Dysmicoccus neobrevipes
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| Beardsley , 1959 |
Dysmicoccus neobrevipes is a scale insect from the family of mealybugs (Pseudococcidae). It is, together with the pineapple plant louse ( Dysmicoccus brevipes ), one of the economically most important pests on pineapple plants .
features
The adults have a wide, oval-shaped body that is about 0.1 millimeters wide and 0.15 millimeters long. They have a brown to grayish-orange body color, but appear gray due to wax excretions. The back is heavily covered with many fine tufts of wax. Wax threads are found all around the body. The ones on the sides are half as long as the ones behind, which reach about half the length of the body. The females look very similar to those of the pineapple marmoset, which is why they were collectively seen as a two-breed species. It was not until 1959 that Beardsley realized that these were two separate species.
The adult males are winged and differ from the pineapple gub by 10 instead of eight antennae and by the hair, the hairs of which, unlike the similar species, do not end up getting thicker.
The larvae are the dispersal stage of the species. They have a flattened body with long hair that allows them to be drifted by the wind.
Occurrence
Dysmicoccus neobrevipes is pantropically distributed over the entire tropics . You can also find them sporadically in the subtropics. The animals can be found in all regions in which the pineapple is grown, especially in the Fiji Islands , Jamaica , Hawaii , Malaysia , Mexico , Micronesia , the Philippines and Taiwan .
Way of life
In addition to pineapple plants, the species attacks numerous other plants such as sweet acacia ( Acacia farnesiana ), pear apple tree ( Manilkara zapota ), net annone ( Annona reticulata ), bananas ( Musa ), Opuntia megacantha , Pipturus argentea , Piscidia piscipula , Samanea saman , sisal ( Agave sisal ), Cocoa tree ( Theobroma cacao ) and tuberose ( Polianthes tuberosa ). Unlike the related species, it is not found on grass.
The animals usually sit on leaves, branches, aerial roots, flowers and fruits of the food plants. This is how they differ from the pineapple gub, which is mainly found on the plant base.
development
Like the related species, the females do not lay eggs, but give birth to living larvae that have previously developed inside the mother. In the first 26 days the females do not give birth to any larvae, after which they lay an average of 350 offspring for about 30 days, the maximum number is about 1000. After that, they only live for about four days and die. The lifespan of an adult female varies between 48 and 72 days, the average is 61 days.
The life expectancy of female Dysmicoccus neobrevipes is between 59 and 117 days, on average 90 days. The females go through three larval stages before they molt into an adult. The three stages last 11 to 23, 6 to 20 and 7 to 28 days, the average duration is a total of around 35 days. The larvae only eat in the first and the beginning of the second stage. The males go through an additional larval stage. You need 11 to 19, 7 to 19, 2 to 7 and 2 to 8 days for the respective stages, the total duration is between 22 and 53 days. The male adults only live very short and die after two to seven days.
Harmful effect
The species is an economically important pest on pineapple plants. It is one of the causes of pineapple wilt: it makes the plants susceptible to saprobiotic organisms or makes them dry up. Another damage caused by mealybugs is called green spot disease : the excretions of the scale insects attack the leaf tissue and create dry spots similar to plant gall.
An important criterion for the spread of a colony of Dysmicoccus neobrevipes and the associated damage is the presence of ants , which not only milk the honeydew that the animals excrete, but also defend the colonies from predators and parasites.
Natural enemies and combat
Natural enemies are a number of parasitic wasps such as Aenasius cariocus or Anagyrus ananatis or predators such as the ladybirds Cryptolaemus montrouzieri , Scymnobius bilucernarius , Scymnus unicatus or Scymnus pictus and gall flies such as Lobodiplosis pseudococci . However, these cannot contain a strong infestation of mealybugs, as these are usually protected by ants.
In order to prevent an infestation of plantations, the ants are primarily fought. The edge of the fields is mowed so that ants can find little food and ant fences are put in place. Although these do not form a barrier against ants, they prefer to climb along the wire instead of crossing the fence. Finally, there is also the option of combating ants with pesticides. A field already infested with mealybugs must be cleared and plowed. All plants growing on it are burned beforehand.