Australian Fruitworm

Reproduction

"Helicoverpa punctigera" egg are spherical in shape and 0.5 millimetres in diameter. While its colours vary based on the stage of larval development. While originally white, the eggs will change to brown and finally black just before hatching.Newly hatched larvae are observed to be 1–2 millimetres in length and will grow up to 40 millimetres in length. Observed to be various shades of brown, green and orange, the larvae's colour darkens as it matures and the dark spots on it become more apparent. The "H. punctigera" larva's body is covered in small bumps, long stiff back hairs and bristles that cover its body and there are black hairs around the head."Helicoverpa punctigera" egg are spherical in shape and 0.5 millimetres in diameter. While its colours vary based on the stage of larval development. While originally white, the eggs will change to brown and finally black just before hatching.Newly hatched larvae are observed to be 1–2 millimetres in length and will grow up to 40 millimetres in length. Observed to be various shades of brown, green and orange, the larvae's colour darkens as it matures and the dark spots on it become more apparent. The "H. punctigera" larva's body is covered in small bumps, long stiff back hairs and bristles that cover its body and there are black hairs around the head.Belonging to the insecta class of animals, the "H. punctigera" follows an oviposition behaviour where it expulses its eggs by a vertebrate. Oviposition is the expulsion of eggs from the female insecta's oviduct to an external environment. While the Oviposition behaviour is unrelated to the feeding habits of the female "H. punctigera", the female "H. punctigera" tends to lay its eggs in areas with more flowering crops than in other areas. This is mainly due to the female "H. punctigera" feeding habits as the food chain is crucial in the reproductive cycle of the "H. punctigera". Any factors affecting the food supply during their reproduction period would determine the reproductive potential of the "H. punctigera" specials. Despite the "H. punctigera" feeding habits however, the female "H. punctigera" is able to lay its eggs anywhere and at any time of day.

The selection of area is also crucial to the survival of the eggs and larvae of the "H. punctigera". Selecting an area in the open will lead to the eggs and larvae being susceptible to various predatory insects and animals. Furthermore, selecting an area without sufficient food would mean that the larvae would not have enough to feed on as well.

Food

"H. punctigera" particularly feed on high value crops such as cotton, soybean, maize, and tomato and various other horticultural hosts.

In the early larvae stages, the "H. punctigera" feed on seeds and damage plant pods while in the mid to late stages of development, the larger "H. punctigera" larvae is able to consume entire plant pods and their contents.

Predators

Spiders and Predatory insects including various species of ants, predatory beetles, predatory bugs and lacewings often feed on the "H. punctigera" genus of moth. While a proportion of the "H. punctigera" predators do not specifically prey on the "H. punctigera", certain predators’ prey on specific life stages of the "H. punctigera".

Various parasitoids attack the "H. punctigera" at various life stages. These parasitoids slowly kill their host by feeding off its nutrients effectively slowing the rate of larvae feeding resulting in lower rate of crop damage. Parasitoids that attack the "H. punctigera" include the "Trichogramma" and "Ichneumon" genera of wasps and "Cacelia" genus of flies.

Wasp Parasitoids spread ascovirus to larvae staged "H. punctigera" stunning their growth. Other natural occurring diseases that kill the "Helicoverpa" larvae include fungal pathogens, Nuclear Polyhedrosis Virus and "Bacillus thuringiensis" which creates proteins that are toxic to the larvae when consumed. Some genetically modified bacterial pathogens are used in commercial biopesticides. A popularly used pathogen is "Bacillus thuringiensis" which mainly kills larval Lepidopterans when consumed. It is used in pesticides and when genetically modifying cotton plants.

Migration

"Helicoverpa punctigera" is capable of long-range migration at high altitudes ) over host crops ) in addition to entire regions ). With long-distance flight being possible for the "H. punctigera", their habitats are generally observed to be temporary once the "H. punctigera" reaches the adult stage of the life cycle. It is noted that the "H. punctigera" are found in abundance in the far inland and around the coast of Australia during the summer period. This is heavily due to the climate being favourable for the reproduction in summer.

As of 2010 there was research regarding the migration of the "H. punctigera", but it was difficult to test for the back-migration of "H. punctigera". That was primarily due to there being a gradual migration of the population and there being no appropriate markers to track individual "H. punctigera". As of 2019 tracking had been greatly improved by advances in radar, population genetics markers, and dispersal modeling.

Cultural

While in the larval stage, "H. punctigera" cause farmers to lose millions of dollars’ worth of crops due to their polyphagous eating habits. They prefer eating mostly broadleaf species of plants such as cotton, chickpea and various native herbs in addition to a broad selection of other various pastures. The further the "H. punctigera" larvae are in the growth stage, the more the larvae consume. When in the 5th and 6th instars, the "H. punctigera" larvae consume 90% of the grain consumption the "H. punctigera" consumes in its life cycle.

When the "H. punctigera" consumes crops, chewing damage and holes can be observed on the plant pods and seed heads.