Ploetzia amygdalis Mabille, 1877

Cock, Matthew J. W., Congdon, Colin E. & Collins, Steve C., 2014, Observations on the biology of Afrotropical Hesperiidae (Lepidoptera). Part 6. Hesperiinae incertae sedis: palm feeders, Zootaxa 3831 (1), pp. 1-61 : 5

Ploetzia amygdalis Mabille, 1877

Mabille (1877) described Hesperia amygdalis in a footnote to his paper on the Hesperiidae of Congo, based on two specimens from Nosy Bé (as Nossi-Bé) and Madagascar. Adults have been collected at light more recently at Nosy Bé (specimens in ABRI). Published reports are restricted to the north and east of Madagascar.

Food plants. There have been reports of this species feeding on coconut, Cocos nucifera ( Viette 1956, Mariau 2001), but the life history has not previously been documented. ABRI collectors have found caterpillars on C. nucifera on Île Ste Marie, off the east coast of northern Madagascar ( Figure 1–2 ), as well as a caterpillar and pupa on the indigenous golden palm, Dypsis lutescens , at Antsiranana (Diego-Suarez) and Montagne des Français respectively, in the far north, and emerged pupae (1♂, 2♀) on a Raphia sp. palm at Ranomafana, in the south-east of Madagascar.

Life history. The ova are laid in longitudinal rows on a palm leaflet, touching each other. They are 1.9mm in diameter (9 eggs = 17mm), dome-shaped with about 54 fine ribs. The eclosing caterpillar eats most but not all the shell apart from the base.

The caterpillars ( Figure 2.1–2 ) are unusual in that they are gregarious in the early instars ( Figure 2.2 ) and do not make leaf shelters. In the final instar ( Figure 2.1 ) the caterpillars disperse, and make individual rolled leaflet shelters, in which they pupate ( Figure 1.1 ). The pupa ( Figure 2.3 ) is 29–32mm long, brown, smooth, without projections, the proboscis barely projecting beyond the wing cases. The inside of the shelter and the pupa are both lightly covered with white waxy powder.

Natural enemies. In one row of nine eggs, four had emergence holes of an egg parasitoid; in another of seven eggs all emerged normally. Pupae were parasitized by a large, solitary yellow-brown ichneumonid parasitoid; it emerged by pushing off the head of the pupa along suture lines, rather than cutting a hole in the cuticle. Other fieldcollected pupae had round parasitoid emergence holes compatible with a Brachymeria sp.

Figures

FIGURE 1. Feeding damage and adults of Ploetzia amygdalis on Cocos nucifera, 21 Nov 2006, Île Ste Marie, Madagascar [SCC]. 1, Feeding damage by caterpillars; 2–3, reared adult male.

FIGURE 2. Caterpillars and pupa of Ploetzia amygdalis, collected as caterpillars on Cocos nucifera, Île Ste Marie, Madagascar, 21 Nov 2006, [SCC]. 1, final instar caterpillar, dorsal view; 2, early instar caterpillars in a gregarious group; 3, pupa, dorsolateral view.