The bagrada bug, Bagrada hilaris, is an invasive insect pest in the family Brassicaceae that causes economically important damage to crops. It was originally present in Asia, the Middle East, and Africa, and was reported as invasive in the southwestern part of the US, in Chile, and on a few islands in the Mediterranean Basin. In its native range, B. hilaris is controlled by several egg parasitoid species that are under consideration as potential biological control agents. This research evaluated the impact of gamma irradiation on life history parameters, e.g., the fecundity, fertility, and longevity of B. hilaris, as a critical step towards assessing the feasibility of using the sterile insect technique against this recent invasive pest. Newly emerged adults of a laboratory colony originally collected from the island of Pantelleria (Italy) were gamma-irradiated. Life history parameters were evaluated at nine different doses, ranging from 16 Gy to 140 Gy. The minimal dose to approach full sterility was 100 Gy. Irradiation up to a maximum of 140 Gy apparently did not negatively impact the longevity of the adults. Even if both genders are sensitive to irradiation, the decline in fecundity for irradiated females could be exploited to release irradiated males safely to apply the SIT in combination with classical biological control. The data presented here allow us to consider, for the first time, the irradiation of bagrada adults as a suitable and feasible technique that could contribute to guaranteeing a safe approach to control this important pest species in agro-ecosystems. More research is warranted on the competitive fitness of irradiated males to better understand mating behavior as well as elucidate the possible mechanisms of sperm selection by polyandric B. hilaris females.

Olfaction plays a dominant role in insect communication. Alarm pheromones, which alert other insects of the same species of impending danger, are a major class of releaser pheromones. The major components of alarm pheromones in red imported fire ants, honeybees and aphids have been identified as 2-ethyl-3,6-dimethylpyrazine (2E-3,6-DP), isopentyl acetate (IPA), and E-β-farnesene (EβF), respectively. In this study, electroantennography (EAG) responses to EDP (a mixture of 2-ethyl-3,6-dimethylpyrazine and 2-ethyl-3,5-dimethylpyrazine), IPA and EβF were investigated in a wide range of insect species. Beside imported fire ants, the EDP (2-ethyl-3,6(5)-dimethylpyrazine) elicited significant EAG response from all other tested insects, including six ant species and one hybrid ant, honeybee, bagrada bug, lady beetle, housefly, small hive beetle, yellow fever mosquito, termite, bedbug, water hyacinth weevil, southern green stink bug and two aphid species. In contrast, IPA elicited significant EAG response only in the honeybee, red imported fire ant, an Aphaenogaster ant, and the water hyacinth weevil. The EβF only elicited EAG responses in two aphids, small hive beetle and housefly. The results clearly indicate that EDP can be detected by widespread insect species that did not coevolve with S. invicta and further suggested alkylpyrazine may activate multiple generally tuned olfactory receptors (ORs) across a wide number of insect species.

In this paper, we describe the morphology of the female Bagrada hilaris (Burmeister) reproductive system and develop a physiological age-grading system related to egg production. The female reproductive system is composed of two meroistic and telotrophic ovaries each containing 5–6 tubular ovarioles. The ovarioles unite into the lateral oviduct which combine to form the common oviduct. The ovarioles are composed of two regions; the distal germarium and the tubular vitellarium which contains maturing follicles. Each follicle is surrounded by a layer of cells; the follicular epithelium. As the follicle passes from the ovariole to the lateral oviducts the follicular epithelial cells slough off and accumulate in the base of the ovarioles and are known as follicular relics. The continuum of ovarian development is divided into two categories: nulliparous (‘nonreproducing’) and parous (‘reproducing’). The nulliparous category is characterized by the absence of follicular relics or eggs in the oviducts as opposed to the parous category where follicular relics and, in many cases, eggs occurred in the oviducts. The nulliparous category is divided further into two stages; N1 and N2 based on ovariole differentiation. The parous category is divided into three stages; P1, P2, and P3, based on the quantity and appearance of follicular relics. Females characterized as P3 produced three times more eggs (79.2 eggs ± 5.7) than females characterized as P1 (27.1 eggs ± 6.0).

Solenopsis invicta Buren is an invasive ant species that has been introduced to multiple continents. One such area, the southern United States, has a history of multiple control projects using chemical pesticides over varying ranges, often resulting in non-target effects across trophic levels. With the advent of next generation sequencing and RNAi technology, novel investigations and new control methods are possible. A robust genome-guided transcriptome assembly was used to investigate gene expression differences between S. invicta larvae and pupae. These life stages differ in many physiological processes; of special importance is the vital role of S. invicta larvae as the colonies’ “communal gut”. Differentially expressed transcripts were identified related to many important physiological processes, including digestion, development, cell regulation and hormone signaling. This dataset provides essential developmental knowledge that reveals the dramatic changes in gene expression associated with social insect life stage roles, and can be leveraged using RNAi to develop effective control methods.

The southern green stink bug (SGSB), Nezara viridula (L.), is an important agricultural pest in the United States. Limited information is available on the morphology of the female’s reproductive system in relation to morphological changes associated with the number of eggs produced and egg masses oviposited. The ability to assess reproductive health and reproductive status based on ovarian morphology (i.e., physiological age-grading) can be an important tool for evaluating field populations and laboratory colonies intended for the application of different management strategies and experimental trials. Thus, the goal of this study was to develop a physiological age-grading system for SGSB. Females aged from 0 to 79 d chronologically randomly selected from laboratory colonies and dissected to assess ovarian morphology. Specific morphological differences in ovarian structures including differentiation of the ovarioles, deposition of yolk in the most proximal follicle, quantity and appearance of follicular relics, expansion of the lateral oviducts, and number of developing follicles per ovariole were related to chronological age, the number of eggs produced and number of egg masses. Based on specific combinations of these morphological characteristics, the continuum of ovarian development was divided into three nulliparous (i.e., ‘no eggs’; N1, N2, and N3) and three parous stages (i.e., ‘with eggs’; P1, P2, and P3). Direct relationships were noted between number of eggs produced and physiological age with over 7-fold higher number of eggs and 14-fold higher number of egg masses associated with the P2 and P3 stages, respectively.

The morphology of the female Cyrtobagous salviniae Calder and Sands reproductive system is similar to other weevil species being meroistic and telotrophic. The reproductive system is composed of 2 ovaries each containing 2 ovarioles where the follicles mature. A physiological age grading system was developed where the continuum of ovarium development was divided into 2 nulliparous and 3 parous classes. This was based on the differentiation of the ovarioles, presence, and appearance of follicular relics, cuticle hardness/coloration, and fat body quantity/appearance. High correlation occurred between the parous classes and number of eggs produced where the P3 class had over 9-fold higher number of eggs in comparison with the P1 class. Mean number of eggs produced for each parous class was significantly different, however, overlap occurred. Such a system enables a determination of the past, present, and future reproductive status of field populations and mass-rearing colonies.