Hyblaea puera, commonly known as the teak defoliator, is a moth

Moth

A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...

 native to southeast Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

. The species has also been recently reported to be present in Central America

Central America

Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

 and Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

. The caterpillar

Caterpillar

Caterpillars are the larval form of members of the order Lepidoptera . They are mostly herbivorous in food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered to be pests in agriculture...

 feeds on teak

Teak

Teak is the common name for the tropical hardwood tree species Tectona grandis and its wood products. Tectona grandis is native to south and southeast Asia, mainly India, Indonesia, Malaysia, and Burma, but is naturalized and cultivated in many countries, including those in Africa and the...

 and other species of trees common in the region.

Distrubution and habitat

Hyblaea puera occurs in forests across southern Asia from India and Bangladesh, through Thailand and the rest of Southeast Asia to New Guinea, and north Queensland in Australia. Recent reports place it in Guadeloupe

Guadeloupe

Guadeloupe is an archipelago located in the Leeward Islands, in the Lesser Antilles, with a land area of 1,628 square kilometres and a population of 400,000. It is the first overseas region of France, consisting of a single overseas department. As with the other overseas departments, Guadeloupe...

, and Surinam.

Life cycle

The adult moths are comparatively small, with a wing span of 3 – 4 cm, and have a characteristic resting posture that conceals the black and orange-yellow hind wings under the grayish-brown fore-wings. Males and females emerge more or less simultaneously and mating takes place within a couple of days. Eggs are laid on tender new leaves, placed singly near the veins, and usually on the undersurface. They are oval, flat, and white and measure about 1 mm in length. About 500 eggs are laid per female with a recorded maximum of 1000. Larvae hatch in about 2 days. There are five larval instars. The first and second instars mainly feed on the leaf surface. Starting with the third instar, the larva cuts out a leaf flap, usually at the edge of the leaf, folds it over, fastens it with silk, and feeds from within. The entire leaf, excluding the major veins of tender leaves, is eaten, but more veins are left in older leaves. Under the optimal conditions, the larval period lasts 10–12 days. The full grown larva measures about 3.5 – 4.5 cm, and there is considerable color variation in the fourth and fifth instars; the body may be either wholly black or dark grayish to black, with longitudinal colored bands may include a dorsal orange or ocherous band and lateral white lines. The mature larvae descend to the ground on silken threads and pupate under a thin layer of leaf litter or soil, with in loosely built cocoons made of dry or decayed leaves, or soil particles held together with silk. Pupation may some times occur with in green leaves of other plants in the under growth, folded or juxtaposed with silk. On Avicennia plants the caterpillars pupate inside the cases made out of the host plant leaves itself. It is probably an adaptive trait acquired by the species for surviving in the hostile mangrove environment, since the pupation is not possible in the muddy and inundated soils of mangroves. The average pupal period lasts six to eight days under optimal conditions. There is no evidence of hibernation or aestivation of pupa.

Temporal and Spatial dynamics

The teak defoliator is present the year round in teak plantations, but in varying population densities. During the period of natural defoliation of teak (November, December, January), the pest density is very low (endemic). Every year high intensity outbreaks of teak defoliator occurs immediately after the pre monsoon showers in late February or early march in Kerala

Kerala

or Keralam is an Indian state located on the Malabar coast of south-west India. It was created on 1 November 1956 by the States Reorganisation Act by combining various Malayalam speaking regions....

. These epicenters are highly localized outbreaks which represents the transitional stage between very sparse endemic population and high density outbreak population. These epicenters will be 5,000 to 15,000 square metres in area and are characterized by heavy tree top infestation. The months of April, may, June and July witness a series of large outbreaks. During late July or September, the population declines to the endemic level. In some years, there will be fresh outbreaks during the month of October. From then on until the next year, the population remains at the endemic level.

Parasitoids

The main parasitoids attacking teak defoliator include the tachinid

Tachinidae

Tachinidae is a large and rather variable family of true flies within the insect order Diptera, with more than 8,200 known species and many more to be discovered. There are over 1300 species in North America. Insects in this family are commonly called tachina flies or simply tachinids...

 Palexorisa solennis, a eulophid

Eulophidae

Eulophidae is a large family of hymenopteran insects, with over 4,300 described species in some 300 genera . The family as presently defined also includes the genus Elasmus, which was previously treated as a separate family, "Elasmidae", and is now treated as a subfamily of Eulophidae...

