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Questions

1. Above what daily maximum temperature do significant amounts of barber’s pole worm eggs develop to infective larvae if moisture is not limiting?

2. Early season flystrike prevention relies on what strategy to reduce flystrike?

3. What is the most likely cause of a failed attempt to eradicate lice?


Cold conditions will prevent barber's pole worm eggs from developing to infective larvae.
Cold conditions will prevent barber's pole worm eggs from developing to infective larvae.

Answers

1. Above what daily maximum temperature do significant amounts of barber’s pole worm eggs develop to infective larvae if moisture is not limiting?

When maximum daily temperatures exceed 18°C for about 5 days, and dung pellets have become wet with about 10–15 m rain over the same time (or the ground is waterlogged), then significant numbers of barber’s pole worm eggs will hatch and develop to infective larvae on pasture. In colder areas, scour worms can be developing at much lower temperatures.

2. Early season flystrike prevention relies on what strategy to reduce flystrike?

Early season flystrike prevention suppresses the normal build up of a fly population in spring, so that there is a lack of flies to strike sheep. It involves applying a long-acting flystrike preventative to the whole flock before any fly activity in spring, followed where possible, with shearing or crutching when the chemical protection period is ending. The aim is to have so few flies later in the season that the risk of strike is greatly reduced.

3. What is the most likely cause of a failed attempt to eradicate lice?

Although resistance often gets blamed for lice control breakdowns, the majority of breakdowns result from under-dosing, poor application, sheep missing treatment or reinfestation; not resistance. When a treatment failure occurs, it is essential to carefully review your application method, ensure that all sheep were treated and to check that new lousy sheep have not entered the property before deciding that resistance is the problem.

Resistance, is however, widespread to the synthetic pyrethroids (SP), some resistance to Insect Growth Regulators (IGR) is known, and just one strain of lice with reduced susceptibility to organophosphates (OP) has been reported, but OP resistance is thought to be rare.