The impact of the insecticide cypermethrin on the functional response, predatory behaviour and mating behaviour was studied in a non-target potential reduviid biological control agent Acanthaspis pedestris (Sta˚l). The intensity of abnormal behaviour increased as the concentration of cypermethrin was increased. The insecticide negatively affected the functional response events such as attack ratio, handling time and rate of discovery. Cypermethrin also reduced the predatory efficiency and prolonged the mating events in A. pedestris. The type II (decelerating curve) of functional response was altered into a type IV (dome-shaped curve) by cypermethrin.

A checklist of 464 Indian species of assassin bugs under 144 genera and 14 subfamilies with their taxonomical status, their distribution in India and world over and their morphological characteristics are given. Members of the Harpactorinae are the most abundant group with 146 species and 41 genera followed by the Reduviinae and the Ectrichodiinae. The subfamilies such as the Physoderinae and the Ectinoderinae are represented each by two and lone species. Other characteristics of the family Reduviidae discussed in this overview include the rostrum structure, tibial pads, habitat characteristics, microhabitats and habits. Morphological characteristics are correlated with ecological, behavioural and biological manifestations of the reduviids.

No abstract

The haemogram of Rhynocoris kumarii Ambrose and Livingstone comprises prohaemocytes, plasmatocytes, granular haemocytes, cystocytes and oenocytoids. The impact of five insecticides, viz. monocrotophos, dimethoate, methylparathion, quinalphos and endosulfan on the total haemocyte count (THC) and differential haemocyte counts (DHC) was studied. All of the insecticides except endosulfan initially reduced both prohaemocytes and plasmatocytes, increased the granular haemocytes, altered the percentage of cystocytes and oenocytoids and increased the total haemocyte count (THC). On the contrary, endosulfan initially increased the prohaemocytes and plasmatocytes, decreased the granular haemocytes and also the THC. The highest impact on the DHC and THC was caused by methylparathion and monocrotophos and the least impact by endosulfan. Hence, endosulfan is considered as the safest insecticide followed by dimethoate and quinalphos among these five insecticides to use with R. kumarii.

Mechanism underlying the searching behaviour of the predator Rhynocoris marginatus in different levels of hunger and at different densities of its prey Spodoptera litura was studied within an experimental arena. Starved for 1-day R. marginatus travelled 2.34 times longer distances than starved for 4-day ones to find prey in the four prey density arenas. Total distance travelled by R. marginatus at four S. litura density arenas was 0.4 times shorter than that in one density regime. Searching speed of 4-day hungry R. marginatus was 2.44 times greater than 1-day hungry R. marginatus. R. marginatus at four S. litura density regimes searched at 2.43 times higher speeds than R. marginatus at one density regime. Higher rates of turning were observed in 4-day hungry R. marginatus than in 1-day hungry R. marginatus. Higher rates of turning of R. marginatus were recorded in one S. litura density regime than in four density regimes. One-day hungry R. marginatus turned 4.14-fold greater degree mean angle than 4-day hungry ones. At four S. litura density regime R. marginatus turned 0.34-fold lesser angle than at one density regime.