MFWB_A - Insects and Us

angiosperms

flowering plant, caused an increase in the expansion of insect biodiversity when it evolved

must have’s for pests

correct habitat (close to ecosystem of plant), produce many young (depends on how early they mature, times of reproduction in a year (many times is more damage)), life cycle fit around harvest

pests species

9000, 5% are serious to humans, cocoa has 1400, cotton has 1360, sugarcane has 1300, the plant only needs to be infected with 4-8 species

loss per annum in natural systems

10%

climat change and crop damage

31 phytophagous pests - 41% expected to lead to increased pest damage, 4% to reduce and 55% mixed

migratory/desert locust

migrate when high rainfall, migratory form - longer wings, sexually underdeveloped (lighter when flying), undergo physical change to gregarious form, only swarm when there’s a combo of atmosphere and food shortages, 3-400 eggs over 5/6 month lifespan, 2g of vegetation a day

defence against insects

chemical insecticides by packs or air, spraying (harmful to human health), drones can apply pesticides, electrified grid

tobacco whitefly disease transmitted

bemisia tabaci, only one needed to destroy whole crop

BT

500+ host plants, direct damage - chlorosis, decreased yield, ~5% of net primary production, stylet-borne viruses that are transmitted between hosts, many can carry but not transmit

tomato yellow leaf curl

BT only species that transmits it, can be fatal - circulative virus, may or may not reproduce, 24 morphologically indistinguishable types, infected TYLC tomatoes more attractive to B and Q BT types, females of Q are better feeders and transmitters than the rest

stored product pests

adapted to high temperature, low humidity, e.g., tenebrinoids (mealworms) absorb water from air, mediterranean flour moth develop where the water content is 1%

future pest control plans

plant breeding for insect resistance, BT cotton and maize - single gene resistant, polygenic/horizontal resistance, currently bred for yield not defence, plants communicate with odours - bring them back, attract pest-eating predators

pollination

87% of plants rely on animals for pollination, some can self-fertilise but pollination brings better yield, fruit/seed production, provide enhanced genetic vigour, 87/115 of most important crops require insects

bee pollination

attracted to blue and yellow colours, hairs pick up pollen, pollinate 1/3 of human food

non-bee pollination

25-50% of flowers, less effective than bees but more visits, fruit sets increase, not as reliant as bees on natural surroundings,

fly pollination

arctic, alpine regions, no nest so less energy/nectar needed, for difficult or small pollination, 555+ plant species, little pollen/nectar reward

moth pollination

pale, sweet scented, nocturnal and long corolla, yucca moths - lies eggs in flowers, caterpillars hatch and eat on them m

moth pollination threats

streetlights affect development, reproduction, escape from predators, pollination, exhaust fumes can smell similar to floral hosts, harder to distinguish local and target species

beetle pollination

annually pollinate 88% of flowering plants, highly fragrant, open, dish shaped flower, sacrificial parts (ovules) tucked away as beetles are clumsy, hairy undersides

threats to pollinators

land-use intensification, pesticides, climate change, disease, toxic alien species, limited immune systems