 Sympiesis hyblaeae, the chalicid

Chalcididae

The Chalcididae are a moderate-sized family within the Chalcidoidea, composed mostly of parasitoids and a few hyperparasitoids. The family is apparently polyphyletic, though the different subfamilies may each be monophyletic, and some may be elevated to family status in the near future. As...

  Brachymeria lasus  and the three ichneumonids

Ichneumonidae

Ichneumonidae is a family within the insect order Hymenoptera. Insects in this family are commonly called ichneumon wasps. Less exact terms are ichneumon flies , or scorpion wasps due to the extreme lengthening and curving of the abdomen...

, Eriborus gardneri, Stictopisthus sp.,and Echthromorpha agrestoria notulatoria. B. lasus is a pupal parasitoid and all others are larval parasitoids. The overall parasitism by all species is about 9%.

Predators

Predatory insects including wasps, spiders, birds and Bonette macaque are known to comprise the predator complex of H. puera. Forty eight species of birds have been recorded as feeding on teak defoliator larvae during the large scale outbreaks.

Pathogens

The bacteria Enterobacter aerogenes

Enterobacter aerogenes

Enterobacter aerogenes is a Gram-negative, oxidase negative, catalase positive, citrate positive, indole negative, rod-shaped bacterium....

, Bacillus thuringiensis

Bacillus thuringiensis

Bacillus thuringiensis is a Gram-positive, soil-dwelling bacterium, commonly used as a biological pesticide; alternatively, the Cry toxin may be extracted and used as a pesticide. B...

, Pseudomonas aeruginosa

Pseudomonas aeruginosa

Pseudomonas aeruginosa is a common bacterium that can cause disease in animals, including humans. It is found in soil, water, skin flora, and most man-made environments throughout the world. It thrives not only in normal atmospheres, but also in hypoxic atmospheres, and has, thus, colonized many...

 and Serratia marcescens

Serratia marcescens

Serratia marcescens is a species of Gram-negative, rod-shaped bacterium in the family Enterobacteriaceae. A human pathogen, S. marcescens is involved in nosocomial infections, particularly catheter-associated bacteremia, urinary tract infections and wound infections, and is responsible for 1.4% of...

 are identified as causing mortality to the teak defoliator. A synnematous fungus of the genus Hirsutella

Hirsutella

Hirsutella is a genus of asexually reproducing fungi in the Ophiocordycipitaceae family. Originally described by French mycologist Narcisse Théophile Patouillard in 1892, this genus includes species that are pathogens of insects, mites and nematodes; there is interest in the use of these fungi as...

 is found to be pathogenic to this pest. An absolutely specific virus with refractile polyhedral inclusion bodies, staining blue in Giemsa and thick blue in Buffalo black, named as Hyblaea puera Nucleopolyhedrovirus (HpNPV) is found to be very effective in the biological control of this pest.

Hyblaea puera Nucleopolyhedrovirus (HpNPV)

Large scale deaths of teak defoliator larvae characterized by cessation of feeding, flaccidity and subsequent liquefaction of body tissues has been reported by Stebbing as early as 1903. During 1985, an investigation on microbial pathogens of H. puera was undertaken in the plantations of Nilambur Forest Divisions of Kerala, India by KFRI detected several dead insects with the characteristic symptoms as observed by Stebbing. Microscopic observation of tissues revealed the presence of refractile polyhedral inclusions bodies, which stained blue in Giemsa, and measuring 0.9 – 2.4 micrometers in diameter in the scanning Electron Micrograph taken by Jean Adams at USDA, confirmed its identity as NPV. The NPVs come under the family of baculoviridae and its virions are enveloped rod shaped nucleocapsids containing circular, supercoiled, double stranded DNA.

Mode of action

The NPV which enters the insect gut, lyses in the alkaline environment of the midgut, releasing virions. Virions invade the columnar cells of midgut epithelium and integrate DNA into the nucleus of midgut cells. Later the viral DNA takes over control of the cellular machinery to reproduce itself. The ECVs which are the progenies released into the haemocoel from the midgut cells are more infectious than the PIBs and mediate disease spread within the insect body. A rapid spread of infection in the insect body leads immediately to cessation of feeding and later on, to death. Even in the fully mature larvae, HpNPV can cause a kill in 60–72 hours, making it one of the fastest acting insect viruses.

The discovery of virus disease on H. puera was a major break through in the teak defoliator management research.