Cold-blooded mosquitoes love the heat
Mosquitoes are cold-blooded and therefore love hot weather, says UC Davis research entomologist and professor William Reisen of the Center for Vectorborne Diseases. Hot weather speeds up their metabolism, so they feed on blood and lay their eggs more frequently. Bottom line: hotter weather increases the odds for female mosquitoes to become infected with the West Nile virus (WNV) and to transmit it the next time they bite.  Culex mosquitoes, the principal carriers of WNV, are most active around sunset, Reisen says. Culex tarsalis feed near sunset, whereas Culex pipiens usually feed two to three hours after sunset. “You can avoid mosquitoes during those times by going into your air-conditioned home, turning on the TV and drinking a cold beer,” he quipped.  “If you don’t have to be outside after sunset when the mosquitoes are biting, don’t.  If you do, cover up by wearing a long-sleeved shirt and long pants, and spray any exposed skin with DEET.” Particularly at high-risk after sunset are smokers, who often are relegated outdoors to smoke. For more information, contact Reisen at (530) 752-0124 or arbo123@pacbell.net. Tip by Kathy Keatley Garvey (530) 754-6894, kegarvey@ucdavis.edu.

Warm weather favors bacteria growth on fresh melon
Fresh, ripe melons are a summertime favorite, but they require special attention to keep them safe in hot weather. Unlike most fruit, melons are not acidic. Bacteria can multiply rapidly on the flesh of cut melon that is not kept cold. Cantaloupe -- an excellent fruit choice because of its low calorie count and high levels of beta-carotene, potassium and Vitamin C -- in particular requires judicious care. Compared to the smooth, waxy rind of melons like honeydew and watermelon, cantaloupe’s rough, netted surface makes it more difficult to remove field soil, where bacteria are most likely to be found. Laboratory studies have shown that passing a knife through a cantaloupe with Salmonella on the surface, not surprisingly, contaminates the edible flesh. The flesh is an excellent “growing ground” for the microbes. Nevertheless, UC experts discourage the use of soaps or household bleach on melons and other fruits. The substances may be absorbed by porous surfaces or transferred to the flesh during peeling and cutting. The best defense against melon-borne illness is rinsing the melon under running water and brushing the rind with a clean vegetable brush to remove dirt. Then, keep the cut fruit refrigerated until it is eaten. Throw away cut melon that has been kept for longer than two hours at room temperature or one hour at temperatures over 90ºF. A free five-page publication on cantaloupe safety is available at http://anrcatalog.ucdavis.edu/pdf/8095.pdf. Tip by Jeannette Warnert, (559) 241-7514, jwarnert@ucop.edu.

Protect farm animals from heat stress when transporting them to fairs 
Youth, including 4-H members, who transport their livestock to county fairs in hot weather must be vigilant about heat stress, says veteran 4-H leader Sandy Bonesteel of Dixon. A short trip from the barnyard to the fair, especially during high temperatures and humidity, can severely stress an animal. She recommends:

• adding a layer of wet sand to the trailer bed to prevent overheating (wet sand also improves animal footing, whereas hay is more slippery and holds in the heat)
• watering down the steer, hog, goat or lamb before loading it on the trailer
• leaving early to avoid the heat (10 a.m. is too late)
• having spray bottles and water containers ready when the animal is unloaded

During the fair, make sure the barn is well ventilated and the animals have plenty of water. “Ideally, the roof of the livestock barn at the fair should be painted white. Black holds in the heat,” Bonesteel said.  Exhibitors should also expect their animals to lose weight during the transport. Hogs can lose 10 pounds in a trip as short as 10 to 15 miles, she said. “Hogs are more susceptible to heat stress than any other farm animal because they don’t sweat, they pant.” It’s not uncommon for a steer transported 25 to 30 miles to drop 40 pounds. Bonesteel, who as a 4-H’er showed dairy cattle for nine years at county fairs, is an 18-year 4-H leader of the Maine Prairie 4-H Club, Dixon. 4-H is part of UC Cooperative Extension. For more information, contact Bonesteel at (707) 678-5014. Tip by Kathy Keatley Garvey (530) 754-6894, kegarvey@ucdavis.edu.

