Differential flight capacity of Spissistilus festinus (Hemiptera: Membracidae) males and females

Spissistilus festinus (Hemiptera: Membracidae), the three-cornered alfalfa hopper (TCAH), is a pest of legumes and poses a risk to the grapevine industry as a vector of grapevine red blotch virus (GRBV), the causal agent of red blotch disease. Understanding what drives TCAH dispersal capacity is crucial to assess the risk of GRBV spread. Here, we evaluated the flight propensity and flight capacity of male and female TCAH by using a flight mill apparatus under laboratory conditions. Since TCAH shows strong sexual dimorphism, we also assessed the effect of insect morphology on flight performance. We found that TCAH flight propensity and flight capacity is dependent on sex with male insects more likely to engage in flight than females. Flight capacity increased as insects aged with two-to-seven-day old insects flying less time and shorter distances than mature insects (≥eight days), with male insects flying significantly longer than females.. Female TCAH were found to be heavier and to have bigger wings than males; however, these morphological characteristics did not statistically alter flight efficiency. Our findings on maximum flight capacity and intrapopulation flight dynamics are valuable for assessing the risk of GRBV spread in the vineyard.