Insects Steal the Show at Riverside Sycamore Canyon Wilderness Park BioBlitz!

November 17, 2015

Riverside Citizen Science BioBlitz participants heading into the field. On October 17, scientists and volunteers brought their equipment, expertise, and enthusiasm for biodiversity to Riverside Citizen Science’s first-ever BioBlitz. Starting at dawn and “nature-partying” into the night, Riverside residents explored Sycamore Canyon Wilderness Park in search of floral and faunal diversity. There are a variety of reasons why the intense sampling of plants and animals that defines a BioBlitz is important: to foster a community committed to environmental stewardship, to unite amateur and professional scientists to learn from one another, to document the astounding diversity of life that exists – even in urban environments – and, importantly, to provide baseline biological monitoring that can facilitate future management.  Sycamore Canyon is a case in point. The 1,500-acre park is of special interest to the Riverside County Habitat Conservation Agency because it is home to the endangered Stephens’ Kangaroo Rat (Dipodomys stephensi). The Stephens' kangaroo rat is threatened by non-native, invasive grasses that can grow so thick that the rat cannot forage for seeds easily. To provide home improvement for the rat, Sycamore Canyon park managers have used sheep grazing in recent years to control the density of invasive plant species.  Riverside Citizen Science BioBlitz participants helped uncover some of the secondary impacts of the grazing: grazed and ungrazed areas differ in their insect diversity.

An unexpected bonus: UCR entomologists found a decaying log with a termite colony in it. Everybody got to take turns collecting termites. In the study of insect diversity, entomologists have developed a variety of methods to capture insects and measure the number of unique types (or “richness”) of insects. One easy way to capture flying insects is with pan traps. Pan traps are simply bowls of soapy water, where the soap is added to minimize surface tension, trapping even the smallest insects. The color of the bowls is important: Entomologists around the world have found that yellow and blue bowls attract the most insects, with some types of insects more attracted to a particular color. Soapy water is poured over filter paper to remove the insects. Insects caught in the filter paper are brought back to the lab and identified.  At the Riverside Citizen Science BioBlitz, UC Riverside entomologists led groups of citizen scientists in deploying and collecting pan traps in grazed and ungrazed areas of habitat. The UC Riverside Entomology Museum’s senior scientist, Dr. Doug Yanega, identified the collected insects under a microscope. Identifying all the species of insects in a new location is typically not possible; instead experts try to identify the insects to the lowest possible taxonomic level (or “taxa”, for short). Really good taxonomists, like Doug, hope to classify insects to family. (This is akin to identifying a mammal – in the class Mammalia – to the family “Felidae”, or cats.) 

UCR entomologists and citizen scientists collecting insects from pan traps. The next step was to count the number of distinct taxa in blue and yellow pan traps in grazed and ungrazed locations. While similar kinds of insects were found in grazed and ungrazed locations, greater richness was found in the ungrazed areas. We did not find a difference in diversity between blue and yellow traps, the two trap colors were similarly effective in measuring insect diversity at this BioBlitz. However, we did catch more aphids (family Aphididae), white flies (family Aleyrodidae), honey bees (species Apis mellifera), and hover flies (species Eupeodes volucris) in the yellow pan traps than in blue pan traps. 

Ungrazed habitats support greater insect diversity. Pan traps in ungrazed habitats captured more unique kinds of insect taxa (greater richness) than pan traps in grazed habitats. The pan trap color (represented by the color of the bar) did not influence the diversity of insects captured, both yellow and blue pan traps were effective in measuring insect diversity.    We hypothesize that the difference in insect diversity is related to vegetation differences. Overall, we saw more plants than expected due to early rain that occurred two days before the Riverside BioBlitz. Normally, vegetation is dead or dormant in October in Riverside, after the hot, dry summer. Of the 50 plant species we recorded, some natives were even blooming: California buckwheat (Eriogonum fasciculatum), California sagebrush (Artemisia californica), black sage (Salvia mellifera), and fiddleneck (Amsinckia menziesii). However, the rain also helped invasives, where there appeared to be more invasives and higher overall vegetation cover in ungrazed areas compared to grazed areas. This highlights a big challenge in managing natural parks: a particular action (reducing invasive plants by sheep grazing) may have winners (the Stephens’ kangaroo rat) and losers (insects).  Insect sampling continued into the night with a special night-time collection method. We set up a light trap (a mercury vapor lamp in front of a white sheet) to attract night-flying insects. The light trap mimics moonlight to attract insects that use the light of the moon and stars to aid in navigation. 

UCR entomologists and citizen scientists collecting insects at night under a mercury vapor lamp. It was during our nighttime insect sampling that we got our biggest surprise.  We found a beetle, Pharaxonotha kirschii, from Texas that has never been seen in California before. Unfortunately, the beetle is a pest. We reported it to the USDA in the hopes that discovering it early will keep it from becoming a pest in California. These types of surprises are one of the reasons BioBlitzes are so useful (and thrilling).  Although the insect results are exciting, Riverside Citizen Science BioBlitz participants recorded other wildlife also. Citizen scientists led by local ornithologists recorded 22 year-round resident bird species. The hot day frustrated their hopes for a more extensive species list. We observed many individual lizards, represented by just four species: granite spiny lizard (Sceloporus orcutti), side-blotched lizard (Uta stansburiana), western fence lizard (Sceloporus occidentalis), and orange-throated whiptail (Aspidoscelis hyperythra). Although we only saw a couple mammal species – squirrels and rabbits – we measured burrow sizes to better understand what kind of small mammals (such as Stephens’ kangaroo rats) live in the park. Thanks to their scat, we also know coyote are in Sycamore Canyon Wilderness Park. At night, led by a bat biologist, Riverside Citizen Scientists used night vision goggles and sonic recorders to observe a number of California myotis bats (Myotis californicus).  While the insects stole the show in terms of overall diversity, the real stars at the first-ever Riverside Citizen Science BioBlitz were the citizen scientists who did the exploring, searching, collecting, counting. A BioBlitz is an intense and frenzied event that depends on the enthusiasm of many participants. We were blown away by the fantastic turnout and the eager curiosity on display throughout the whole day!


(Posted by: Erin Conlisk and Sarah O'Neill)

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