Problems with the Concept of “Pest” among the Diversity of Pestiferous Thrips

Almost all of the thrips species that are considered pests are members of a single subfamily of Thripidae, the Thripinae, a group that represents less than 30% of the species in the insect Order Thysanoptera. Three of the five major Families of Thysanoptera (Aeolothripidae, Heterothripidae, Melanthripidae) are not known to include any pest species. The Phlaeothripidae that includes more than 50% of the 6300 thrips species listed includes very few that are considered to be pests. Within the Thripidae, the members of the three smaller subfamilies, Panchaetothripinae, Dendrothripinae and Sericothripinae, include remarkably few species that result in serious crop losses. It is only in the subfamily Thripinae, and particularly among species of the Frankliniella genus-group and the Thrips genus-group that the major thrips species are found, including all but one of the vectors of Orthotospovirus infections. It is argued that the concept of pest is a socio-economic problem, with the pest status of any particular species being dependent on geographical area, cultivation practices, and market expectations as much as the intrinsic biology of any thrips species.

Impact of environmental factors on infestation of cashew leaves by leaf miner, Acrocercops syngramma Meyrick in Gujarat

Studies were conducted in a cashew plantation at Waghai, Gujarat, India during 2017 – 19 on cashew variety vengurla- 4 throughout two consecutive years to determine the pest status of leaf miner, Acrocercops syngramma Meyrick and their relation with environmental factor. Damage to cashew leaf by leaf miner was prevailed only from July to December with maximum damage (2.19%) in the month of November 45th SMW in hilly area of the Dangs. Further, pest infestation on leaves found to have significant positive correlation with maximum temperature, mean temperature, bright sunshine and evaporation, while negative with morning relative humidity, evening relative humidity, mean relative humidity and wind speed.

A Generalist Feeding on Brassicaceae: It Does Not Get Any Better with Selection

Brassicaceae (Cruciferae) are ostensibly defended in part against generalist insect herbivores by toxic isothiocyanates formed when protoxic glucosinolates are hydrolysed. Based on an analysis of published host records, feeding on Brassicas is widespread by both specialist and generalists in the Lepidoptera. The polyphagous noctuid moth Helicoverpa armigera is recorded as a pest on some Brassicas and we attempted to improve performance by artificial selection to, in part, determine if this contributes to pest status. Assays on cabbage and kale versus an artificial diet showed no difference in larval growth rate, development times and pupal weights between the parental and the selected strain after 2, 21 and 29 rounds of selection, nor in behaviour assays after 50 generations. There were large differences between the two Brassicas: performance was better on kale than cabbage, although both were comparable to records for other crop hosts, on which the species is a major pest. We discuss what determines “pest” status.

West Indian Drywood Termite Cryptotermes brevis (Walker) (Insecta: Isoptera: Kalotermitidae)

Contents: Introduction - Distribution - Description and Identification - Life History - Damage - Pest Status - Management - Selected References. This article is also published on the UF/IFAS Featured Creatures website at http://entnemdept.ufl.edu/creatures/urban/termites/heterotermes.htm.

Pelopidas mathias (rice skipper).

Due to its wide host range and low reproductive potential, colonization rates of P. mathias are rather low compared to more specialized rice pests. Those ovipositing adults that do arrive do so after significant numbers of natural enemies have built up; this helps to explain the normally low pest status of P. mathias.

Erionota thrax (banana skipper).

The pest status of E. thrax was described early in the 20th Century (Dammerman, 1919, 1929). According to Corbet and Pendlebury (1992) the very similar Erionota torus has the same life history, and some of the records in the literature may relate to this species. For example, Zhang (1994) mentioned Hong Kong and the Chinese province of Guangdong, where only E. torus is known (Hill et al., 1978; Johnston and Johnston, 1980).