Internet News Page

BioPol Internet Newsletter

Subjects:
New Bumblebee Box
Bemisia control in sweet pepper
Anthocoris nemoralis

New accommodations for BioPol bumblebees

Since 1995, BioPol has marketed the well-known white-green bumblebee box; virtually entirely made out of cardboard. Prior to this, the bumblebees were delivered in wooden boxes. However, the bumblebees have now found their third new home in a new type of bumblebee box.

Photograph: New Bumblebee Box

The main difference compared with the ‘old’ bumblebee box is the hive (the inner box) itself, since the hive is made entirely of plastic. Particularly the increased sales of colonies was what prompted us to develop the new box. With a view to the production process, the new box yields significant savings in labour.

Obviously, the new box should at least meet the same quality requirements, preferably adding additional benefits.

Critical assessment was therefore conducted to signal every opportunity for improvement. Particularly the bumblebee droppings in the hive presented concerns with respect to contamination. Although there is no evidence to suggest that droppings in the hive are harmful to the development of bumblebees, it seemed that this area presented an opportunity for improvement.

The new hive was therefore designed to incorporate grooves around the hive floor. This keeps the colony clean, so that they enter the casing (the outside box) in a clean state.

Furthermore, it may occur – especially in summery conditions – that the temperature in the colony rises to less desirable levels. Particularly in export countries in the Mediterranean. In order to prevent this in the future, the box was designed with a larger number of ventilation holes all around, while white was again selected as the key colour, as it reflects more light. It is important, however, to ensure that the colonies are exposed to as little draught as possible.

The openings in the box that the bees can use to fly in and out were changed as well. A small plastic slide valve on the side of the box serves to close these openings. If you slide it to the right, the bumblebees can fly in and out. Whenever you want to ‘collect’ the bumblebees, you can slide the valve to the left to ensure that the bumblebees can enter, but cannot leave the box. The former version had fly-in and fly-out openings in front of the colony. As the valve is now placed at the side of the colony, this allows for larger numbers of colonies to be placed side by side on the tube in the greenhouse.

The dimensions and the appearance of the box were equally subjected to change; the box is now wider and less tall, resulting in logistic advantages. And finally, the new, brightly coloured design adds new appeal to the box.

Back to subjects

Bemisia has significant impact on integrated pest control system in sweet pepper cultivation

In the past year, many sweet pepper producers were confronted with serious concerns due to whitefly. In many instances people were unable to make the timely observation that it was the tobacco whitefly, rather than the greenhouse whitefly that was the culprit. Tobacco whitefly (Bemisia tabaci) cannot be adequately controlled using Encarsia formosa and Eretmocerus eremicus. Even chemical correction using Admiral failed to produce the desired effect. The use of wide-range remedies was therefore unavoidable in most cases. Subsequently, people were often compelled to abandon the entire biological system.

For the season of 2001 it is strongly recommendable to pursue a different strategy. Part of the solution may be found in the distribution of the predatory bug known as Macrolophus caliginosus. However, this method would have rather dramatic consequences for the overall control plan. Macrolophus is highly sensitive to Pirimor; a spacial treatment using this method would virtually extinguish the entire population. Full-field (chemical) control of the glasshouse and potato aphid would then become a real problem.

In addition to Macrolophus, BioPol presents a special product for the control of Bemisia. This product is called 'Bemisiamix' and consists of chrysalides of Encarsia formosa and chrysalides of Eretmocerus mundes. The Encarsia that are used in the mix were bred on tobacco whitefly for this specific purpose. As they emerge, the parasitic wasps are then already accustomed to Bemisia and will prefer them to greenhouse whitefly. Eretmocerus mundes is usually quite ready to deal with Bemisia. The use of Bemisiamix is especially advisable when Bemisia has already been detected. It is important to define a good strategy in advance in order to be able to control the rest of the pests in a biological or integrated manner as well.

As Macrolophus is a polyphagous insect, this bug will accept – in addition to whitefly – various insects as a source of nutrition. Apart from whitefly, Macrolophus will also feed on (red) spider mites. And also caterpillar eggs, small caterpillars, aphids and, to a lesser extent, thrips are listed on the menu of this predatory bug. If there are no insects available in the greenhouse, Macrolophus can even live on sap. The population build-up will develop more slowly on vegetable sources of nutrition.

In order to ensure that Macrolophus has a chance to succeed in sweet pepper cultivation, the control of the potato aphid will probably require a different approach as well. If Pirimor is used as the sole weapon in the control of this aphid, the population development of Macrolophus would be restrained too strongly. However, glasshouse and potato aphid in sweet pepper cultivation causes rather substantial damage even in small populations. Preventive distribution of the parasitic wasp Aphidius ervi as basic control measure is therefore recommendable. In addition, however, it is important to apply other aphid control measures as well. Particular examples that come to mind in this respect are predators such as Hippodamia, Harmonia and lacewing larvae. The strategy behind this is the notion that in spite of a properly functioning ervi system, there is still a very real risk of substantial damage. This is so because after ervi parasitizing, the potato aphid remains alive for a few more days before mummification sets in. So even though the aphid is eliminated after parasitizing, it still has a chance to cause damage. Using predators such as the ones mentioned above, there is no mummification and the aphid is eliminated immediately. If potato aphids are found in your crops, Hippodamia will make a clean sweep. Hippodamia is supplied in cups containing 5,000 adults and is a relatively inexpensive means of pest control. The disadvantage is that Hippodamia is not available throughout the year. Harmonia and lacewing larvae are available in all seasons. Contrary to Hippodamia, these control agents are wingless and are therefore likely to stay longer in the place of distribution. A system using only Harmonia and lacewing will prove to be more expensive, though.

Finally, an open culture of cereal aphid (Aphidius colemani) on tussocks of corn can be used in support of a high population build-up of ervi. For a fully biological approach one cannot help but tolerate some harm, to a certain extent.

Back to subjects

Pear psylla control using Anthocoris nemoralis

In pear cultivation, pear psylla forms a serious threat to the producer. Chemical agents are hard to come by, and fail to yield the desired results. In the past year, tests have been conducted under Dutch conditions, involving the use of assassin bugs. The results of these tests showed that Anthocoris nemoralis yields highly beneficial effects in the control of pear psylla. The results obtained in Italy and Belgium showed similar effects. For this reason, Dutch producers use Anthocoris on a broad scale throughout the Netherlands in 2001. For further details, click HERE.

Back to subjects

Back to homepage