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Sacramento, CA, United States

Dowell R.V.,1681 Pebblewood Drive | Wood T.K.,University of Delaware
Pan-Pacific Entomologist | Year: 2014

The goals of this study were to 1) determine the field survival rate of single and multiple U. crassicornis females tending their offspring, 2) determine if a female will adopt an egg mass or nyphal aggregation that has lost its parental female as is seen in other treehoppers, 3)determine the physical characteristics of the sites selected by female U. crassicornis for oviposition and 4) show how these data interrelate and explain the pattern of U. crassicornis egg mass deposition within and among the host plants. An average of 27.9% of the female U. crassicornis survived until their offspring reached maturity. Having two or more females at a site doubles the probability of at least one surviving until the offspring reach maturity. An egg mass or nymphal aggregation without a guarding female may be adopted by another female. Females need four to seven cm of plant tissue 2.5 to 3.5 mm in diameter that they can encircle with their mesothoracic legs in which to oviposit. The females do not aggregate their egg masses but rather randomly distributed them among sites with the proper physical characteristics. The random distribution of egg masses provides a bridge between maximizing offspring survival and fecundity of the daughters. Source


Dowell R.V.,1681 Pebblewood Drive | Wood T.K.,University of Delaware
Florida Entomologist | Year: 2014

Umbonia crassicornis mortality in single cold temperature exposures increased with decreasing temperature, and the equation, Y = 8.43X + 1.758X 2 + 4.295, describes the relationship between mortality (Y) and cold temperature (X). Multiple exposures to freezing temperatures increased mortality by 1.7 to 12.3 fold. Periods of freezing temperature occur every other year at the insect's northern limit of its range in Florida and are one factor responsible for limiting its distribution in the state. Source

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