B.tabaci Talk

Question 1

First slide - description

Answer 1

State they are Hemipteran
Small in size 0.8mm
Holometabolous
As with other Hemipterans they have piercing and sucking mouthparts designed to feed off plants

Question 2

Second slide - life cycle

Answer 2

Egg stage - pyriform shape, anchored to epidermis, 0.2mm, greeny-yellow colour but darken over time
Larval Stage - Known as crawlers, 4 instars, eyes redden prior to pupation
Adult stage - Prior to pupation takes anywhere from 24-120h before first eggs are laid, can lay 10 eggs per day living as an adult for 15-20 days = 150-200 eggs

Question 3

Third and Fourth Slides - location

Answer 3

As can be seen on the map B.tabaci has been found, to some extent, on every continent except Antarctica
Widespread in Holland, Saudi Arabia/Yemen and Mauritius
Present heavily across the equator
Thought to have originated in India
UK no sightings

Question 4

Seventh Slide - plants

Answer 4

Found to be a pest species in over 40 different species of plant
Cotton, soybean tobacco and leguminous plants
Can be detrimental to all growth stages due to the multiple ways whiteflys affect plants

Question 5

Eighth Slide - Problem

Answer 5

Like other Hemipterans it feeds off the host plant by piercing phloem and removing nutrients
Also produce honeydew
Vector of plant diseases such as tomato yellow leaf curl, African cassava mosaic, Lettuce infectious yellow and cassava brown streak viruses

Question 6

Ninth Slide - resistance

Answer 6

Whiteflys were the first reported insect to show resistance to imidacloprid in 1996
Done this through an overexpression of the P-450 monooxygenases involved in detoxification
Due to this method there has been evidence of detoxification in other insecticides both neonicotionoids and others
Due to the similarities in structure (point out imidacloprid and pymetrozine structures)

Question 7

Tenth Slide - Oils

Answer 7

Most effective oil on the market is the ultra-fine oil
Been shown to reduce settlement of adult flies, decreases ovipostion and abates the transmission of the tomato yellow leaf curl virus
These oils can cause direct mortality to all immature life stages
Sugar apple oil shown to be as effective as insecticides
Causes nymph to shrink and detach from the plant resulting in starvation
Growth hormone regulators - Causes malformations of chitin in juveniles leading to death, doesn’t affect adults but can sterilise the eggs of the treated adult, safe to vertebrates and bumblebees

Question 8

Eleventh Slide - Biocontrol

Answer 8

Eretmocerus spp. - parasitic wasp
- primary, bi-parental, solitary, ecto-endoparasitoid of whiteflys
- part of development spent feeding on outside of the host before development completed inside
Coleoptera - D.pusillus predates upon all stages of the whitefly both as an adult and during larval stages by piercing the integument of the insect and extracting the contents
- Tends to avoid parasatised whitefly and so is good in conjunction
Lacewings - 10 species of lacewings reported to feed on whitefly nymphs
- larval form of lacewings feed on the immature stages of the pest
Fungal - Beauveria bassiana shown to be the most effective fungal treatment of whiteflies

Question 9

Twelfth slide - Cultural

Answer 9

Planting different crops away from each other
Good sanitation
Removal of weeds and host crop residues immediately to prevent carry over

Question 10

Thirteenth Slide - Mechanical

Answer 10

LED trap - simple, cheap, effective
- Works best at night
- durable
- whitefly parasite friendly
Floating Row - Covers the plants and thus reduces exposure
Trap crops - squash crops for example, border the field with preferential crops that whiteflys prefer to reduce the exposure of cash crops to pest