological statistics software package (PAST) and nonparametric t-test was conducted to analyse the sharing of the host surface among species. The results obtained showed that the interspecific competition among species of whiteflies in the region is most during early rain season and yielded less whiteflies infestation and abundance at underside of plant leaves, and as well supported high number of the pest on upper leaf surfaces. The integrative analysis of the consequences of interspecific competition could provide justification for predicting species exclusion resulting into whitefly invasions of upper leaf surfaces as their new ecological niche.

Diversidade de aleirodídeos, cochonilhas (Hemiptera: Aleyrodoidea, Coccoidea) e de parasitoides (Hymenoptera) da mosca-negra-dos-citros (Aleurocanthus woglumi Ashby) (Hemiptera: Aleyrodoidea) e efeitos das etapas de beneficiamento pós-colheita em lima ácida ‘Tahiti’ (Citrus latifolia Tanaka) no Estado de São Paulo

O Brasil é o maior produtor mundial de citros, sendo também o segundo maior produtor e segundo maior exportador de lima ácida ‘Tahiti’ (Citrus latifolia Tanaka). O Estado de São Paulo é o maior exportador dessa fruta fresca. O conhecimento sobre plantas hospedeiras e a distribuição geográfica dos aleirodídeos e cochonilhas ainda é pequeno, sendo a maioria das informações disponíveis referentes a poucas espécies que provocam danos econômicos. A falta de conhecimento sobre a diversidade de hospedeiros e sua dinâmica populacional dificulta o manejo de pragas. O presente estudo teve como objetivo gerar e difundir o conhecimento sobre esses insetos, através da atualização das espécies de aleirodídeos, identificação de parasitoides, visando ao incremento das ações de manejo e sustentabilidade na cadeia da lima ácida Tahiti. Além disso, objetivou-se identificar as principais causas de perdas em pós-colheita dessa fruta. No período de junho de 2015 a junho de 2017, foram coletadas quinzenalmente, em dois pomares de limão ‘Tahiti’, 240 folhas infestadas por aleirodídeos e cochonilhas. As folhas infestadas foram imediatamente transportadas ao laboratório e os insetos avaliados e identificados. As pupas dos parasitoides recuperados foram acondicionadas em microtubos plásticos de 2mL e mantidas em sala climatizada por até 30 dias para emergência dos adultos. Das 51 coletas realizadas nas duas áreas de lima ácida Tahiti obteve-se um total de 256.976 insetos. Foram recuperadas quatro espécies de aleirodídeos e 21 espécies de cochonilhas.