Don’t give your child a tummyache
Warmer weather and outdoor activities make food-borne illnesses more prevalent in the summer. Children are especially susceptible, according to Shirley Peterson, the UC Cooperative Extension nutrition, family and consumer sciences advisor for San Luis Obispo County. “Children are smaller than adults, so the same amount of contaminated food would be more likely to make a child sick,” Peterson said. “Also, children don’t have as much stomach acid, the body’s first defense against food-borne bacteria, and their immune systems are not fully functioning till age 6.” For these reasons, it is especially important to take precautions that keep children’s food safe in warm weather. Peterson and her colleagues developed a training CD titled “Don’t give your child a tummyache” that teaches parents and other child care providers food safety basics. Viewers learn to wash hands before and after touching food or eating, and to keep the temperature of food out of the “danger zone” – between 40ºF and 140ºF, the temperature at which bacteria multiply very rapidly. Peterson recommends caregivers be particularly cautious with foods that are protein-rich, such as meat, eggs and dairy products. “Food that is moist and high in protein content is ideal for rapid bacteria reproduction,” she said. For more information, contact Peterson at (805) 781-5951 or sspeterson@co.slo.ca.us. The CD-ROM “Don’t give your child a tummyache” may be purchased for $20 at  http://anrcatalog.ucdavis.edu/InOrder/Shop/ItemDetails.asp?ItemNo=21586. Tip by Jeannette Warnert, (559) 241-7514, jwarnert@ucop.edu.

Summertime more stressful for California cows
Maintaining milk production is more difficult in the summer, when rising temperatures trigger cows to eat less, knocking production down 10 to 15 percent, according to UC Cooperative Extension dairy farm advisor Jerry Higginbotham. That’s a great concern for dairy operators, whose industry in 2005 accounted for $5.37 billion of milk and cream, California’s No. 1 agricultural commodity. Over the years, dairy operators have worked with UC scientists to develop ways of cooling cows, keeping them more comfortable and productive through hot summer months. “Wetting them with misters and blowing air on them to evaporate the moisture cools off cows just as when people take a dip in the swimming pool and get chilled by a summer breeze,” Higginbotham said. Temperatures over 100 degrees are common in the parts of California where most dairies are located – the San Joaquin Valley, the Coachella Valley and the Sacramento Valley. At 85 degrees, the cows already begin to experience the effects of heat stress. When temperatures approach 100, “cows will be panting with their tongues hanging out of their mouths,” Higginbotham said. “Just like humans, they’re uncomfortable when it’s hot outside.” For more information, contact Jerry Higginbotham, (559) 456-7558, or gehigginbotham@ucdavis.edu. Tip by Jeannette Warnert, (559) 241-07514, jwarnert@ucop.edu.

UC offers free heat stress training information to agricultural employers
UC Cooperative Extension specialist Howard Rosenberg is helping agricultural employers meet the challenges of heat stress by providing information for them to share with their workers. “Many workers are inundated with signs, slogans and exhortations. I came to the conclusion early on that most pitches about drinking water were falling on deaf ears, because they were short on ‘the why.’” said Rosenberg, who is based at UC Berkeley. “Some employers might say, ‘Do it or you’re fired,’ others might implore, ‘Do it because I’m asking you to.’ I say, do it because it makes sense. I encourage growers and supervisors to tell workers, ‘Here’s what happens, here’s how your body works, you decide.’” To help employers train workers, Rosenberg has produced 200,000 copies of pocket-sized fold-out cards -- in Spanish on one side, English on the other -- with key points for outdoor workers on avoiding heat stress. The cards are being offered in partnership with the California Farm Bureau Federation and with support from the USDA Western Center for Risk Management Education. Farm Bureau is distributing free supplies of cards to agricultural employers statewide. To order copies, contact Danielle Rau at drau@cfbf.com, (800) 698-3276, Ext. 5596. Rosenberg has also put a vast collection of practical material on heat stress online at his Agricultural Personnel Management Program Web site, http://apmp.berkeley.edu. Information on complying with the new laws protecting outdoor workers, training aids, a pdf version of the field education card, articles and heat stress references are all available free of charge. For more information, contact Rosenberg at (510) 642-7103, howardr@are.berkeley.edu. Tip by Jeannette Warnert, (559) 241-7514, jwarnert@ucop.edu.