Biology of Insects and Pollination

Vallisnaria is the genus of aquatic plant. In this plant, pollination is done by pollinating agent i.e., water. Female flowers have long stalk and appears on the surface of the water. When the male flower releases pollen grain it reaches to the stigma of female flower through water current.

Corss pollination is when pollen from one plant pollinates flowers on a different plant. With maize, cross-pollination is preferred because it is a monoecious crop with male and female flowers in separate parts of the same plant. So, male part produces a large number of pollen grains, which are then distributed by wind to other female parts of another maize plants.
Thus, the correct answer is option (D), 'Cross pollinated by wind'.

The most recognized pollinators are the various species of bees, which are plainly adapted to pollination. Bees typically are fuzzy and carry an electrostatic charge. Both featured help pollen grains adhere to their bodies, but they also have specialized pollen carrying structures; in most bees , this takes the form of a structure known as the scopa, which is on the hind legs of most bees, and the lower abdomen, made up of thick, plumose setae, honey bees, bumble bees and their relatives do not have a scopa, but the hind leg is modified into a structure called as corbicula. Most bees gather nectar, a concentrated energy source and pollen, which is high protein food, to nurture their young and inadvertently transfer some among the flowers as they are working.

Insect-pollinated flowers usually possess sticky and heavy pollens with a rough surface that allow them to stick to insects easily. Flowers also have sweet nectar that attracts insects that go from flower to flower to pollinate the flowers. The pollen grains are also in small quantities, because it is very likely that insects will enter another flower, and the pollen grains would have a higher chance of landing on the stigma. That's why there is no need of pollen grains in large quantities. 

• Pollination is the transfer of pollen from the male anther to the female stigma. It is carried out with the help of animals, birds, insects, water, wind, etc. 
• The pollination carried out by insects is called entomophily. 
• Pollination carried out by water is called hydrophily. Pollination carried out by the wind is called anemophily.
•  Pollination carried out by the animals is called zoophily. 

• The pollination mechanism in Salvia is a unique lever type. The flowers in this genus are arranged in thyrsus inflorescence and they are attractive and well adapted for cross-pollination through the agency of insects. 
• In this lever mechanism of pollination, the Corolla has a spreading upper lip, which acts as a landing place for the insect. When the insects land on the lower lip of the corolla and in its endeavor to obtain nectar that is secreted by the hypogynous disc, pushes the sterile lobes of the stamen inwards.
•  Due to this the upper half of the connective with the fertile lobes acts as a lever. Then the anther lobe comes down and shed the pollen on the back of the insect.

• Blastophaga quadriceps, the legitimate pollinator of Ficus religiosa, possesses two thoracic pockets in which pollen is stored for subsequent introduction into the young figs.  
• Pocket loading takes place in the nearly ripe fig at the male phase. Impregnated female wasps leave the fig via narrow channels bored by the males. 
• Upon entering young receptive figs, the female wasps begin oviposition, during which pocket emptying and pollination takes place.

Pollination through insect is called as entamophily in which insect is attracted by nectar secreted by flower and colorful petals.

Many flowers produce nectar. When an insect lands on a flower to feed, pollen grains stick to its body. As the insect moves to another flower of the same species, these pollen grains are transferred to the flower’s stigma and pollination occurs.

Anemophily is a type of pollination in which pollination takes place with the help of wind. Entomophily is a type of pollination in which pollination takes place through insect. Myrmecophily is a mutual association of some plants with ants to save themselves from other animals. Hydrophily is a type of pollination in which pollination occurs through flow of water. 

The Yucca moth is also termed as the Pronuba moth. It is a small white moth that lives in the semi-arid habitats where Yucca plants grow. The Yucca moth is well-known for its relationship with the Yucca plant. The Yucca moth’s larvae are relying on the seeds of the Yucca plant as a primary food source. No one can exist without the other, creating an obligate mutualism between the moth and the plant. It is true for types of Yucca moths such as Tegeticula .

 So correct answer is option B.