Infestation of Aphis gossypii Glover (Hemiptera: Aphididae) on soybeans in São Paulo state, Brazil

ABSTRACT Aphis gossypii Glover (Hemiptera: Aphididae), also known as the cotton aphid, is a notable pest of several crops. Its damage can be direct and indirect. The direct damage is due to its feeding, which causes leaf shriveling, deformation of shoots, and loss of plant vigor. The pest’s indirect damage is through virus transmission to cotton. In Brazil, A. gossypii is considered as a pest to several crops, but there are no references to infestations of this aphid in soybeans. The objectives of this manuscript were to report the presence of A. gossypii infesting and colonizing soybean crops in São Paulo state, Brazil, and to alert the scientific community and farmers about this possible new pest in Brazilian soybean fields.

A polyphagous and cosmopolitan species, the aphid Aphis gossypii Glover (Hemiptera: Aphididae) is a serious pest to several crops because it infests economically important plants of the families Asteraceae, Cucurbitaceae, Malvaceae, Rutaceae, and Solanaceae (BLACKMAN; EASTOP, 2006;CABI, 2022).Its damage can be direct, due to its feeding, which causes leaf shriveling, deformation of shoots, and loss of plant vigor, and indirect, mainly through virus transmission.Worldwide, A. gossypii is recognized as the transmitter of more than 30 viruses to different crops (EBERT; CARTWRIGHT, 1997;CABI, 2022), and it is the only known vector in the transmission of the polerovirus cotton leafroll dwarf virus to cotton (COSTA et al., 1997;MAHAS et al., 2022).
In Brazil, A. gossypii is known as a pest to cotton, cashews, papaya, several cultivated cucurbits, gladioli, and okra.It also acts as a virus carrier for cotton and citrus (ROISTACHER et al., 2010;GALBIERI et al., 2017).However, there are no references to infestations of this aphid in soybeans.Thus, the objective of this document was to report on its presence, infestation, and colonization in soybean crops in São Paulo state, Brazil.
In May 2019, aphid infestation was observed on the leaves of the soybean plants (Fig. 1) in a 1-hectare area of soybean (cv.NA 5909 RG) in the town of Pereiras, São Paulo, Brazil (557 m elevation, 23°08'56"S, 47°57'36"W).The infestation was well distributed among the soybean plants and present throughout the entire area where the oilseed was grown.Leaves in the middle third of the plants presented aphid colonies in large numbers.During the capture of the aphids, it was observed that there were cotton plants at the end of their phenological cycle in adjacent areas.This probably made it possible for the aphids (previously fed on the sap of the cotton plants) to move from this crop and colonize the soybean plants.
DNA extraction, polymerase chain reaction (PCR) amplification, and sequencing Sanger of the collected aphid specimens (nymphs and adults) were performed for identification.Insects were macerated, and DNA was extracted using 10% Chelex resin and proteinase K (20 mg/mL).The mitochondrial cytochrome oxidase I (COI) gene was amplified (SIMON et al., 1994;LAGOS et al., 2012).The PCR mix used was 12.5 uL gotaq, 1 uL of each primer, and 3 uL of DNA completed with water for a final reaction of 25 uL.The thermal cycler protocol used to amplify COI was 95°C 2 min (95°C,30 s; 53°C,30s; 72°C,120s) 40x.The PCR products were run on a 1% agarose gel.In the PCR products that obtained amplified bands, DNA purification was performed with the aid of magnetic beads.The amplified fragments Reports of A. gossypii colonization on soybeans are rare.However, there have been reports of this happening.On the African continent, this aphid was collected from soybeans in Zambia (LAGOS-KUTZ; HARTMAN, 2021).In North America, A. gossypii has been reported to colonize soybeans (BLACKMAN; EASTOP, 2007).In the north-central United States of America, its colonization on this legume also appears to be uncommon, but aphid samples collected on soybeans in Alabama, Georgia, Kansas, Louisiana, and Mississippi contained only A. gossypii alone or in mixture with Aphis glycines Matsumura (Hemiptera: Aphididae).This suggests that A. gossypii may be more common on soybeans in southern regions of the United States of America (LAGOS-KUTZ et al., 2014).
Up to now, there have been no reported infestations of A. gossypii on soybean in Brazil.However, there are extensive areas of soybean cultivation in different Brazilian regions, often near areas of cotton crops, which is a favorite host for this aphid.Thus, after finding this infestation, in Brazilian regions where cotton and soybeans are planted in successive plantings, A. gossypii has become, from the present record, an insect that will need greater attention from the scientific community due to its potential to colonize and cause damage to soybeans.

Figure 1 .
Figure 1.Aphis gossypii colony.(a) Wide view of colonies of Aphis gossypii observed on soybean leaves; (b) nymphs of Aphis gossypii observed with magnifying glass.Source: Elaborated by the authors.