Haplaxius crudus

Ramos Hernández, Eder, Magaña Alejandro, Miguel Alberto, Ortiz García, Carlos Fredy, Oropeza Salín, Carlos, Lesher Gordillo, Julia María & Sánchez Soto, Saúl, 2018, The coconut pathosystem: weed hosts of nymphs of the American palm Cixiid Haplaxius crudus (Hemiptera: Fulgoroidea), Journal of Natural History 52 (5 - 6), pp. 255-268 : 263-264

Presence of H. crudus nymphs in weeds

Of the 11 weed species reviewed in this study, eight were used as microhabitats for Cixiidae in at least one period of the year. Brachiaria mutica , E. petraea , B. humidicola and P. maximum are identified in this study as the principle nymphal host species, already have been reported as hosts for H. crudus in different regions of Florida, USA, Colombia, and the Yucatan peninsula of Mexico. This study confirms their role as hosts ( Tables 1 and 2). Additionally, the presence of nymphs on the roots of P. laxum was confirmed (J. Jean- Francois, personal communication, 2007). Brachiaria decumbens , D. abyssinica and C. ligularis are newly reported as weed hosts of nymphs of H. crudus . In this study, these eight species of weeds were a reproductive microhabitat for nymphal development. Populations of these weeds also can provide corridors for vector dispersion in plantations ( Wheeler and Wilson 2014). Additionally, the broad range of vector host plants can increase the population of vector insects, and thus the potential for transmission ( Imo et al. 2013).

The population levels of H. crudus were variable depending on the grass species examined. According to Howard (2001), these differences can result from oviposition preferences, survival rate, or a combination of the two. Additionally, he noted that the host plant preference of H. crudus may also be influenced by environmental conditions such as soil moisture ( Kessler et al. 2011). Soil moisture and other soil characteristics could have affected the abundance of H. crudus nymphs. A good root system structure of host grasses favours survival. It is essential to note that weeds with the greatest quantity of H. crudus nymphs were found in sandy soil with 20 – 30% humidity in the rhizosphere; therefore, it is necessary to assess the role of the condition of the soil as an important factor in nymphal presence and survival. Sforza et al. (1999) reported that in the laboratory rearing of Hyalesthes obsoletus Signoret (Cixiidae) , soil moisture conditions must be 80%. Additionally, Vadell and Hoch (2009) show that it is not unusual for cixiid adults to search for dark, humid spaces for protection against hot and dry environmental conditions. They place their eggs at the base of the stems of their host plants. Paspalum notatum was not a good host in our study, despite being reported as one of the principle host species of H. crudus nymphs in Florida ( Tsai and Kirsch 1978; Reinert 1980). We attribute this to the soil conditions where the plant was growing. In the area where this study was conducted, the presence of P. notatum is limited to the high subzone, so the ideal humidity percentages for nymphs are not present. Leersia hexandra , despite being abundant and associated with B. mutica and P. laxum , was not found to have cixiid nymphs. It is suggested that this was possibly caused by a poor root system and distribution in areas with humidity greater than 40%. Also, this grass has been reported as an allopathic species to insect nymphs ( Heinrichs and Medrano 1984).