Bagrada Bug & Winter Veggies!
Now that we are planting winter plants, this creature is one to pay attention to because those are its favorites! Infestations have already occurred in Pilgrim Terrace Community Garden on broccoli and kale. The population explodes, overwhelming the entire plant. The word infestation takes on true meaning here.
Small black bugs with orange and white spots. Bagrada bug is a major pest of crop plants such as cabbage, kale, turnip, cauliflower, mustard, broccoli and radish. In the U.S., harlequin bug is used as a common name for another species of shield bug, Murgantia histrionica. It was first found in Los Angeles County in June 2008 and has spread widely in other Southern California regions since then. It is not known to bite humans or carry any sort of disease.
Bagrada will also go after warm-weather crops such as papaya, potato, corn and beans, but is more lethargic in heat. It spends its time in the soil, laying eggs or hiding; heavy rains drive it out of air pockets and onto the plant du jour. It prefers to eat seeds and succulent plants, so when local climates dry and reduce available food such as wild mustard in Southern California’s canyons, into town it comes.
Adults and nymphs suck juices from the plant. Feeding results in large stippled or wilted areas on leaves, white edges being one of the first signs. Often the growth of newly formed central shoots or heads of plants become stunted. The pest can stunt growth and kill plants.
Populations can build up quickly reaching damaging densities that require control. Heaviest infestations are typically observed at organic farms, community gardens, and residential vegetable gardens where little or no pesticides are used. Gardeners often think they have beneficial lady bugs, because Bagrada adults and larger nymphs are about same the size and coloration as ladybugs. They are good at disguise. It also has a potent aroma. “Once you smell it, you will never forget it,” said Gevork Arakelian, senior biologist at the Los Angeles County Department of Agricultural Commissioner/Weights and Measures. “It’s very specific for stinkbugs, a pungent, intense, parsley odor. Birds don’t touch them. If they eat one, they disgorge it immediately.”
Usually all life stages are present together on plants and adults are commonly observed in copulation. Since Bagradas lay most eggs in the soil, natural predators such as wasps aren’t effective controls. It is often not feasible to pick off by hand because the infestations are so thick and sudden. If you try it, it takes two hands. They see you coming, move fast, drop to the ground never to be found! Put one hand underneath and close it fast when they drop. If you step on them, be sure the squish factor has happened, because they are smallish, and just sink in rather than squish, get up and walk away to tell the story. Sorry, just trying to give you the idea what you are up against. Normal pesticides can be used to ward off a Bagrada bug infestation, but insecticides aren’t an option for many gardeners, and adult bugs will simply flee one garden for another, only to return when the residue of pesticide is gone.
–> If you garden in a community garden, tell everyone about this pest, ask your neighbor gardeners to keep a close watch after heavy watering or rains. <– I’m checking each of my susceptible plants daily and have found some of the bugs, which I immediately sent to Heaven. I don’t know if they were already at the garden, or came in with the transplants. Check for eggs on the undersides of leaves of transplants you purchase.
What you can do! From infonet-biovision, Nairobi, Kenya – they oughta know since this little pup hails from Africa!
Monitoring– Regular monitoring of the crop is important to detect bagrada bugs before they cause damage to the crop.
Sanitation – Crop hygiene, in particular removal of old crops and destruction of weeds of the family Cruciferae prevents population build-up.
Hand picking – Handpicking and destruction of the bugs helps to reduce damage. This is particularly important in the early stages of the crop. Hand picking is only practical in small plots.
Cultivation – Eggs laid in the soil are readily killed by cultivation, so frequent light cultivation (once or twice a week) of the vegetable beds will help in controlling this pest (Keizer and Zuurbier; Horticultural Research Program, Botswana).
Irrigation – Watering and overhead irrigation disturb the bugs discouraging them from feeding on the crop. However, note that use of sprinkler irrigation may lead to increase of diseases such as black rot and downy mildew.
Mixed cropping – Growing strong smelling plants such as garlic, onion or parsley near the crop are reported to reduce infestations (Dobson et al, 2002).
Biological pest control
Natural enemies – Eggs of bagrada bugs are parasitized by tiny wasps. Bugs are parasitized by flies (e.g. Alphorn sp.).
Biopesticides and physical methods
Plant extracts – A mixture of chili, soap, garlic and paraffin has shown to be an effective control method in trials in Namibia (Keizer and Zuurbier).
Natural products – In Namibia there are reports that sprinkling the plants with crushed bagrada bugs repels other bugs. This can be used effectively in combination with frequent soil cultivation (Keizer and Zuurbier).
Soap solution – Spraying plants with a soapy solution (bar soap) has been found effective against bagrada bugs. It helps to wash off young bugs (Dobson et al, 2002; Elwell and Maas, 1995).
There you have it! Due diligence, and if you believe in it, prayer!
9.28.12 see UPDATE!