Botanicals, selective insecticides, and predators to control Diaphorina citri (Hemiptera: Liviidae) in citrus orchards

Abstract

The Asian citrus psyllid (ACP) Diaphorina citri Kuwayama vectors pathogens that cause huanglongbing (HLB) or citrus greening devastating and economically important disease present in most citrus growing regions. Young citrus shoots are required for psyllid reproduction and development. During winter citrus trees produce little or no new growth. Overwintering adults reproduce in spring on newly emerging shoots also attractive to other pests and beneficial insects. Botanicals and relatively selective insecticides could help to conserve beneficial insects and reduce pest resistance to insecticides. Sprays of Azadirachtin (Neem), Tropane (Datura), Spirotetramat, Spinetoram, and broad-spectrum Imidacloprid were evaluated to control ACP in spring and summer on 10-year-old "Kinow" Citrus reticulata Blanco trees producing new growth. Psyllid populations were high averaging 5-9 nymphs or adults per sample before treatment application. Nymphs or adults were significantly reduced to 0.5-1.5 per sample in all treatments for 3 weeks, average 61%-83% reduction. No significant reduction in ladybeetles Adalia bipunctata, Aneglei scardoni, Cheilomenes sexmaculata, and Coccinella septempunctata was observed. Syrphids, spiders and green lacewings were reduced in treated trees except with Tropane. Studies are warranted to assess impact of these predators on ACP and interaction with insecticides. Observed reduction in ACP populations may not be enough considering its reproductive potential and role in the spread of HLB. Follow-up sprays may be required to achieve additional suppression using rotations of different insecticides.

Efficacy of essential oil of Piper aduncum against nymphs and adults of Diaphorina citri

“…Regarding the efficacy of topical application against adults, we observed that various concentrations of dillapiol in OPA at different dilutions were effective for control of D. citri (mortality between 70 and 98%). Other studies showed that neem extract at 1% dilution caused 80% mortality and reduced the number of adults on leaves by up to fourfold compared with untreated areas . Similarly, a 1% dilution of D. alba extract reduced the number of D. citri adults on leaves by up to fourfold compared with untreated areas .…”

“…Other studies showed that neem extract at 1% dilution caused 80% mortality and reduced the number of adults on leaves by up to fourfold compared with untreated areas. 12,13 Similarly, a 1% dilution of D. alba extract reduced the number of D. citri adults on leaves by up to fourfold compared with untreated areas. 13 Efficacies of P. aduncum extract against adults of the sucking insects Aetalion sp.…”

“…Khan et al reported 80% mortality of adult psyllids in the field using neem extract. Neem and Datura alba Nees extracts reduced the number of D. citri nymphs and adults by up to fourfold compared with untreated areas in field conditions …”

“…Neem and Datura alba Nees extracts reduced the number of D. citri nymphs and adults by up to fourfold compared with untreated areas in field conditions. 13 Piper aduncum L., a plant abundant in the Amazon region, displays insecticidal properties 14 because it contains secondary metabolites that show toxicity towards insects, especially monoterpenes, 15 sesquiterpenes 16 and phenylpropanoids, 17 with the phenylpropanoid dillapiol being the major compound. 18 -20 Dillapiol potentially inhibits the activity of cytochrome-P450dependent monooxygenase, which transforms lipophilic compounds into more soluble (hydrophilic) and easily excretable products.…”

Absence of windbreaks and replanting citrus in solid sets increase density of Asian citrus psyllid populations

“…Depending on the size of the orchard, 10 trees represented between 22% and 43% of the total edge. Additionally, beginning on the 29th of May 2015, the numbers of ladybeetles (Coleoptera: Coccinellidae), lacewings (Neuroptera: Chrysopidae), spiders (Araneae), which are predators of D. citri in Florida (Khan et al, 2014;Monzo et al, 2014), were collected and noted.…”