Spatial Distribution of Nymphs of Triozoida limbata Enderlein, 1918 (Hemiptera: Triozidae) in Guava Orchards

Abstract

Triozoida limbata is considered one of the leading pests of guava crop in Brazil. Its nymphs are responsible for sucking leaf borders, causing curling and drying of the leaves, and leaving them with a necrotic appearance. Knowledge of the spatial distribution of nymphs of T. limbata is essential for improving sampling and control techniques. The objective of this study was to perform probabilistic analyses of patterns of spatial distribution of nymphs of T. limbata in guava orchards. The study was conducted in four guava orchards in Ivinhema, Mato Grosso do Sul, Brazil. Samplings were performed every 15 days, from April 2012 to March 2014. To obtain the nymph counts, a sampling area was demarcated in each orchard, comprising 50 sampling units. In each unit, a sample was taken randomly from a shoot of 10 cm to 15 cm in length at the median height of the central plant. Dispersion rates were calculated (variance/mean ratio, Morisita index, and Exponent k of Negative Binomial Distribution) and the data obtained in the field were adjusted to the theoretical frequency distributions (Poisson and Negative Binomial). Following the analyses, we concluded that nymphs of T. limbata in the studied populations were randomly organized in the four areas that were evaluated, and the sampling data have been adjusted to the Poisson distribution model.

Repellency of selected Psidium guajava cultivars to the Asian citrus psyllid, Diaphorina citri

“…The research presented here confirms that guava leaves have repellency to ACP and is the first study to show that extracts of oil from the leaves of five different guava cultivars have repellent activity. One of the cultivars, 'J3', is known to have repellency to Triozoida limbata, a psyllid that causes severe damage to some guava cultivars in Central and South America (Sá and Fernandes 2015).…”

Electrostatic spraying in the chemical control of Triozoida limbata (Enderlein) (Hemiptera: Triozidae) in guava trees (Psidium guajava L.)

“…The colonies of this pest are located between droplets of sugary substances within the leaf margins of the guava tree and are covered by a waxy secretion. Owing to the sap suction and the toxins injected into the leaf margins, the psyllids cause curling of the edges of the leaf blades, yellowing, necrosis and leaf drop, which compromises production …”

Antixenosis of the Triozid, Triozoida limbata (Hemiptera: Triozidae) to Some Cultivars of Psidium guajava (Myrtaceae) in the Field

“…The guava crop, Psidium guajava L. (Myrtaceae), despite its growing economic importance in Brazil (Pereira et al 2017), has productivity reduced due principally to the occurrence of some key pests (Souza Filho & Costa 2003), such as the triozid Triozoida limbata (Enderlein) (Hemiptera: Triozidae) (Burckhardt & Queiroz 2012;Sá & Fernandes 2015;Queiroz et al 2018).…”