Nothotrioza myrtoidis

Carneiro, Renê G. S., Burckhardt, Daniel & Isaias, Rosy M. S., 2013, Biology and systematics of gall-inducing triozids (Hemiptera: Psylloidea) associated with Psidium spp. (Myrtaceae), Zootaxa 3620 (1), pp. 129-146 : 138

Biology of N. myrtoidis

Psidium myrtoides is an evergreen plant which has little demarcation of leaf flushing, maturation and senescence phenophases ( Fig. 5 A). Mature leaves are found throughout the year in all individuals of the population. A variable number of individuals presents senescence and their leaves fall along the year. In October 2009, all the analysed individuals showed leaf senescence, coinciding with the more pronounced phenological activity of budburst in this population. Leaf flushing decreased but persisted in a smaller portion of the population throughout the year.

The induction of the galls by Nothotrioza myrtoidis began in October and lasted until early December. Gall growth and development started in November and lasted until September of the following year. In early August, some galls reached maturation, which lasted until November when the peak of senescent galls was registered ( Fig. 5 B). In October of 2009 and 2010, during leaf flushing, two events of induction were observed, reaching infestation rates ??of 30.3 % and 17.2 %, respectively.

The second instar nymphs were found in 90 % of the galls from November 2009 to February 2010. In March they were reduced to about 80 %, and reached the lowest percentage in July. The highest percentage of occurrence of the third instar was registered in April (approximately 80 %), while the fourth and fifth instars from May to June and from July to September, respectively. From August to October, adults were found inside the galls, and by the end of this period, the life cycle of the insects restarted ( Fig. 6 ). The first instar nymphs were not counted because they were located on the leaf surfaces and became usually detached during handling and fixation of the leaves. There was a positive correlation between the volume of the galls and the nymph developmental stages (r = 0.89), which formed five groups ( Table 2 ).

The development of N. myrtoidis passes through five nymphal stages, taking one year to complete its whole life cycle. Females lay their eggs strictly on the margins of young leaves of P. m y r t o i d e s. The first instar nymphs ( Fig. 7 A) emerge and migrate to the limb, where they settle and begin to feed. Inside the galls, the nymphs pass through successive developmental stages until the fifth instar ( Figs 7 B–E), which is the predecessor of the adults. These are distinguished from the nymphs mainly by the presence of functional wings ( Fig. 7 F). Females can be distinguished from males in the morphology of the terminalia. Females possess a short, cuneate ovipositor ( Fig. 7 F, detail on the left) whereas males are characterised by the tubular proctiger and the subglobular subgenital plate with the papameres and aedeagus ( Fig. 7 F, detail on the right).

Nymphs of Nothotrioza myrtoidis were parasitized by an undescribed species of Galeopsomyia ( Hymenoptera : Eulophidae ) ( Fig. 7 G, arrow). When pupating ( Fig. 7 H) the parasitoid ends its feeding activities, having caused the death of the gall inducer. Galeopsomyia sp. uses the gall as shelter during the development period until the adult stage ( Fig. 7 I), when it actively digs an escape tunnel, reaching the external environment ( Fig. 7 I, detail). The gall inducers presented 15.7 % of parasitism and 29.8 % of mortality, along the insect’s life cycle. A relationship between the red colour of the gall and the non-parasitized condition of the gall inducer was found (χ2 = 10.67; p = 0.0048) ( Fig. 8 ).

Figures

FIGURE 5. Vegetative phenology of Psidium myrtoides (Myrtaceae) (A), and globoid galls induced by Nothotrioza myrtoidis (Psylloidea: Triozidae) (B) during a 1 - year cycle. G & D—Growth and development, I—Induction, LF—Leaf flushing, M—Maturation, S—Senescence

FIGURE 6. Life cycle of Nothotrioza myrtoidis (Psylloidea: Triozidae). N 1 — First instar nymphs; N 2 — Second instar nymphs; N 3 — Third instar nymphs; N 4 — Fourth instar nymphs; N 5 — Fifth instar nymphs; A—Adults.

FIGURE 7. Nothotrioza myrtoidis (Psylloidea: Triozidae) A – E. Five instar nymphs. F. Adult female. In detail, short cuneate ovipositor (detail on the left), and tubular proctiger and the subglobular subgenital plate with the papameres and aedeagus of the male (detail on the right). G. Parasitized nymph. H – I. Galeopsomya sp. H. Pupae. I. Adult. In detail, gall with the opening of an escape tunnel.

FIGURE 8. Relationship between the colour of the gall and the status of the gall inducer. Data submitted to chi-square test.