رویان

بزرگترین مجله کشاورزی اینترنتی

رویان

بزرگترین مجله کشاورزی اینترنتی

Beetles سوسک ها

Ladybird beetles, also known as ladybug beetles are voracious predators of aphids. Collectors sell them in bulk to gardeners for pest control. Beetles can be both enemy and friend to the agriculture industry. Some species devastate crops and others attack the attackers which reduces the need for chemical pesticides.

This is a close up of the Lady bugs laying her eggs.

The group of insects known as beetles are members of the family Scolytidae in the order Coleoptera. Most beetles cause little or no economic damage as they normally infest branches, stumps, and stems of standing dead, severely weakened trees or downed material. A relatively few species will attack and kill living, apparently healthy trees. Beetles are integral components in forest ecosystems and therefore can be viewed as beneficial or detrimental depending on the management objectives.

4,000 different mammals and 9,000 birds only add up to less than 1% of the 1.75 million species identified by science. Insects make up about 60% and at least a third of them are in the order Coleoptera - the beetles.

A variety of approaches are available to reduce the amount of mortality caused by beetle outbreaks. Detection methods, treatment selection and application, and other management activities vary for individual beetle species.

All three species of beetles are similar in appearance through all their life stages. Main differences between the species are in size, tree species attacked, and timing of parts of the life cycle. Life stages for bark beetles are described below:

Egg: pearly white, oblong, 0.75–1.0 mm long. Eggs are laid in individual niches or elongate grooves on alternate sides of the egg gallery.

Larva: creamy white, cylindrical, stout, wrinkled, legless grub, 6–7 mm long at maturity (fourth instar). Head is pale tan to pale rusty.

Pupa: creamy white, approximately 6 mm long, becoming pale tan near maturity. Pupae have legs and maturing wings that are visible.

Pupa state

Adult: immature, or callow, adults after transforming from pupae are initially white and then medium brown. Mature adults are mostly all black or have rusty colored wing covers. Adults are approximately 6 mm long.

Distribution and host range

In general, the distribution of each species of beetle follows the distribution of its primary host.

Life cycles and dynamics

The life cycles of the beetles are similar with some variation in timing and effect. Also, while the mode of action in killing individual trees is the same for all three species, affected trees vary in their display of symptoms. It is necessary to know the differences when identifying the causal agent, establishing where the infestation is in its cycle, and for selecting the most appropriate treatment prescription.

Romance begins at arm's length for two harlequin beetles. They gingerly check each other out with their oversize limbs in a courtship ritual.

Life cycles

All three beetle species have similar life cycles, progressing from egg, through four larval instars, to pupa, and finally to adult. The life stages for each insect closely resemble each other; however, differences in timing and duration affect the selection and application of management tools. The timing of various components of the life cycles are summarized in Table 2. The timing of life cycle events for any species of bark beetle will vary from year to year and from location to location due to variations in climate and local weather.

A brief synopsis of the life history of all three beetle species is as follows:

1.Adult females emerge when ambient air temperature exceeds approximately 16* C, find new suitable host material, and emit aggregating pheromones to initiate mass attack.

2.Males join the females and each pair construct an egg gallery under the bark, parallel to the grain.

3.The sapwood is inoculated with spores of a blue stain fungus as the egg gallery is built.

4.Eggs are laid and hatch into larvae which feed on the phloem in feeding channels constructed at right angles to the egg gallery.

5.After four instars, larvae pupate and develop into adults under the bark.

6.Young adults pick up blue stain fungal spores while in the pupa chamber.

The action of the larval feeding in the phloem and fungal colonization of the sapwood completely blocks all translocation tissues and kills the infested tree. In some cases only one side of a tree will be successfully attacked (strip attack); this tree will survive unless living portions are attacked again in subsequent years.

The scarab beetle is essential to ecosystems. These beetles recycle plant matter and feces. Though some are brilliantly colored, it was a black dung beetle that the ancient Egyptians revered as a symbol of rebirth.

Symptoms of successful attack

Successfully attacked trees display symptoms that are utilized in ground and aerial surveys. Other bark beetle species may be found under the bark of trees. Identification of these usually lesser important beetles is done by examining egg gallery patterns and adult morphology which differ significantly from the major bark beetles. Adults and larvae of wood borers may also be found under the bark or on the boles of trees. Proper identification of the insect is necessary to ensure that the appropriate management strategy is selected.

The impact of bark beetles is not limited to timber loss. There are also impacts upon a variety of other resource values, which include:

•range

•recreation

•cultural heritage

•fish and wildlife

•watershed management

•landscape and aesthetics

The Commiphora tree is the host plant of this beetle. When the beetle's larvae feed on the leaves, they produce a toxin (not found in the adult beetle) which is extremely toxic. Kalahari Desert Bushmen squeeze to fluid onto their arrows to bring down adult antelope.

However, timber loss, and more importantly, the disruption of long-term forest management plans, are major concerns to forest managers and planners.

Additional Pictures

Greensmiths is excited to introduce a new friend to our web site visitors. Mr. Mike Ash is a photographer from Tampa, FL and he is sharing many of his personal favorite pictures for our web site. He wishes to share his pictures with our many visitors for their personal use only. We encourage Students, Teachers and Professionals to feel free to use these pictures for training and learning purposes.

None of his pictures may be used on any other website or for sale or profits without the written permission of both Mr. Mike Ash and Greensmiths, Inc. We wish to thanks Mike for his hard work and these wonderful images and we hope you enjoy them as much as we do

Milkweed Tortoise Beetle