The Effects of Temperature on the Development, Morphology, and Fecundity of Aenasius bambawalei (=Aenasius arizonensis)

The effects of high temperature on the developmental, morphological, and fecundity characteristics of insects, including biological invaders and their accompanying natural enemies, are clear. Phenacoccus solenopsis (Homoptera: Pseudococcidae) is an aggressive invasive insect pest worldwide. Aenasius bambawalei (=Aenasius arizonensis Girault) (Hymenoptera: Encyrtidae) is a predominant accompanying parasitoid of this mealybug. Our previous studies showed that temperature change induced an increase in the female offspring ratio of A. bambawalei. However, whether this increase is the result of a shortened or enhanced development period of the reproductive systems of A. bambawalei remains unknown. Here, we compared the pupal development, hind tibia of female adults, and fecundity of A. bambawalei under different temperatures to clarify the development and morphological changes induced by high temperature and to better understand its potential as an accompanying natural enemy. Our results showed that, at a high temperature (36 °C), the pupal developmental duration of A. bambawalei was only 0.80 times that of the control, and the length of the hind tibia was 1.16 times that of the control. Moreover, high temperature accelerated the developmental rate of gonads and increased the numbers of eggs and sperm. These results indicated that experimental warming shortened the pupal developmental duration, altered the hind tibia length of female adults, and facilitated the fecundity of A. bambawalei. These findings will help to understand the adaptation mechanisms of accompanying natural enemies. Furthermore, these findings will help to make use of this behavior to effectively control invasive pests.

The Cotton Mealybug Is Spreading along the Mediterranean: First Pest Detection in Italian Tomatoes

The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is an extremely polyphagous invasive pest that can cause serious damages to cultivated plants. The pest is native to America but invaded Asian and Mediterranean countries during the last decades. Tomato (Lycopersicon esculentum Mill., Solanaceae) is an economic relevant crop worldwide and its production can be threatened by numerous insect pests including P. solenopsis. We recorded for the first time P. solenopsis in association with tomato in greenhouse crops and urban landscapes in Sicily (Italy) during the fall season in 2020. The species was identified as P. solenopsis based on the morphological characters and DNA amplification of an ≈800 bp portion of mitochondrial cytochrome oxidase subunit I (mtCOI) gene. The phylogenetic analysis among the obtained P. solenopsis mtCOI sequences with those already available in GenBank suggests Asian countries as a potential source of new introduction. This is the first record of P. solenopsis attacking tomato plants in Italy and may represent a potential threat for tomato production in Europe and nearby countries. For this reason, actions should be taken to avoid the uncontrolled spread of this alien species.